Messier-Bugatti-Dowty
Airbus Single Aisle Family Landing Gear
IN-SERVICE EXPERIENCE
Issue 4
A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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of Messier-Bugatti-Dowty.
Foreword
This “In-Service Experience” is Messier-Bugatti-Dowty proprietary
Its use is strictly limited to Messier-Bugatti-Dowty customers
It shall never be copied nor transmitted to any other organisation without
Messier-Bugatti-Dowty authorisation
The information given in the “In-Service Experience” is not contractual
In no case may it supersede the applicable Messier-Bugatti-Dowty
Technical Publication (e.g. Component Maintenance Manual, Service
Bulletin, Service Letter, Product Deviation Authorisation etc..) for
operation and/or maintenance purpose.
The inclusion of a topic within the ISE does not mean that it is can be
considered to occur on a fleetwide or repetitive basis unless specifically
mentioned within the slide. In no circumstance can the ISE content be
used against MBD in any claim
1 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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Airbus Single Aisle Family Landing Gear
CONTENTS
/01/ Solutions In Development
1. Nose Landing Gear
2. Main Landing Gear
/03/ Best Maintenance Practices
1. Lubrication of the Landing Gears
2. Cleaning
3. General Checks
/02/ Recommended Solutions
1. Nose Landing Gear
2. Main Landing Gear
/04/ Landing Gear Product Information
1. A320/321 Serialisation SBs
2. Restoration Information
3. Tracking the safe life of parts
4. New Products
5.EV Tooling Information
Note 1 : Revised or New Slides are identified with
• Note 2 : On wing repair documentation previously known as RDAS is now known as RDDAS
2 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1- Nose Landing Gear
1.5 – Barrel Top Face
1.4 - Harnesses
1.3 – Barrel Bush Migration
1.1 - Electrical Box
1.2 - Shock Absorber
1.6 – Proximity Sensor
3 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1.1 - NLG Electrical Box
CONTENTS
Electrical Box
P/N affected: D23119750-1, D23119751119
4 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1.1 - NLG Electrical Box
Description/ Context
•
Several cases of unscheduled removal were reported by various
airlines;
In addition, few cases of NLG electrical box re-connection during
operation have been reported
A MISP was opened in 2011 on these issues
•
•
Consequence
• Several cases of overpressure in the steering system potentially due to
hydraulic system reactivation or non-deactivation during towing phase.
Root Cause Investigation
•
•
•
•
•
•
•
Reconnection issue
Analysis of MBD MRO and supplier repair feedback and in-service
screening to identify candidate and then a root cause;
13 electrical boxes investigated (coming from warranty and in-service)
=> Electrical box not determined as the cause of the in-service issue
Reliability
Reliability analysis performed showing good behaviour of electrical box
in-service for several years
Analysis of MBD MRO and supplier repair feedback to determine
potential reliability improvements
Lamp identified as the main contributor to unscheduled removal
Solution/Mitigation
• Introduction of AMM task in order to allow replacement
of lamp bulb on-wing avoiding unscheduled removal of
the electrical box
• Reliability improvement with introduction of LED
instead of incandescent light
Status Update
• AMM task now available
• LED introduction on-going (will be covered by
dedicated MBD SB 580-32-3177)
=> aim is to perform modification on-wing
• MISP has been considered closed
No link determined between electrical box and reconnection issue.
Reliability improvement with introduction of LED
5 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1.2 - NLG Shock Absorber
CONTENTS
Shock Absorber Leakage - Dynamic Seal
Dynamic Seal P/N affected: S34852-343P99
Sliding Tube Chrome Flaking
Sliding Tube P/N affected: D66679
6 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1.2 - NLG Shock Absorber Leakage - Dynamic Seal
Description/ Context
Root Cause Investigation
Dynamic seal leakages have been reported across the fleet.
In service investigation showed premature wear of the dynamic
seals.
• The average number of cycles performed by seals before
leakage occurs is approximately 6500 cycles
• 46% of seals never cause leakage
Consequence
Grounding of aircraft for removal of shock absorber to replace dynamic
seal.
Solution/Mitigation
•
Specific AMM task for dynamic seal replacement with leg at 45
degrees
•
MBD recommends pro-active replacement as per SL 580-32-3150
SCRAPER
Status Update
•
•
•
•
•
Redesign of the dynamic seal taking into account experience of
various dynamic seals used in MBD shock absorbers
Test results have shown increased reliability with the new seal
MBD and Airbus launched an in service evaluation (ISE) of the new
dynamic seal in order to validate the seal behaviour during aircraft
operation: 1 MBD SB will be issued for installation of the new
dynamic seal
16 aircrafts participate to this ISE without any leakage reported so
far (with around 17404 FC accumulated)
MBD/Airbus are looking for airline candidates for In service
evaluation trial. Contact MBD/Airbus for participation in trial.
New dynamic seal
In service evaluation trial of the new dynamic seal in progress. Future actions will be determined
based on the ISE results.
7 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
h - NLG Sliding Tube Chrome Flaking
1.2
Description/ Context
Root Cause Investigation
Operators reported chrome flaking on the sliding tube. MBD identified a
specific batch.
Note: Not all chrome detachments are linked to this batch issue.
Investigation determined that during the manufacturing process,
cleaning and sand blasting at one source of supply was not
consistently applied, leading to variability of chrome adhesion.
• Population of 200 sliding tubes identified across 60 operators
Consequence
Grounding of aircraft for temporary repair until sliding tube replacement
Solution/Mitigation
• MBD has issued RDDAS temporary repairs for this type of damage.
• Contact AOG CSC (aogcsc@safranmbd.com) if this damage
occurs.
• RDDAS issued by MBD can allow continued A/C operation – around
45 days/200FC
• Dedicated support provided and communicated to all 60 operators
• MBD MRO network used to support the regions with rotable sliders
Status Update
Retrofit ongoing and support available
Warranty extended up to 1st overhaul for sliders concerned by Quality
batch.
Retrofit progressing and dedicated RDDAS support available on request.
8 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1.3 - NLG Barrel
CONTENTS
Barrel Bush Migration
Barrel P/N affected: All
9 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1.3 - NLG Barrel Bush Migration
Description/ Context
Root Cause Investigation
Around 60 cases of migration were reported on
barrel at the actuating cylinder/barrel interface
The migration occurs during the operation
of actuating cylinder
The combination of :
• Significant offset of actuating cylinder
kinematic
• Stiffness of the lug bush flange
Consequence
• Cracked sealant noticed
• Burden in maintenance (bush replacement /
TA request)
Then, axle bending leads to bush migration
in this particular configuration
Mitigation
• MBD issued a Service Letter 580-32-3185 to mitigate the phenomenon in-service. The
mitigation consist to remove the sealant, inspect and clean the area and renew the sealant.
Solution
Some technical proposals are under discussion between MBD & Airbus engineering to
determine if design should be improved
Status Update
MBD Service Letter 580-32-3185 issued in December 2014 to mitigate the phenomenon inservice
Embodiment of MBD Service Letter 580-32-3185 will permit to mitigate this phenomenon and avoid any
bush replacement
10 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1.4 – NLG Harnesses
CONTENTS
Harness Connector Corrosion
A/C affected:
A318/ A319/A320/A321
11 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
All P/Ns
/01/ Solutions In Development
1.4 – Harness Connector Corrosion
Description/ Context
Some operators have reported corrosion of NLG /
MLG electrical connectors to MBD and Airbus.
Consequence
Corrosion may result in connector replacement in
service or at overhaul.
Status Update
The connectors comply to Airbus Supplier
Equipment Specification
MBD are supporting Airbus in the solution
development
Refer to Airbus TFU 32.00.00.007 R14
12 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
1.5 – NLG Barrel Top Face
CONTENTS
Barrel Top Face Corrosion
13 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ In Service Experience
1.5 - NLG Barrel top face corrosion
Description/ Context
Root cause investigation
Several cases of corrosion have been reported on the top
face of barrel and on barrel bolt holes in service and in
shop
Based on feedback from in-service and in shop, the main contributor is
degradation of the sealant around the barrel bolts.
After degradation of the sealant, moisture is able to go through the barrel
bolts leading then to protective treatment degradation and corrosion
development.
This sealant degradation could be due to several contributors:
• Improper sealant application during potential previous maintenance tasks
• Protective treatment degradation between Barrel and Upper support
Consequence
The corrosion has to be removed by re-machining the top
face or the holes leading to higher overhaul costs
(additional repair or part replacement).
Recommendation
• Airbus ISI 32.31.00004 has been developed with MBD to
provide information about inspection of sensitive areas.
• Regular visual inspection on this area could allow to
detect any damage on rubber sealant and prevent any
corrosion development
Mitigation
• Segregation in the RC analysis between CIS and nonCIS operation is under study with Airbus.
• Target for this new disposition is Q3 2016
• Life limitation at 1 TBO is under investigation on non-CIS
aircraft
Segregation of life limitations via RC under study to reduce Pre EV Barrel scrap
14 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ In Service Experience
1.6 - NLG Proximity Sensor System
CONTENTS
NLG Proximity Sensor
Proximity sensor mechanism P/N affected:
Post SB 580-32-3155 / 3157
15 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ In Service Experience
1.6 - NLG Proximity Sensor System
Description/ Context
Root cause investigation
Some airlines reported abnormal play on NLG Proximity sensor
mechanism (post-SB 580-32-3155 / 3157) either during maintenance
check or after troubleshooting (in case of 24/25Ga fault triggered).
Some proximity sensor mechanism have been recovered from
maintenance check for laboratory analysis:
• Wear is mainly noticed at level of bushed lever and greased
pin
Consequence
• High rate of parts replacement during maintenance check
• Potential risk of Operational Interruption linked to proximity sensor
mechanism issue
Analysis is still on going to correlate in-service data with
mechanism free play leading to loss of signal.
Sample analysis is on-going via MRO to assess level of wear
at Overhaul.
Mitigation
• Replacement of worn or damaged parts
• Preventive maintenance according to Airbus AMM
Task 32-21-00-210-802-A
Status Update
Engineering analysis on-going.
MRO sampling on-going.
Investigation report to be shared between MBD and Airbus in Q1 2016
Report conclusion will drive decision on the way forward
Feedback from Customer is needed in case of event related to 24/25GA
Investigations on going. MBD to gather additional data from operators
16 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
2 - Main Landing Gear
2.6 Pintle Pins
2.5 - Lockstay Actuator
2.4 - Sliding Tube
2.3 - Quick Release Coupling
17 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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2.1 - Harnesses
2.2 - Torque Link Damper
/01/ Solutions In Development
2.1 - Harnesses
CONTENTS
Harness Connector Corrosion
A/C affected:
A318/ A319/A320/A321
18 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
All P/Ns
/01/ Solutions In Development
2.2 – Harness Connector Corrosion
Description/ Context
Some operators have reported corrosion of NLG /
MLG electrical connectors to MBD and Airbus.
Consequence
Corrosion may result in connector replacement in
service or at overhaul.
Status Update
The connectors comply to Airbus Supplier
Equipment Specification
MBD are supporting Airbus in the solution
development
Refer to Airbus TFU 32.00.00.007 R14
19 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
2.2 - Torque Link Damper
CONTENTS
MLG Torque Link Damper Loose Bolts
A/C affected:
A319/A320/A321
20 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
201404001
/01/ Solutions In Development
2.2 - Torque Link Damper Loose Bolts
Description/ Context
There have been reports of the bolts that attach the torque link
damper becoming loose. These bolts attach the torque link
damper to the upper torque link. The torque link damper is also
attached by the torque link apex pin.
5mm additional material
added to the face.
Consequence
Corrosion to the bolts and the bolts becoming loose, although the
torque link damper cannot become detached as it is also attached
by the torque link apex pin.
Root Cause Investigation
Thread tapping was in some cases not to the full depth required.
The thread inserts when installed in these holes became tapered.
When the bolts for the torque link damper were installed in the
tapered insert the bolts would not torque correctly.
Solution
A revised damper with increased depth of the tapped holes had
been produced for the EV MLG, the revised damper will also be
available as a modification to the Enhanced MLG.
The modification to apply the revised torque link damper is under
final approval, VSB expected Q3 2016.
The modification to apply the revised torque link damper is under approval.
21 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
2.3 - Quick Release Coupling
CONTENTS
MLG Quick Release Coupling Hydraulic Leaks
A/C affected:
A318/ A319/A320
22 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
201042031
/01/ Solutions In Development
2.3 - Quick Release Coupling Hydraulic Leaks
Description/ Context
MBD have received a number of reports of hydraulic fluid
leakage from above the union nut on the brake flexible
hydraulic hose elbow at the junction of the Quick Release
Coupling.
Consequence
Hydraulic fluid spilling on hot brakes may cause brake smoke
or brake fire during taxi-in or parking phases.
Root Cause Investigation
• On parts returned to MBD, galling damage was observed on
the non threaded parts of the mating faces of the QRC and
flexible hose which can be caused by vibration.
• Some cases coincide with piston housing loose on MBD
brakes Ref: VSB C20225-32-3391, SL F6137-32-3389 and
Airbus TFU 32.42.27.037 due to non-compliant locking bolt
assemblies
Mitigation
Airbus Alert Operators Transmission -A32N005-14 dated 11
Sep 2014 calls for a one-time visual inspection of the QRC and
the MLG brake piston housing bolts on A318, A319 and A320
aircraft equipped with MBD MLG Brake assemblies PN
C20225508, C20225509 and C20225510.
Status Update
MBD is continuing to monitor occurrences in service.
MISP closed.
23 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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Galling damage
/01/ Solutions In Development
2.4 - MLG Sliding Tube
CONTENTS
MLG Sliding Tube Thermal Damage and Cracking
A/C affected:
A318/A319/A320/A321
P/N affected:
All P/Ns
Axle Overheating Damage
A/C affected:
A321
P/N affected:
All P/Ns
Slave Link Lug Crack
A/C affected:
A318/A319/A320/A321
24 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
201271304, 201522353
/01/ Solutions In Development
2.4 - MLG Sliding Tube Thermal Damage And Cracking
Root Cause Investigation
Description/ Context
• Operators have reported local chromium plate detachment
and base material cracks on the main barrel diameter.
• A/C Flying into CIS Regions have been particularly affected
and a low numbers of operators outside of the CIS region
have also been affected.
Consequence
• Increased risk of unserviceable Sliding Tubes at next shop
visit.
• Cracking to the sliding tube.
• Increased risk of Shock Absorber fluid leakage.
Investigation has shown increased Shock Absorber velocity and Bearing
friction between the Sliding Tube and Lower Bearing can lead to this
damage.
Damage typically occurs in the working region of the Lower Bearing
during the taxi phase of operation.
Runways and taxiways with increased surface roughness can increase
the probability and severity of damage.
Base metal thermal damage on
rear of slider
Mitigation
• MBD has provided RDDAS temporary repairs for this type of
damage. Contact AOG CSC (aogcsc@safranmbd.com) if this
damage occurs.
• Repetitive inspections for CIS operators including DVI and MPI
inspections.
• Operators may choose to reduce greasing intervals in this
area. Particularly if flying into CIS region where it is
recommended to grease weekly.
Solution
Chromium plate detachment on
rear of slider
Solution
Mitigation actions and a solution are available.
25 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
2.4 - MLG Sliding Tube Thermal Damage And Cracking
Solution
MBD SB 200-32-307, 201-32-58, 200-32310, and 201-32-60. The new standard of
bearing includes:
• A new low friction inner liner and shorter
retaining pins
• The inner liner consists of a lead
impregnated PTFE layer mounted on a
bronze backing
• Existing Lower Bearing assemblies can be
modified at overhaul
• The embodiment of the new Lower
Bearing is currently controlled by Airbus,
affected operators out of the CIS region
can request the solution from Airbus.
New lower
bearing
subassembly
201587212
Status Update
• Endurance limits to be published by Airbus
into Airbus SB A320-23-1386.
•
•
The life of the bearing in the CIS region will be
5800 FC.
Further analysis of bearings is not expected to
allow any improvements on this.
Inner liner
201646300
Area of
wear
Post Mod
Lower
Bearing
Acceptable
In-service
condition
• Liners are being returned by some operators
outside of the CIS region for wear analysis.
Back to Description
Solution available to remove need for repetitive inspections and prevent in-service damage
26 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
2.4 - MLG Axle Overheating Damage
Description/ Context
Mitigation
MBD has received reports of local
chromium plating detachment and base
metal overheating on the innermost
chromium plated Axle diameter (next to the
Brake Flange). Damage is found to be
more common on A321 Aircraft.
• On all A321 aircraft, a regular greasing of the
MLG Axle outer diameter and Axle Sleeve
inner diameter is recommended to be
performed every 2000 FC. Refer to TFU
32.11.00.005 and Airbus SIL 32-130.
Consequence
Risk of Sliding Tube being deemed
unserviceable.
Root Cause Investigation
Most likely cause of overheating is fretting
between the Axle Sleeve and innermost
chromium plated Axle land.
Subsequent heat generation can, in some
cases, be sufficient to change the
microstructure and properties of the base
metal.
• MBD has issued RDDAS temporary repairs
for this type of damage which requires at
minimum acid etch to PCS 3600. Contact
AOG CSC (aogcsc@safranmbd.com) if this
damage occurs.
• Repair off-wing is covered by applicable CMM
repairs. For damage exceeding this a repair
solution has been developed but is subject to
approval by a Repair Concession.
Status Update
• All MBD information on root cause effects has
been passed to Airbus to assist with solution
development at interface level.
MBD recommend regular greasing of Axle – refer to Airbus SIL and TFU.
27 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
MLG Sliding Tube Slave Link Lug Crack
2.4 - MLG Sliding Tube Slave Link Lug Crack
Description/Context
Root Cause Investigation
At overhaul 2 sliding tubes from different operators were found to
have a crack in the Sliding Tube slave link lug area when NDT tested
at overhaul
The fracture propagated from a burr in 1 of the 4 slave link lug
holes. The fracture did not extend into the barrel of the sliding tube
Possible Consequence
• Suspect population identified, MBD VSB to be updated with the
population expected Q2 2016.
• Scrapping of Sliding Tube if crack found
• Crack in Principle Structural Element therefore airworthiness
directive expected
Slave Link Lug location (aft)
Mitigation / Solution
• MBD VSB released to check for burrs at overhaul, Airbus SB and
Airworthiness Directive Expected to Mandate Inspection at overhaul
or on-wing.
• De-burring operation at manufacture has been improved.
Inspection and Mitigation in development for Enh sliding tubes in service
28 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
2.5 - Lockstay Actuator
CONTENTS
Lockstay Actuator Leakages
A/C affected:
A318/A319/A320/A321
29 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
114095 series
/01/ Solutions In Development
2.5- Lockstay Actuator Leakages
Description/ Context
Mitigation
A number of warranty claims have been received by
MBD for Lock-stay Actuator Leakages. Typical
findings on actuators are; cracked / pockmarked seal
elastomer and worn / torn atmospheric side back-up
ring.
MBD recommends frequent completion of the below (as often as weekly or even daily) and immediately
after actuator installation.
1. Ensure the MLG is in the down locked position and is safe in accordance with AMM procedures
2. Using a Lint free cloth and a small amount of cleaning fluid; clean the Lockstay Actuator Piston Rod OD
to remove any old Hydraulic Fluid, Dirt, Debris or Contamination. Ensure that no cleaning fluid gets
inside the actuator past the scraper seal assembly.
3. Using a Lint free cloth dry the Lockstay Actuator Piston Rod OD
4. Using a Lint free cloth apply a layer of Hydraulic fluid onto the Lockstay Actuator Piston Rod Chrome
Plated Diameter
Consequence
• Potential for hydraulic fluid leakage and
unscheduled maintenance
• Economic burden to repair leaking units
Root Cause Investigation
Primary Factor
• Use of Skydrol LD-4, Hyjet IV-A+, Skydrol PE-5, and
Hyjet V may result in a gland fill percentage greater
than 100% increasing the risk of back-up ring extrusion
and / or frictional related damage to the seal. Possible
geographic / environmental factors have been
identified, suggesting further investigation of another
actuator is required to confirm the correct root cause.
NOTE: MBD recommends using the same Hydraulic Fluid as used in the Aircraft Hydraulic System to
ensure compatibility.
Status Update
• MBD will investigate another actuator to investigate for any possible regional or environmental effects,
depending on the results a solution for fluid in-compatibility may be implemented.
• Operators are invited to contact MBD regarding repeat cases of lockstay actuator leakages so that
another actuator can be investigated.
Secondary Factors (cannot individually cause a leakage)
1. The Piston Rod Surface Finish is smoother than
recommended. Which reduces the amount of fluid
that can sit in “troughs” on the piston rod OD
increasing seal friction
2. Piston Rod ‘wiping’ (with and without cleaning fluids)
in scenarios where the seal is not allowing sufficient
fluid to pass and form a lubricating layer on the
piston rod increases seal friction
Cracked /
pockmarked
seal
Worn / torn
back-up ring
Root cause identified and mitigating actions available to operators
30 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/01/ Solutions In Development
2.6 - Forward Pintle Pin Retaining Bolts
CONTENTS
Forward Pintle Pin
Retaining Bolts
A/C affected: A318/A319/A320/A321
31 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.6 – Forward Pintle Pin
Description/ Context
MBD has received a report from an operator of multiple occurrences of
Chrome plate detachment and base metal corrosion on A320 and A321
MLG Forward Pintle Pins. Another operator found a Forward Pintle Pin
that was rotated and had fractured lugs.
Consequence
In all cases the damages were discovered during routine inspections
and did not result in any direct impact on the operation of the aircraft.
However if the base metal of the pin is corroded there is an increased
risk of fracture of the Forward Pintle Pin which could lead to collapse of
the MLG.
Solution/Mitigation
MBD recommend the following:
•
Check for signs of corrosion product when performing maintenance or
inspections in the area
•
When greasing at this location, ensure that greasing is performed
effectively and check the condition of the extruded grease for signs of
metallic particles
•
If there is doubt about the condition of the Pintle Pin then consider
investigating further.
Root Cause Investigation
The investigation into the root cause of the damage is on-going however it is
expected that ineffective lubrication in the region may be causing increased
friction between the Forward Pintle Pin and the Aircraft Spherical Bearing.
Regular and effective greasing is effective mitigation.
32 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1- Nose Landing Gear
1.7 - Retraction Actuator
1.1 - Unlock Actuator Inspection
1.4 -Panel and Barrel
Greasing Ducts
1.2 - Shock Absorber Cylinder
Colouration
1.5 - Turning Tube
1.3 - Proximity Sensor System
1.6 NLG ICY Modification
1.8 - Torque Links
NLG Leg P/N affected: All P/N
33 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.1 - NLG Unlock actuator
CONTENTS
Unlock actuator Inspection
P/N affected: D23076000 series
34 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.1 - NLG Unlock Actuator Inspection
Description/ Context
Root Cause Investigation
Cases of spherical ball partial or complete migration.
Root cause a combination of:
Consequence
Risk of incomplete NLG retraction or down-locking.
• Insufficient swaging and/or
• Installation of specific “long” bolts P/N D62597
Solution
• Bolt P/N D62597 must be replaced as per MBD SB 580-32-3169
• SB contains instructions for correct swaging and check improvements
• MBD SB 589-32-3169 available on MBD portal
Embodiment of MBD SB will prevent bearing migration and unlock actuator damage.
35 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.2 - NLG Shock Absorber Cylinder
CONTENTS
Shock Absorber Cylinder Colouration
P/N affected:
D65519
36 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.2 - NLG Shock Absorber Cylinder Colouration
Description/ Context
During scheduled shock absorber removal, a few
cases of marks noticed on the cylinder has been
reported by operators.
Consequence
• Customer requests for technical recommendation
• Potential delay in maintenance schedule
Root Cause Investigation
• Marks are due to friction, bronze deposit or heating
• Brownish marks do not require any further action
• Bluish marks require NDT (FPI + Stress Scan)
Solution
Service Letter 580-32-3172 available on MBD portal.
Brownish mark on sliding tube
MBD SIL provides the procedures necessary for different colour indications
37 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
h
1.3 - NLG Proximity Sensor System
CONTENTS
NLG Proximity Sensor
38 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
h
1.3 - NLG Proximity Sensor System
Description/ Context
Cases of Lever Pin showing wear.
pre-mod
Consequence
• Risk of seizure leading to rod-link bending or rupture
• Potential In Flight Turn Back linked to proximity sensor
issue
Solution/Mitigation
• Pin lubrication ducts introduction;
• Rod link reinforcement (from aluminium to steel)
Status Update
• MBD SB 580-32-3155 available on MBD portal
• MBD SB 580-32-3157 available on MBD portal
post-mod
Embodiment of MBD SB’s will reduce risk of rod-link bending and potential for In Flight Turn Back
39 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.4 - NLG Barrel & Panel
Panel Greasing Ducts and
Barrel Greasing Ducts
A/C affected:
A318/A319/A320/A321
40 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
All
/02/ Recommended Solutions
h
1.4 - NLG Barrel & Panel Greasing Ducts
Description/ Context
• Grease could be accumulated on Barrel and Panel hinge pin leading
to grease overpressure inside the blanking cap cavity
Consequence
• Lack of grease on outside area of pintle pins
• Presence of dried grease inside the greasing duct
Solution/Mitigation
•
•
Modification of grease duct to improve the way out for the grease
• Machining of current greasing ducts
• Replacement by new one
Improvement of pintle pins greasing
Status Update
•
•
MBD SB 580-32-3179 available on MBD portal
Airbus issued a covering SB 32-1417
Embodiment of MBD SB will reduce risk of lack of grease or presence of dried grease
41 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.5 - NLG Turning Tube
CONTENTS
Turning Tube Lug Corrosion
Turning Tube P/N affected: D65520 ; D59418 ;D62385
42 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.5 - NLG Turning Tube Lug Corrosion
Description/ Context
Root Cause Investigation
Corrosion has been found on the inner
diameter of the turning tube lug at the upper
torque link attachment.
The corrosion seen in this area is a result
of moisture ingress between the bush and
the turning tube lug inner diameter
Consequence
Repair required for removal of corrosion.
Solution/Mitigation
• Preventative maintenance practices are outlined in the Airbus SIL 32-144 to mitigate such
corrosion:
• Grease lubrication points frequently between the turning tube and upper torque link- MBD
recommendation is every 200 FC
• Check sealant is continuous around the bushes within the turning tube lugs area
• Check sealant is continuous and well coated in the nut and around the head of the pin
between the barrel and the upper torque link
Turning tube lug
• MBD have included a local repair into relevant CMM’s
• If repair is outside of CMM scope, contact AOG CSC (aogcsc@safranmbd.com ), to apply
for a RDDAS Temporary Repair.
• MBD SIL 580-32-3184 has been issued to inform operator about CIC application to help
prevent corrosion (CMM will be updated accordingly in September 2015)
Status Update
Use of anti-corrosion compound for the affected area is under analysis.
Water/moisture ingress path
SIL 580-32-3184 released and CMMs repair will be updated in September 2015
to introduce corrosion inhibiting compound in area
43 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
h
1.6 - NLG New Configuration Leg (ICY)
Description/ Context
New LRU’s created:
More than 20 versions of NLG legs in service, depending on weight variants. ICY
requested by operators at FAIR Working Group.
Consequence
• Technical adaptation could be needed on AOG basis
• Management of different versions of spares
• Various CMM/AMM documentation to refer in service
Solution/Mitigation
•
A modification kit has been produced to create a common NLG
• 4 to 6 man hours required
• 3 new LRU are created:
•Servicing placard kit
•Green or yellow circuit kits
•TPIS or Non TPIS kits
• Configuration harmonization (Reduction in NLG versions, ICY with old parts
increased, ease in spares management);
• Flexibility for customers (new LRU managed through AMM tasks)
Status Update
• MBD SB 580-32-3173 embodiment subject to a dedicated support – CSC & CSM
to be contacted
• MBD SB 580-32-3173 issued to cover this new configuration
• CMM documentation created/updated to include new P/N standard (post MBD
SB 580-32-3173)
• Airbus issued a covering SB 32-1392 & SIL 32-136
1Dependant on weight variant compliance
Implementation will lead to an ease in configuration management. Post SB spares can be used on any A320
Aircraft1. Customization possible with optional kits. MBD SB is a prerequisite of any further modification.
44 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.7 - NLG Retraction Actuator
CONTENTS
Retraction Actuator Leakage
P/N affected: D23613000
45 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.7 - NLG Retraction Actuator Leakage
Description/ Context
• Cases of premature leakages (recently delivered actuators) have
been noticed in service, and through warranty claims since 2010.
Consequence
• Potential operational impacts able to create AOG situation and/or
flights cancelled – not experienced to date
Root Cause Investigation
•
•
Investigations have been performed on several actuators recovered
from in-service
Static leakage has been highlighted during investigation
•
Quality investigation performed permitting to determine 2
contributors of the static leakage :
1. Squeeze of a specific static seal NAS1611-233 batch below
MBD specification
2. Inner diameter of the actuator cylinder P/N D65540 with a
specific tolerance in the static seal area
•
These 2 contributors taken separately would not cause any leakage
of the actuating cylinder from the static seal area and no specific
preventive or corrective action is required in that case.
Solution/Mitigation
• Components affected are NLG actuating cylinders P/N
D23613000 Serial Numbers from MA0723 up to and
including MA1418
• Replacement of the affected static seal NAS1611-233
is sufficient to prevent similar leakage.
Status Update
• MBD Service Letter 580-32-3183 released in April 2014
to cover technical and commercial aspects
Replacement of the affected seal enough to prevent similar leakage.
MBD SIL released to cover technical and commercial aspects
46 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
1.8 - NLG Torque Links
CONTENTS
Torque Link Apex Pin Rupture
Torque Link Apex Pin P/N affected: D64433
47 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
H
1.8 - NLG Torque Link Apex Pin Rupture
Description/ Context
Root Cause Investigation
Several cases of apex pin rupture have been reported during aircraft
operation.
Investigation has identified :
• External bending loads in Apex pin due to contact with
towbarless tractor doors
• No free-play within locking mechanism (nut over-torquing)
Consequence
Possible NLG overload, and/or damage to NLG Tyres or torque links.
Solution/Mitigation
The following solutions were established:
• New locking system which provides adequate free-play avoiding pin
overloading
• Shorter torque link apex pin to increase clearance to the tractor
Figure showing shorter pin and new locking mechanism
Status Update
MBD SB 580-32-3178 has been approved by Airbus, MBD SB 580-323173 is a prerequisite.
Fracture at thread
Embodiment of MBD SB will significantly reduce the possibility of apex pin rupture.
48 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2 - Main Landing Gear
2.1 - Retraction Actuator
2.10 - Main Fitting
2.2 - Pintle Pins
2.9 - Lockstay Actuator Hoses
2.8 – Side Stay
2.3 - New Charging Labels
2.7 - Sliding Tube
2.4 - Lower Bearing
2.6 - Torque Link Damper Disk Spring
2.5 - Harnesses
49 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.1 - MLG Retraction Actuator
CONTENTS
Hydraulic Ports
P/N affected:
201590 & 114193 series
Cylinder Corrosion
P/N affected: 201590 series
50 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
h
2.1 - MLG Retraction Actuator Hydraulic Ports
Description/ Context
Repetitive inspections of retraction actuators were
introduced by Airbus ISB A320-32-1298 to check the
condition of the hydraulic ports at the open end of retraction
actuators.
Open end of
Retraction Actuator
Diameter
increased
Consequence
• Possibility of hydraulic leakage.
• Repetitive inspections required .
Root Cause Investigation
MBD testing using updated in-service data introduced the
possibility of cracks occurring in the hydraulic ports at the
open end of the retraction actuator.
Piston Rod
Solution/Mitigation
Hydraulic Ports
• A solution is available to modify the affected hydraulic ports and remove repeat inspection
requirements by expanded the diameter of hydraulic ports using a cold working method.
• A new production standard cylinder is available that does not require the repeat inspections.
• Rework of existing units is available (MBD SB 200-32-299 & MBD SB 201-32-51)
• Recommended before 20,000 FC, embodiment after 20,000 FC risks causing damage to
cylinder
Embodiment of MBD SBs will remove the need for inspections and reduce the risk of hydraulic leakage.
51 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.1 - MLG Retraction Actuator Cylinder Corrosion
Description/ Context
Corrosion has been found in the retaining ring groove of enhanced in-service retraction actuator cylinders.
Consequence
There is limited reparability in this location, and likely that corroded cylinders will be considered unserviceable.
Root Cause Investigation
Three factors combine to cause the corrosion.
•
Sealant application can allow voids in sealant to
remain.
•
Moisture from scraper seal will tend to flow into any
voids present in the assembly.
•
Galvanic difference between the base materials in
the assembly causes an electrochemical reaction.
Corrosion
Design mitigates risk
of galvanic corrosion
To reduce risk of moisture
ingress
Thin Chromium Plate added
To add corrosion protection to
base metal
ROD
RETAINING RING
• Material Change
Solution/Mitigation
• EASA AD No.: 2013-0283R1, FAA AD No.: 2014-2305, and Airbus SB A320-32-1408 require replacement
and overhaul of affected actuators within 18 months
(from 13/12/13).
• MBD SB 200-32-318 & 201-32-66 introduce a new
standard of cylinder which is repairable with improved
protective treatments.
• MBD SB 200-32-311 & 201-32-61 modifies the
existing cylinder with improved protective treatments.
Sealant Application Improved
GLAND
Increased
chamfer
• Addition protection of
Cadmium Plate & Primer
Paint
To increase corrosion resistance
To suit chromium
plate
CYLINDER
Sealant Introduced
Production Solution
Increased Cylinder O/D
providing more
reparability
Primer Paint added to
cylinder ID
For corrosion resistance
Embodiment of MBD Service Bulletins will reduce corrosion.
52 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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To reduce risk of moisture
ingress
/02/ Recommended Solutions
2.2 - MLG A320/A321 Forward Pintle Pin Retaining Bolts
CONTENTS
A320/A321 Forward Pintle Pin
Retaining Bolts
A/C affected:
A318/A319/A320/A321
53 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.2 - MLG A320/A321 Forward Pintle Pin Retaining Bolts
Description/ Context
Pre - mod
Cases of cross bolt fracture which retains the pintle pin
Consequence
• Could result in subsequent loss of pintle pin.
Root Cause Investigation
Additional external loads caused fractures of the cross
bolt in the pintle pin.
Solution/Mitigation A320
A321 Post - mod
• MBD Service Bulletin introduces 2 stub bolts to
replace the one cross bolt that secures the pintle pin.
• MBD SB 200-32-261 parts are superseded by
serialised parts from SB 200-32-271.
A320 Post - mod
Solution/Mitigation A321
• MBD Service Bulletin introduces new stub bolts
connected by a bowden cable to replace the one
cross bolt that secures the pintle pin.
• MBD SB 201-32-22 parts are superseded by
serialised parts from MBD SB 201-32-40.
Embodiment of MBD SB 201-32-22 will reduce the risk of loss of the pintle pin
54 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.3 - MLG New Charging Labels
CONTENTS
MLG New Charging Labels
A/C affected:
A318/A319/A320/A321
55 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.3 - MLG New Charging Labels
Description/ Context
Labels that show the weight on wheels inflation pressures
were deemed to be unclear
Consequence
Possible incorrect servicing of the shock absorber
Root Cause Investigation
Based on in-service feedback from operators, the
charging labels were unclear.
Solution
MBD SB 200-32-302 and MBD SB 201-32-53 (A321)
introduces new charging labels with increased clarity.
New charging labels introduced with increased clarity
56 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.4 - MLG Lower Bearing
CONTENTS
Lower Bearing Outer Diameter Corrosion
Lower Bearing P/N affected: Pre SB 200-32-297
Lower Bearing Inner Diameter Corrosion
Lower Bearing P/N affected: 201587213 only
57 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.4 - MLG Lower Bearing OD Corrosion
Description/ Context
Fretting and corrosion has been found on the outer diameter of the lower
bearing during seal change and scheduled maintenance.
Consequence
Potential hydraulic fluid leakage, replacement of lower bearing in extreme
cases and possible damage to main fitting at interface.
Root Cause Investigation
Investigations have determined that the root cause of this corrosion is
fretting of the OD of the lower bearing and liner, this results in degradation
of the anodised coating and exposes the base material.
Mitigation
Possible repairs available on application of MBD RDDAS
Note: In some cases bearings are required to be replaced
Solution
MBD SB 200-32-297 & 201-32-49 issued.
• Introduction of a new lower bearing sub assembly with an extended
liner which reduces the possibility of fretting and corrosion on the OD of
the Lower Bearing.
Improved corrosion resistance noted from post mod lower bearings in
service.
Pre-mod
Post-mod
New lower bearing available. Improvement in corrosion performance evident.
58 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.5 - Corrosion of LB IDs behind DU-B Liners
Description
An operator has reported that during DU-B liner replacements their bronze
lower bearings suffer from corrosion at the interface with the DU-B liner. The
corrosion is de-alloying corrosion which removes the zinc, aluminium and
manganese alloying components from the lower bearing ID and deposits them
on the OD of the DU-B Liner.
Consequence
• On-wing RDDASs can be requested from MBD for temporary repair to
remove the corrosion.
• Or replacement of Lower Bearings Assembly and then subsequent
replacement of bronze bushing at MRO.
Root Cause
The corrosion has been caused by excessive moisture present in the region
as a result of contamination of grease with an aqueous fluid before the grease
is pumped into the lower bearing, or introduction of moisture into the Lower
Bearing region during other Landing Gear maintenance activities (such as
cleaning or de-icing operations).
Solution / Mitigation
This can be avoided by taking care not to contaminate grease before use on
the aircraft. Additional care should be taken during cleaning / de-icing
operations to ensure that there is no moisture ingress past the sliding tube
scraper seal.
59 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.5 - MLG New 1M And 2M Axle Harnesses
CONTENTS
MLG New 1M and 2M Axle Harnesses
A/C affected:
A318/A319/A320/A321
Overhauled 2M Harnesses
A/C affected:
A318/A319/A320/A321
60 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
Enhanced only
/02/ Recommended Solutions
2.5 - MLG New 1M And 2M Axle Harnesses
Description/ Context
There have been cases reported where
the tachometer connectors have been
installed to the wrong sensor.
Consequence
• Incorrect reading of the wheel
revolutions to the BCSU
Root Cause Investigation
• Incorrect installation between the
tachometer connectors and the
sensor
Solution/Mitigation
• MBD SB 200-32-304
(A318/A319/A320) /201-32-56 (A321)
Service Bulletin introduces yellow
sleeves on all the cables to all the
inboard connections for clearer
identification.
Axle
Embodiment of MBD SB will reduce the risk of incorrect installation
61 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ RECOMMENDED SOLUTIONS
2.5 - Overhauled 2M Harnesses
Description/ Context
Some overhauled 2M MLG Leg harnesses have had arcing events
in the area below the center of the torque links.
 FWD
Consequence
There is a cockpit warning that the auto brake system is disabled.
There are no structural consequences.
Root Cause Investigation
Clamp block
Investigation found that the contractor that overhauled the
harnesses had used cables of an incorrect specification and that
the cables were shorter than required. Also the lower conduit
subassembly did not have the drain holes in the correct position.
Area where 2M
Harness has had
damage
Solution
• MBD has identified the affected population
• The contractor for the harness repair has updated their
procedures
• MBD SL A320-A33 has been released to provide guidance on
the desired physical condition of the 2m harness following any
refurbishment , repair, or restoration.
Retrofit actions completed by MBD MRO for affected Airlines and SL released.
62 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.6 - MLG Torque Link Damper Disk Spring
CONTENTS
MLG Torque Link Damper Disk Spring
A/C affected:
A319/A320/A321
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/02/ Recommended Solutions
2.6 - MLG Torque Link Damper Disk Spring
Description/ Context
Some torque link damper springs have fractured
when the torque link damper has been
disassembled for inspection.
Consequence
• Potential internal damage to the damper
• No effect on MLG operation.
Root Cause Investigation
The disk springs were found to have fractured in
a fatigue mode
Solution/Mitigation
MBD SB 200-32-268 (A319/A320) / 201-32-28
(A321) introduces new disk springs which have
increased fatigue life.
Affected Disk Springs
Embodiment of MBD SB will reduce the risk of fracture of the disk springs
64 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.7 - MLG Sliding Tube
CONTENTS
Axle End Cracks
Sliding Tube P/N affected: All P/Ns
Dowel Hole Deformation and cracks
Sliding Tube P/N affected: All P/Ns
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/02/ Recommended Solutions
2.7 - MLG Axle End Cracks
Description/ Context
MBD has received some reports of cracks at the threaded end of
the Sliding Tube Axle. Cracks have been located at the Axle Nut
Locking Bolt holes and also in the plain section between the holes.
Consequence
Risk of Sliding Tube being un-repairable at the next shop visit.
Solution/Mitigation
• MBD recommends care is taken not to impact the ends of the
MLG Axles. Use the Axle Thread Protector mentioned in the
AMM. The following notes are included in the AMM:
Root Cause Investigation
On a number of occasions deformation has been observed on the end
of the Axle in the cracked areas. This indicates an impact has
occurred.
No evidence of crack propagation by fatigue has been observed in
components investigated by MBD.
It is most likely that cracking has formed due to the presence of
residual stress. Residual stress is most likely to have been imparted
through impact at the end of the Axle.
• MBD has provided off wing Repair Concessions for a number of
instances where this damage has been found.
• Contact AOG CSC (aogcsc@safranmbd.com) if this damage
occurs on wing.
Take care to protect Axle ends. Use the Axle Thread Protector specified in the AMM.
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/02/ Recommended Solutions
2.7 Dowel Holes Deformation and Cracks
Description/ Context
Root Cause Investigation
MBD has investigated a case of deformation and cracking around the dowel holes at the top
end of the Sliding Tube. The damage was found by the operator during scheduled
maintenance and did not have any direct operational impact.
The investigation revealed that all 6 dowel holes were
cracked and that there was higher than normal stress scan
readings in the base material of the sliding tube.
The deformation and cracking observed was caused by
higher than normal velocity collisions of the Retaining Collar
with the Upper Diaphragm Tube following extension of the
Sliding Tube during take off. These high velocity collisions
are the result of underdamped extensions of the Sliding
Tube which are caused by an incorrect balance of hydraulic
fluid.
Consequence
Following the investigation into the reported case the Sliding Tube and several Shock
Absorber internal components were unserviceable due to the damage sustained.
In the theoretical extreme case of rupture of all 6 dowel holes, the Sliding Tube would be
retained within the main fitting by the Torque Links. Although retraction of the gear would not
be possible, the gear would still be able to support the aircraft during a subsequent landing.
Solution / Mitigation
Ensure that the servicing is performed correctly in
accordance with the AMM, so that the correct balance
of hydraulic fluid and Nitrogen is maintained at all
times. Keep records of all shock absorber
maintenance.
Upper
Diaphragm
Tube
Retaining Collar
Dowel Pin
Pitot Tube
Sliding Tube
Visible Crack and MPI image of further cracking
Main Fitting
Upper
Bearing
Subassembly
Caused by ineffective maintenance – simple preventive measures can be taken.
67 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.8 – Side Stay
CONTENTS
Lower Side-Stay Detachment
Applicability: All Upper & Lower Side Stay
Attachment Pins :
201521xxx
201584xxx
201659xxx
MLG Cuff Link and Banana Link
Side Stay Double Locking
A/C affected:
A318/A319/A320/A321
Upper Cardan Pin Life Limit
A/C affected:
A320 Pre-EV
68 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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P/N affected:
201163620 only
/02/ Recommended Solutions
2.8 - Lower Side-stay Detachment
Location of Upper
attachment pin
Description / Context
One incident has occurred where the lower side stay
attachment pin detached from the landing gear during
landing.
Consequence
In this case, the aircraft taxied safely to the gate. However,
there is a risk of landing gear collapse.
Location of
Lower
attachment
pin
Root Cause Investigation
• Probable root cause: insecure fastening of the lower side
stay attachment pin.
• After the incident, only the pin was found. The
associated fastening components were not found.
Mitigation / Solution
Operators are reminded that Aircraft Maintenance Manual (AMM) procedures must be
followed to ensure correct assembly and disassembly of the side stay.
Unlocked washer tabs before
locking and sealant application
Follow AMM procedures for assembly and disassembly of side stay
69 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.8 - MLG Cuff Link And Banana Link
Description/ Context
Operators have reported 4 fractures of the cuff subassemblies
Consequence
• Potential for incorrect locking of the lock spring.
• Inspection requirements to Airbus SB A320-32A1224
Root Cause Investigation
• Investigations have shown that the cuff fractures were
due to stress corrosion cracks which were possibly
induced by moisture ingress.
Solution/Mitigation
• MBD SB 200-32-267 & SB 201-32-27 introduces
reinforced cuff and banana links which gives improved
resistance to stress corrosion and improved strength
properties.
Banana Link
Banana Link
Cuff subassembly
Embodiment of MBD SB will reduce the risk of fractures of the cuff and remove the requirement for
inspection
70 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.8 Sidestay Cardan Double Locking
Description/ Context
Status Update
New locking end caps and bolts for the upper
and lower Sidestay Cardan joints - To
introduce double locking to the Joints.
AD released to mandate the installation of new end caps and bolts.
MBD SBs 200-32-315 and 201-32-63 released.
Kits available, contact retrofit@safranmbd.com to place orders –
see table for applicability
• Please note availability of kits is staggered over the AD
Compliance Time (currently June 2021).
Affects all A320/A321 MLG with the exception
of EV
Commercial Policy
Kits discounted by 50% for duration of the
AD compliance time, see SBs for prices.
MLG Type
Kit number
Comments
A320
MAF2175A320-200
Upper and Lower Joints
A321-200
MAF2175A321-200
Upper Joint Only
A321-100
MAF2175A321-100
Upper and Lower Joints
MBD SBs released. Kits available - Contact MBD Retrofit to order.
71 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/02/ Recommended Solutions
2.8 - Sidestay Upper Cardan Life Limit
Description/ Context
Mitigation
During an A320-200 77T main landing gear fatigue test, an
upper cardan PN 201163620 was found with a crack,
emanating from the grease hole / main lug intersection.
Consequence
This condition, if not corrected, could lead to MLG upper
cardan fracture and in worse case MLG collapse.
An AD has been released, it has been decided to reduce the life limit for
certain installations of the P/N 201163620 MLG upper cardan (see below
table for information).
This AD requires implementation of the new life limits, as applicable, and
replacement of any affected MLG upper cardan units that have already
exceeded the reduced limit.
Status Update
AD 2014-0141 released.
MBD SB 200-32-312 has been published with rework instructions to
achieve full life.
Root Cause Investigation
Fatigue crack emanated from grease hole
Crack
Grease holes
AD 2014-0141 and MBD SB 200-32-312 released.
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/02/ Recommended Solutions
2.9 - MLG Lock Stay Actuator Hoses
CONTENTS
Lockstay Actuator Hose Corrosion
Hose Leakage Near Swivel Coupling
Hoses
A/C affected:
A318/A319/A320/A321
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P/N affected:
20165519(3/4/5/6)
/02/ Recommended Solutions
2.9 - MLG Lockstay Actuator Hose Corrosion
Description/ Context
Operators have reported corrosion to hose end
fittings
End fittings
Consequence
Hydraulic leakage
Root Cause Investigation
Hoses
Corrosion was found to be in the threads of the
swivel housing
Solution
MBD SB 200-32-300 and MBD SB 201-32-52
(A321) introduces a more corrosion resistant
material of the end fittings.
Crack on
swivel
housing
MBD SBs introduce new end fittings which are more resistant to corrosion
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/02/ Recommended Solutions
2.9 - MLG Lockstay Actuator Hose Leakage Near Swivel Coupling
Description/Context
2 Cases of Post SB 200-32-300 Lockstay Actuator Hose leakages
near the swivel coupling location on the hose.
Possible Consequence
• If leak occurs whilst aircraft on ground may result in an AOG and
delays to source a spare hose.
• If leak occurs in flight then may result in in-ability to retract MLG and
an in flight turn back.
Root Cause Investigation
The hose leakage on the subject aircraft is a result of an attempt to
undo the 13/16” Hex or 11/16” Hex of the Swivel coupling end fitting to
disconnect the Swivel coupling from the hose socket during AC
maintenance. This joint should only be used during hose production.
Mitigation/Solution
Operators should not use the 11/16” and the 13/16” Hex when
removing or installing the Lockstay actuator hoses . AMM will be
updated to include these notes due Q4 2016.
Swivel coupling
Hose Socket
SimpleMBD
solution
available,new
AMM
to fittings
be updated
risk of future
occurrence.
SBs introduce
end
which to
arereduce
more resistant
to corrosion
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/02/ Recommended Solutions
2.10 - MLG Main Fitting
CONTENTS
Main Fitting Inner Bore Corrosion
A/C affected:
A318/A319/A320/A321
P/N affected:
All PNs
Main Fitting Inner Bore Corrosion RDDAS Guidelines
Main Fitting Inner Bore Corrosion FAQs
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/02/ Recommended Solutions
2.10 - MLG Main Fitting Inner Bore Corrosion
Description/Context
Estimated ~3% of fleet affected and ~50 cases of Main Fitting corrosion have been
reported since the introduction of a modified Lower Bearing with a longer outer liner
in 2008 (MBD SBs 200-32-297 & 201-32-49). All cases have been repairable.
Possible Consequences
•
•
Shock absorber fluid leakage and consequent unscheduled maintenance.
A requirement to perform an on-wing repair, to remove corrosion damage.
• Extreme cases of corrosion may necessitate MRO repair.
Root Cause Investigation
The root cause of the corrosion is a combination of:
• Inherent micro-cracking of the flash chrome plus moisture ingress can
lead to corrosion . This corrosion causes chrome lift/detachment.
• Fretting between the Lower Bearing and Main Fitting, which (in the
presence of lifted/detached chrome) damages the attached flash chrome
and exposes the base metal further.
Mitigation
• Refer to Airbus SIL 32-144 (especially page 45) for Corrosion Prevention
Recommendations.
• On-Wing:
• If you find this damage, make an RDDAS request to MBD AOG CSC
(aogcsc@safranmbd.com) and request the current reporting template.
• RDDAS limitation: next overhaul
• MBD SLs A320-A31 & A321-A19 (application of a CIC Wipe) may be
performed at any convenient opportunity (RDDAS or no RDDAS) to
increase inspection interval.
• Maximum RDDAS inspection interval: 8000FC/48 months.
Solution
At overhaul Main Fittings are modifiable (MBD SB 200-32-371 & 201-32-65):
• Main Fitting bore machined to accommodate a thicker layer of chrome
• Chrome wiped with primer paint to fill surface micro-cracks
This will be embodied on new manufacture in August 2015.
On-Wing MBD SLs A31 & A19 issued Sep. 2014 to apply CIC wipe to area
RDDAS Guide
MISP Closed, Solutions Available
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/02/ Recommended Solutions
2.10 - MLG Main Fitting Inner Bore Corrosion RDDAS Guidelines
General Guidelines
Main Fitting Inner Bore Corrosion RDDASs must take a number of variables into account before a RDDAS can be issued.
FAQs
• Blends in the sealing lands must provide enough material support to maintain the shock absorber sealing function.
• Blends in the locating bore must provide enough support for the lower bearing during landing gear operation and maintain fatigue stresses within acceptable limits,
where the support has been removed or is not sufficient the RDDAS would be rejected and off-wing repaired would be required (including installation of an overseize bearing).
Case
Case Description
Blend Size
Max Depth
Seen
1
Locating Bore Deep Blend
Height 80mm x Width 140mm
0.9mm
2
Primary Seal Land Deep
Blend
Height 37mm x Width 23mm
0.7mm
Blend is near seals and RDDAS is subject to
satisfactory sealing of the shock absorber.
3
Long Blend in Locating bore
Height 50mm x Width 250mm
0.42mm
Remaining section above blend provides support for
bearing.
Case 1
Comments
Case 2
Case 3
Note: this slide is for information only and is not authorisation for future repairs
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/02/ Recommended Solutions
2.10 - MLG Main Fitting Inner Bore Corrosion FAQs
Customer Question (Main Fitting):
Customer Question (Lower Bearing):
I need to repair a pre-SB* Main Fitting (at overhaul) in the area where the
Lower Bearing locates, but the only CMM Repair is for a post-SB* Main
Fitting. How do I process the repair?
* SB 200-32-317 (A320), SB 201-32-65 (A321)
I have repaired a Main Fitting in the area where the Lower Bearing
locates and want to install an oversize Lower Bearing with a “long” outerliner. However, SB 200-32-297 / SB 201-32-49 does not include the P/Ns
of oversize Lower Bearings. How do I proceed?
MBD Response:
MBD Response:
You first need to embody the re-identification aspect of the SB*. In practice,
this means you must assign the applicable post-SB P/N to the Main Fitting,
both in documentation and on the part, in accordance with the SB*
instructions. Then the CMM Repair will be applicable to your Main Fitting.
You first need to embody the re-identification aspect of the SB by
cancelling the strike numbers on the applicable nameplates. Then you
can refer to the CMM Repair for the Main Fitting, where the “Option 2 –
Post SB” table contains the P/Ns of the “long” outer-liner oversize Lower
Bearings.
More FAQs
Main Fitting Flow Chart
Lower Bearing Flow Chart
1. Embody the re-identification aspect of the SB:
1. Embody the re-identification aspect of the SB:
Assign the applicable post-SB P/N to the Main Fitting
(both in documentation and on the part), in
accordance with the SB*.
Cancel the strike numbers on the applicable
nameplates in accordance with SB instructions.
2. Perform the CMM Repair:
2. Refer to the CMM:
Now that your Main Fitting is identified with a postSB* P/N, you can perform the CMM Repair.
Now that your MLG is identified as being post-SB, refer
to the “Option 2 – Post SB” table in the CMM Repair,
which contains the P/Ns of the “long” outer-liner
oversize Lower Bearings.
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/02/ Recommended Solutions
2.10 - MLG Main Fitting Inner Bore Corrosion FAQs
Customer Question (Main Fitting):
Customer Question (Lower Bearing):
Is there any concern that the wet primer will mix with hydraulic fluid?
Is it possible to apply the SB on-wing?
MBD Response:
No, the wet primer application procedure calls for the wet primer to be
wiped ‘dry’. The objective is not for the primer to stay on the surface but
to impregnate the microcracks.
Customer Question (Lower Bearing):
MBD Response:
No because the chrome plating is a shop procedure. See the on-wing
solution (Service Letter) for way forward.
Customer Question (Lower Bearing):
What will be the design in this area for the new EV MLGs?
What is the maximum allowable blend depth for a RDDAS if there are
corrosion findings?
MBD Response:
MBD Response:
Same as existing solution i.e. Thicker chrome plating (a small number of
EV MLGs do not have the solution embodied).
Due to the number of variables (Blend Width, Height, Depth and
Location), MBD is currently processing RDDASs on a case by case
basis.
Customer Question (Lower Bearing):
Does CIC wipe need to be re-applied if the shock absorber is
disassembled for any reason before overhaul?
MBD Response:
MBD recommends the reapplication of CIC wipe in the area at any
convenient opportunity, as a best practice.
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/03/ Best Maintenance Practices
3 - Landing Gear - Best Maintenance Practices
Lubrication of Landing Gears
• 3.1. NLG Lubrication Recommendations
• 3.2. MLG Lubrication Recommendations
• 3.3. General Lubrication Recommendations
• 3.4. Signs of In-Effective Lubrication
• 3.5. Lubrication of Threads
• 3.6. Clay vs Lithium Grease
Cleaning
• 3.6. General Recommendations
General Checks
• 3.7. Sealant
• 3.8. Protective Treatments
• 3.9. Hoses and Harnesses
Effective preventative maintenance will reduce the risk of part degradation and improve gear reliability
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/03/ Best Maintenance Practices
3.1 - NLG Lubrication Recommendations
Upper panel & barrel hinge
pintle
The greasing intervals given in
Airbus MPD are the minimum
requirement. MBD, on advice from
operators has highlighted sensitive
areas where operators may wish to
reduce their greasing intervals
should they feel the need (proactively or through previous
experience).
24/25 GA target lever
pin
Torque links and apex pins
Lower Bearing
Effective greasing will reduce the risk of part degradation and improve gear reliability
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/03/ Best Maintenance Practices
3.2 - MLG Lubrication Recommendations
The greasing intervals given in
Airbus MPD are the minimum
requirement. MBD, on advice from
operators has highlighted sensitive
areas where operators may wish to
reduce their greasing intervals
should they feel the need (proactively or through previous
experience).
Retraction Actuator
Pins
Pintle Bearings Forward and
Aft
Lower Bearing Dowel Pins, particularly
if flying into the CIS region where
weekly greasing is recommended
Very dynamic location and operation on rough
runways and taxiways has been proven to
reduce grease longevity therefore more frequent
grease replenishment is recommended.
Upper and Lower Torque
Links
Effective greasing will reduce the risk of part degradation and improve gear reliability
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/03/ Best Maintenance Practices
3.3 - General Lubrication Recommendations
Lubrication Information:
•
•
•
Greasing operations are expected to fulfill two different functions:
• Lubrication
• Indirect protection of metallic parts against corrosion
Greasing minimises friction in joints and expels trapped moisture dirt and debris from joints interface
locations.
Greasing and lubrication of the landing gear need to be performed as per MPD Greasing intervals as a
minimum
Recommendation during Greasing
•
•
•
Fully replenish all old grease at every greasing interval, by injecting grease until only fresh grease is seen to
extrude (purging) for full grease renewal
• Replenishing grease throughout a path/joint will prevent solidification of the grease inside the greasing
paths
• Note:- This is only possible for joints where grease is expelled externally
Do not mix greases of different types / specifications
• If grease is changed, fully purge joint with new grease and reduce greasing interval for a short period of
time
Use only approved lubricants from the Airbus Consumable Materials List
• Ensure grease is within its shelf life
• Ensure grease is kept in sealed containers before use
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/03/ Best Maintenance Practices
3.4 - Signs of In-Effective Lubrication
Signs of In-Effective Lubrication
Signs that a grease path is blocked
•
•
•
•
•
During Greasing Application extruded grease may
contain debris
Excessively worn protective treatments, chromium
plate and possible exposure of base metal.
Base material may be corroded.
•
•
In-effective lubrication
excessive wear and base
metal exposure.
Grease gun give excessive back pressure
Excessive grease may extrude from around grease
adaptor..
During disassembly greasing path may be visibly
blocked
No grease extrude from joint or orifice
Effective Lubrication,
normal wear.
Blocked Greasing path – lack
of effective lubrication
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/03/ Best Maintenance Practices
3.5 - Lubrication of Threads
•
Application of jointing compound on threads and splines is important to prevent degradation.
•
An application of suitable lubricant/ Jointing compound on to threads before assembly as per
AMM/ CMM practices (i.e Molykote DX paste as per below image) will lubricate the thread
interface and prevent protective treatment damage during assembly.
•
Lubricants and jointing compounds used for this application are not resistant to hydraulic oils
and will absorb moisture over time, so ensure that a fillet of sealant is always present to provide
additional protection.
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/03/ Best Maintenance Practices
3.6 - Clay vs Lithium Grease
MBD has received frequent questions and requests regarding lithium based
greases for use on all families of landing gear.
The Airbus AMM currently allows use of either Lithium or Clay based
greases.
MBD documentation and deliveries currently complies with the grease
specified on the purchase order from the Type Certificate Holder of the
aircraft. For Single Aisle Aircraft this is currently Clay Based Grease Mobil
28.
MBD recognizes that some operators have a preference for Lithium grease
over Clay based grease; however the introduction of Lithium grease into
MBD documentation will not take place until requested by the Type
Certificate Holder.
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/03/ Best Maintenance Practices
3.6 - General Cleaning Recommendations
DO NOT USE Vapour cleaning or high pressure spraying equipment (MBD also recommends operators
DO NOT use low pressure spraying equipment). These cleaning methods lead to potential moisture
ingress, sealant damage and part corrosion in particular:
• Removal of protective treatments and damage to fillets of sealant on Structural Parts resulting
in corrosion
• Moisture ingress inside Interference Fits (Lug and Bush Interfaces) resulting in lug corrosion
• Damage to Electrical Equipment resulting in short circuiting or false indications
• Damage or degradation to Sealed (Hydraulic) Units (see below)
If you do use low pressure spray equipment when washing Sealed
(Hydraulic units) then:
• Do not direct the jet to the gland ID: This could force
water past the scraper seal lead to moisture ingress
result in corrosion on internal parts.
• Do not direct the jet to external valves: this may
remove sealant and lead to moisture ingress.
Follow and use only AMM approved cleaning methods and fluids.
• AMM External Cleaning
• AMM Main Landing Gear Cleaning
Washing of Hydraulic
Units - Do not direct jet to
this location (Gland ID)
88 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/03/ Best Maintenance Practices
3.7 - General Checks - Sealant
• Inspection and repair is recommended at regular intervals and/or when damage is noted during
any visual inspection.
• Visually Inspect joints to ensure sealant is present and forms a continuous unbroken profile.
Any damage to sealant should be repaired / replaced in line with relevant AMM/CMM.
Cracked
sealant could
identify bush
migration /
rotation.
• Cracked sealant could indicated bush/Migration or rotation.
Ensure
sealant is
present and
continuous
• If Migration or bush rotation has occurred then refer to applicable AMM/CMM or approved
documentation (In some cases this is covered in a service bulletin)
89 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/03/ Best Maintenance Practices
3.8 - General Checks - Protective Treatments
•
Protective Treatment prevents base material from corrosion. Any
damage to protective treatment could result in corrosion and part
degradation.
•
Signs that a Protective Treatment is Damaged
• Visual defects present
• Old exuded grease may include particles of protective treatments
• Corrosion / corrosion product evident in the area
• Base material exposed
•
Causes of Protective Treatment Damage
• Ingress of moisture into a joint, Stagnant water in a joint,
Abrasive damage (Internal wear and external chaffing), General
weather damage FOD damage, Chemical damage/attack (deicing fluids, hydraulic fluids, etc), Physical damage from
mishandling
•
Replenishment of Protective Treatments
• Follow relevant AMM/CMM to reapply the protective treatment
90 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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Paint Loss has resulted
in corrosion on this
MLG
/03/ Best Maintenance Practices
3.9 - General Checks - Hoses and Harnesses
• Damage to the Harness and protective treatment could occur when these two components
come in contact with each other during the operation
• When inspecting hoses and harnesses, look out for worn sections, leakages, deformation,
kinks, scratches, FOD / protective treatment damage. Also ensure that the back shells are not
cracked or damaged. If any of these damages are encountered, the part must be replaced,
refer to the relevant AMM / CMM.
• Do not perform unauthorised modifications or repairs to harness and hoses as this can have
unforeseen results and consequences.
91 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Product Information
1. A320/321 Serialisation SBs
2. Restoration Information
3. Tracking the safe life of parts
4. New Products
5. EV Tooling Information
92 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.1 - MLG A320 Serialisation Service Bulletins
 It is a requirement of the Airbus MPD that all the life limited parts can be
tracked
• This was introduced by a number of Service Bulletins:
• 200-32-271 (Retraction actuator pins and forward pintle pin cross bolts)
• Refer to Airbus SB A320-32-1213 for compliance
• Introduction of a new serialised parts from SB 200-32-271 will also accomplish SB
200-32-261
• 200-32-282 (Torque link apex pin nut)
• 200-32-283 (Side stay parts)
• Introduction of the new serialised Cuff and Banana link subassemblies from SB 20032-283 will also accomplish SB 200-32-267
• 200-32-284 (Retraction actuator)
• The Serialisation Service Bulletins include a method to produce the unique tracking numbers
• The operators should make sure that the applicable strike numbers are marked on the strike
plates
Embodiment of MBD SB’s will help to track the safe life of the parts
93 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.1 - MLG A321 Serialisation Service Bulletins
 It is a requirement of the Airbus MPD that all the life limited parts can be
tracked
• This was introduced by a number of Service Bulletins:
• 201-32-29 (Retraction actuator pins and forward pintle pin cross bolts)
• Refer to Airbus SB A320-32-1213 for compliance
• Introduction of a new serialised parts from SB 200-32-29 will also accomplish SB 20132-22
• 201-32-39 (Torque link apex pin nut)
• 201-32-40 (Side stay parts)
• Introduction of the new serialised Cuff and Banana link subassemblies from SB 20132-40 will also accomplish SB 201-32-27
• 201-32-41 (Retraction actuator)
• The Serialisation Service Bulletins include a method to produce the unique tracking numbers
• The operators should make sure that the applicable strike numbers are marked on the strike
plates
Continued
Embodiment of MBD SB’s will help to track the safe life of the parts
94 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.2 - NLG Restoration Information
•
Based on MBD experience and in-service feedback, MBD has issued a SB
which provides the recommended restoration tasks to perform at the end
of the TBO period (during overhaul process)
•
The recommendations provided in this MBD SB advise on the restoration
activity that needs to be performed to maintain continued safe and reliable
operation.
•
2 categories have been defined :
• Concept A => parts requiring a complete overhaul as per the relevant CMM
• Concept B => parts submitted only to visual inspection and tests as per relevant
CMM; if a finding is noticed during visual inspection or the test then the part should
be submitted to a complete overhaul as per relevant CMM
Continued
MBD SB 580-32-3170 provides all restoration tasks to perform on NLG
95 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.2 - MLG Restoration Information
• The Restoration Service Bulletins were produced by
MBD to define the minimum requirements that need
to be achieved at an overhaul
• These Service Bulletins must be used in conjunction
with the Airbus MRBR and MPD documents
• The Service Bulletins list the items that are identified
with a life limitation that require a full restoration
• On condition units that are accepted after a
satisfactory test at overhaul will not have had a full
restoration
MBD SB 200-32-295 and 201-32-48 provides all restoration tasks to perform on MLG
96 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.3 - MLG Tracking the Safe Life of Parts
• The Service Bulletins are issued to help Operators to track the safe life of the parts
• The safe life data is included in the Airbus Airworthiness Limitations Section (ALS) and the SBs
• The data in the MBD SB is in three sections
• Parts which tests indicate have not achieved the full design life are listed in Appendix A,
the Safe Life Limits for these parts are listed in the Airbus ALS Part 1 (ALS Part 4 contains
system equipment).
• Parts which tests indicate have achieved the full design life are listed in Appendix B, the
Safe Life Limits for these parts are listed in the Airbus ALS Part 1 (ALS Part 4 contains
system equipment).
• Parts with a recommended replacement within 60,000 landings are listed in Appendix C of
the MBD SBs, with the recommended replacement data, these parts are not included in
the ALS
MBD SB 200-32-230 and 201-32-08 (A321) will help to track the safe life of the parts
97 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.4 - A320 Landing Gear New Products - Context
•
New NLG and MLG are under development
• Driven by new specifications encompassing product
improvement and new programme requirements
• 1 NLG version (common across all AC variants) and
2 MLG versions (A320 & A321)
• Will be applicable to both current A320 family
aircrafts and the NEO aircraft.
•
The new landing gears are derived from the
current production standards with
improvements where required
Continued
98 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.4 - Interchangeability
• The new gears will be compatible with some existing A320
Aircraft.
• Higher structural requirements mean existing A320 gears are NOT
compatible with A320 NEO airframe.
• MBD and Airbus are working together to deliver the latest
improvements to the existing fleet.
Continued
99 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.4 - NLG & MLG Structural Reinforcements
•
NLG structural improvements
•
•
•
•
•
•
•
Main Fitting
Dragstay
Sliding Tube
Turning Tube
Torque link
Shock absorber internals
Secondary structural items
•
•
(pins, wheel axle nut, uplock assembly…)
MLG structural improvements
• Main Fitting
• Sliding Tube
• Sidestay
Continued
100 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.4 - NLG In-Service Corrosion Protection Improvements
•
Upper Support / column interface
• Change of column material to Corrosion
Resistant Steel
•
Articulation points
• Corrosion inhibitor compound in lug cavities
• Improved bush assembly techniques (thicker
cadmium on bushes and wet primer
assembly)
•
Axle / Sliding Tube (spacer) interface
• Corrosion inhibitor compound / jointing
compound
• Improved sealant scheme
Continued
101 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ A320 Landing Gear New Products
4.4 - NLG Operational Improvements
•
Harness chaffing resolution
• New routing of Upper 1M and 2M harnesses
• New junction box technology
•
Retraction Actuator bearing
• Change of rod material to Corrosion Resistant
Steel
• Caged split spherical bearing
•
Towing indications
• Painted visual indication of the 2 angular limits
Continued
102 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.4 - In-service Corrosion Protection Improvements
•
Bushes
• Change of assembly process to use wet
primer method
•
Main Fitting to Upper Diaphragm
Tube Interface
• New environmental seal
• Improved corrosion prevention methods
applied to area
•
Jacking Dome
• Improved protection scheme and assembly
methods
• Design change to improve drainage
Continued
103 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.4 - MLG Operational Improvements
•
New Upper Bearing Assembly for A320
MLG
• Threaded assembly to harmonize A320 & A321
•
Changeover valve indicator
• Improved visual aid for identification of secondary
seal activation
•
Improved Damper and Torque Link
interface
• New wire inserts
• Longer bolts
104 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.5 – EV Tooling Information
 A320 EV NLG socket for use with new
barrel nut.
 A320 CMM 32-27-70 – T46934
105 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.5 – EV Tooling Information
 A320 and A321 EV MLG Upper Cardan Nut
Socket to torque the new Lower Cardan
Nut
 A320 CMM 32-12-79 – DRT69679
 A321 CMM 32-12-80 – DRT69681
 A320 and A321 EV MLG Lower Cardan Nut
Socket to torque the new Lower Cardan
Nut
 A320 CMM 32-12-79 - DRT69678
 A321 CMM 32-12-80 - DRT69680
106 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.5 – EV Tooling Information
 A320 EV MLG fixture to drill locking plate 55-4505016-
00 for threaded upper bearing assembly.
 CMM 32-12-82 – F28183000
 A320 EV MLG spanner to torque the Upper Bearing
onto the Slider
 CMM 32-12-82 – T47412
Upper Bearing
Locking Plate
 A320 EV MLG threaded
cone to protect sliding tube
threads during lower
bearing
 CMM 32-12-82 – T47411
Sliding Tube
107 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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/04/ Landing Gear Production Information
4.5 – EV Tooling Information
Piston Nut
 A320 and A321 EV MLG torque
adaptor for use on Retraction
Actuator Piston
 CMM 32-31-04 - PN 144465
108 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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END
109 / A320 Family - In Service experience – Landing Gear - Issue 4 - February 2016
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