BARRY CONTROLS AEROSPACE
TECHNICAL PRESENTATION ON
VIBRATION AND
VIBRATION ISOLATION
24/03/2016
BCA PROPIETARY INFORMATION
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Introduction
David Posavec
Eastern Regional Sales Manager
Barry Controls Aerospace
Responsibilities Include:
•OEMs
•Regional & Major Airlines
•Cargo Airlines
•GA & Distribution
•Trade Shows & IA renewals
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Barry Controls Aerospace
• Over 55 years developing and
manufacturing aviation vibration
and noise control solutions
• World’s leading supplier of Engine
and APU Vibration Isolators
– Jet, turboprop, and general
aviation aircraft products
– Manufacture over 5,000
products and hold over 350
PMA’s
– Applications on virtually every
commercial jet aircraft
• Three locations:
– Burbank, California (pictured)
– Toulouse, France
– Hersham, England
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Barry Controls Aerospace
• Proven Supplier
– World’s leader in the design, development, production and support
of state of the art vibration isolation systems.
– Over 55 years of experience in providing main engine and APU
isolation systems for a majority of the world’s commercial and
business aircraft manufacturers.
– Issued first firm order in the industry to outfit a jet carrier’s entire
fleet with an active cabin noise reduction system.
– Service Center direct product support
– ISO-9000 and D1-9000 approved
– Factory direct, product support engineers, field support personnel
and warranty processing.
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Product Line
• Vibration Isolation
– Fixed Wing
– Rotary Wing
• Tuned Mass Absorber
– Passive
– Active (ATMA)
• Other products include: anti-vibration mounts, avionics
trays and racking systems
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Barry Controls Aerospace
• Quality System Approvals
– FAA - PMA/TSO - F.A.R. Part 21
– FAA - Organizational Designated Airworthiness Representative (ODAR)
F.A.R. Part 21.303
– FAA - F.A.R. 145 Repair Station
– FAA - J.A.R. 145 Repair Station
– CAAC - China CCAR 145 Repair Station
– Government - MIL-I-45208A and MIL-Q-9858A
– Boeing - Advanced Quality System AQS/D1-9000A
– Coordinating Agency for Supplier Evaluation (CASE)
– ISO 9001 Compliance
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Barry Controls Aerospace
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Quality System Approvals by Major OEM’s
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Aerospatiale
Airbus
Agusta
B.F. Goodrich
Boeing
British Aerospace
Cessna
Fairchild/Dornier
Fokker
Gulfstream
Lockheed-Martin
Nordam
Northrop
Raytheon Aircraft
Westland Aerospace
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General Aviation Experience
• General Aviation Isolation Systems
– Beech Bonanza, King Air, Queen Air, Musketeer, Travel Air
– Cessna Skyhawk, Stationair, Centurion, Eagle, Conquest
– Maule M4, 5, 6, & 7 series -Mooney Mark, Ranger, Statesman
– Pilatus PC-6, -7, -9, -12
– Piper Aerostar, Apache, Arrow Series, Aztec, Cherokee,
Cheyenne, Comanche, Dakota, Navajo
– Robin, Socata, Transavia, Wassmer, Xian and Zlin
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Business Jet Experience
• Business Jet Engine Isolation Systems
– All Gulfstream Applications, G-II, G-III, & G-IV
– Raytheon Jayhawk, Premier I, 400A, and Hawker Horizon 4000
– Cessna Citation 1, 2, & 3
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Israel Aircraft Industries 1121 & 1123
Sabreliner NA-265-65 & NA-265-75A
Rockwell NA-265-40 & NA-265-60
Lockheed Jetstar
Sino-Swearingen SJ30-2
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Regional Aircraft Experience
• Regional Transport Engine Isolation Systems
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All ATR Applications - ATR42 & ATR72 Series
All BAe/Jetstream Applications - J31, J41, & ATP
All Fokker Applications F50 & F60
Fairchild/Dornier Applications - Metro, Do228, Do328 Turboprop and
Do328 Jet
deHavilland Dash 8 Series 400
Lockheed C-27J
Saab 340
Xian Y7-200A & Harbin Y11-100
CASA C212 & C295
IPTN N250
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Commercial Jet Experience
• Large Commercial Jet Engine Isolation Systems
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Boeing 717
Boeing 727 Series
Boeing 737 Series
Douglas DC-9 Series
Douglas MD-80 Series
Fokker 70 and 100
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Product Experience
1.
MD-80 Aft Isolator
2.
MD-80 Fwd Isolator
3.
727 Aft Isolator Side &
Center Engines
4.
DC-9 Fwd Isolator
5.
DC-9 Aft Isolator
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3
2
5
7
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11
6.
DC-9 Conebolts
7.
MD-80 Conebolts
8.
727 Aft Isolator
9.
737 Fwd Isolator
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10. 737 Aft Isolator
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11. 727 Fwd Isolator
12. A-320 APU Isolator
13. A-300 APU Isolator
14. 747-400 APU Isolator
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Auxiliary Power Unit Experience
• APU Isolation Systems
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Airbus A300, A310, A319, A320, and A340
Boeing 727, 737, 747, 757, 767, and 777
Embraer ERJ-170 and ERJ-190
deHavilland Dash 8-400
Fokker 50 and 100
Lockheed 1011 and C-27
SAAB 340 and 2000
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Vibration
What Causes It?
Vibration in aircraft is caused by asymmetry in:
 Rotating mass
 Aerodynamics
 Power output
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Vibration
Rotating Mass Examples
Examples of a Rotating Mass :
Crankshaft
Propeller
Turbine Disk
Tire/Wheel Assembly
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Vibration
Rotating Mass Asymmetry
Causes Of Asymmetry In A Rotating Mass:
 Imbalance of mass about the axis of rotation
 Eccentricity about the axis of rotation
 Misalignment from the plane of rotation (such as a bent
propeller flange), etc…
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Vibration
Aerodynamic Asymmetry
Aerodynamic:
Asymmetry in an aerodynamic structure that results in an
imbalance of aerodynamic forces can be a source of vibration.
These imbalances can be caused by:
 Dimensional differences as a result of manufacturing tolerances
or repairs
 Asymmetrical airflow to the structure (“P” factor would be an
example)
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Vibration
Power Output Asymmetry
Power Output
Asymmetry in power output is most applicable to
reciprocating engines and would refer to the differences
in power output by each cylinder.
These differences could be attributed:
 Differences in compression
 Uneven fuel delivery
 Weak or non-existent ignition, etc…
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Vibration
Effects of Vibration
Vibration in an aircraft is undesirable due to its detrimental
effects on the aircraft and its occupants. Some of these effects
are:
• High noise level
• Metal Fatigue
• Adhesive Disbond
• Reduced Avionics Life
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Vibration
Engine Vibration Reduction
Various steps can be taken to reduce engine vibration.
• Dynamic balancing of the engine and propeller
• Tighter manufacturing tolerances
• Match balancing of engine components
In reality, the total elimination of vibration is an almost
impossible task.
• Vibration Isolation is a cost-effective alternative
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Vibration
Vibration Isolator
A simple form of vibration isolator is illustrated in Fig. 1. It consists
of a mass (M), a spring (K), and a viscous damper (C). The spring
deflects to prevent a outside force from disturbing the mass, the
damper works to reduce the number of oscillations the spring will
undergo before the system returns to equilibrium.
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Benefit of Engine Isolators
• Offer optimum distribution of engine casing and airframe
loads by design of isolator stiffness and snubbing.
• Thermal expansion of the engine can be taken by
deflection of isolator
• Offer broad-band vibration isolation for high frequency
vibration.
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Benefits of Engine Isolators
• Improves engine blade-out loading and flutter conditions.
• Facilitates engine installation and removal.
• Allows for increased airframe and engine tolerances
using the allowance gained from isolator flexibility.
• Reduces possibility of damage to engine and airframe.
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Vibration
Vibration Isolator Terminology
There are two important terms that describe an
isolator’s characteristics:
 Transmissibility
 Damping
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Vibration
Transmissibility
Transmissibility is defined as the
ratio of the dynamic output
(vibration applied to the
airframe) to the dynamic input
(powerplant vibration).
A typical transmissibility curve is
shown in Fig. 2.
Figure 2
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Vibration
Damping
• Damping refers to the phenomenon by which
energy is dissipated in a vibratory system.
• It is an important property in aircraft engine
isolators because aircraft engines operate over a
wide range of rpm’s.
• As a transmissibility curve shows, when the engine
RPM goes down, the amount of vibration
transferred to the airframe can go up.
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Vibration
Damping
The damping properties of the
elastomers used in aircraft engine
isolators reduce the amount of
amplification that can occur as
transmissibility increases.
(Ref Fig.3).
However, the degree of isolation
provided is also reduced.
Figure 3
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Vibration
Isolator Installation
Typical Dynafocal Mount Installation
• Focuses the centerlines of the isolators at a point slightly ahead of but in the same
plane as the engine’s center of gravity.
•Flight loads are applied equally to each isolator.
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Vibration
Isolator Installation
Typical Bed Mount Installations
Figure A: Semi-focalized Bed Mount
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Figure B: Focalized Bed Mount
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Vibration
Isolator Selection
ISOLATOR SELECTION
 A matter of compromise:
 Softer Elastomer: Better Isolation, More Engine
Deflection

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Stiffer Elastomer: Less Isolation, Less Engine Deflection
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Vibration
Absorption
Tuned Mass Absorption
• In
addition to isolating vibration, it is possible to
“absorb” vibration:
• Absorption is accomplished using a mass and a
spring.
• The spring is tuned to resonate at same frequency as
disturbing frequency
• Resonation is out of phase with disturbing frequency,
resulting in cancellation
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Vibration
Tuned Vibration Absorber
DC-9/MD-80 Tuned Vibration Absorber
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Benefits of Tuned Mass Absorbers
• Effectively attenuates vibration up to 90%.
• Dramatically reduces vibration/noise levels.
• Self-contained units, ready for installation, low
maintenance.
• Relatively low cost, light weight solution in comparison
with other cabin noise reduction solutions.
• Reduces structure displacement and stress, improving
structural fatigue life.
• Improves isolation system performance.
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®
ATMA System
Noise Reduction
System Components
4 N1 Absorbers
4 N2 Absorbers
Controller Box
Harnesses
Sensor Assemblies
Power consumption
5 Amps maximum
30 Watts (or less during
cruise)
Health monitoring function
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®
Installed ATMA System
Noise Reduction
No engine removal required
Overnight installation
No interior modifications
No special tools required
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Aircraft Vibration Isolators
Description and Operation
Typical General Aviation Vibration Isolator
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Aircraft Vibration Isolators
Why bother with Cure Dates?
Elastomers used in Aircraft Vibration Isolators continue to
cure (release chemicals & oils) long after they are
manufactured.
 This can lead to stiffening of the elastomer
 Excessive stiffening can cause the elastomer to be
outside of tolerable spring limits based on design criteria.
 Cure dates ensure elastomers are within tolerable limits
before being installed on aircraft.
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Aircraft Vibration Isolators
Deciphering Cure Dates
Cure Dates are printed on the outside of each BarryMount
package adjacent to the part #
Sample Cure Date: CD 0230
Was manufactured the 30th week of 2002.
Since the elastomer composition may not be readily known
please call Barry Controls Technical Engineering Dept. @
818-973-2524 to determine shelf life or if you have further
questions
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Aircraft Vibration Isolators
Isolator Materials & Cure Dates
Molded assemblies can be made of several materials
depending on their installed environment:
 Natural Rubber (usually black) –5yr Cure Date
 Butyl –10yr Cure Date
 EPDM – 10yr Cure Date
 Chlorylbutyl – 10yr Cure Date
 Chlorylprene –10yr Cure Date
 Nitrile –10yr Cure Date
 Silicone (colors, hi-heat resistant) –20yr Cure Date
 Fluorocarbon –20yr Cure Date
 Metal Mesh – Cure Date N/A
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Aircraft Vibration Isolators
Selection & Replacement Criteria
Do not assume the vibration isolators removed from the aircraft
are the correct part #for that aircraft or that they were
previously installed properly.
 Verify by using updated Barry applicability charts to ensure
FAA/PMA approval for your particular application.
 New FAA/PMAs are granted all the time.
 Do not rely on cross-reference charts.
 Follow the specific installation directions on BCA’s Application
Sheets for the Isolator(s) you are replacing
 The same Barry part # may have different installation
instructions (direction of the shimmed molded assembly) for
different aircraft applications.
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Aircraft Vibration Isolators
Maintenance
Maintenance of Engine Vibration Isolators
Cleaning:
 Wipe Down With A Clean Rag
 Soap and Water Wash
 Isopropyl Alcohol
 No Other Solvents Should Be Used
If Lubricants Or Solvents Are Spilled Onto Isolators,
They Should Be Removed As Quickly As Possible.
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Aircraft Vibration Isolators
On-Aircraft Inspection
An on-aircraft inspection should be performed during:
 Annual or 100 Hour Inspection
The inspection can be accomplished with the isolators
mounted on the aircraft.
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Aircraft Vibration Isolators
On-Aircraft Inspection
The criteria for inspection should include:
 Elastomer Condition
 Elastomer-to-Metal Bond Integrity
 Metal washers (as visible) for corrosion or damage
such as nicks, dings, etc.
 Surrounding structure (such as the cowling, prop
spinner) for damage caused by excessive drift of the
engine.
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Aircraft Vibration Isolators
Bench Inspection
Engine vibration isolators should be removed and inspected under the
following circumstances:
 When an engine is removed for overhaul.
 When sudden stoppage of the propeller or engine occurs.
 When the nacelle engine bay has been exposed to excessive heat (i.e.
engine fire).
 When excessive vibration is experienced or reported.
 Any circumstance not identified above that would indicate the
airworthiness of the isolator(s) may have been compromised (age
weathering, deterioration, etc.).
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Aircraft Vibration Isolators
Bench Inspection
 Removed isolators should be inspected to the same
criteria as installed mounts.
 Two additional checks of the molded assemblies should
also be performed.
 Free height of the molded assembly
 Eccentricity.
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Aircraft Vibration Isolators
Bench Inspection
Free Height
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Eccentricity
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Aircraft Vibration Isolators
Bench Inspection
An additional item to check when inspecting disassembled
isolators is the spacer.
Spacer Types:
 Tubular Metal
 Molded With Tubular Metal Core
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Aircraft Vibration Isolators
Bench Inspection
The spacer should be inspected for:
 Distortion Due to Overtorquing
 Snubbing Marks
 Condition of Elastomer (if applicable)
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Aircraft Vibration Isolators
Replacement
Whenever the above inspections cause a rejection of a
component of an isolator, the isolator must be replaced as an
assembly. Mixing of new and used components is not allowed.
Barry Controls Aerospace also recommends that isolators be
replaced as a set, rather than mixing old and new isolators on an
engine
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Aircraft Vibration Isolators
Replace vs. Overhaul
 Piston Engine isolators are replaceable items due to the relative
inexpensive nature of their metallic components
 Most Turboprop, Business Jet, Regional Airline &
Commercial Aircraft Engine & APU isolators are candidates
for Repair or Overhaul by our FAA Repair Station #
UT3R905L due to the relatively high value of their metallic
components.
 BCA offers Repair & Overhaul of BCA & NONBCA components in our Repair Station directly to operators &
via our Distributor network.
 Please see our Repair Station Capabilities Brochure
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Conebolt Inspection Criteria Service Letters
Issued May 2004
EFFECTIVITY:
CONEBOLT PART#S
R18423-53 & R18424-54
R18423-53 & R18423-54
APPLICATION
Boeing727 with Fedex Hush Kit with
95803-1 isolators
Boeing 727 with 7350000 isolators
R18207-51 & R18206-52
Boeing 727 with K2223 isolators
R18423-2, R18423-49, R18424-2 & Boeing 737 with BCA 5467-1 isolators
R18424-50
R18210-2 & R18211-2
K2219-9SA3, K2219-9SA7, &
isolators
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DC-9 Series (Excluding DC-9-80 & MD-80
Series with BCA K2219-7 isolators
DC-9 & MD-80 with BCA K2219-9
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Conebolt Inspection Criteria Service Letters
Issued May 2004
REFERENCES:
a) Barry Controls Aerospace Component Maintenance Manual
71-20-01 for Type # 7350000
b) Military Specification MIL-S-8879
c) SAE Specification AS8879 (Supersedes MIL-S-8879C)
d) ANSI/ASME Specification B1.3M
e) Federal Standard FED-STD-H28/20B
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Conebolt Inspection Criteria Service Letters
Issued May 2004
BACKGROUND:
Barry Controls Aerospace (BCA) has received powerplant mounting conebolts
used on the JT-8D series of engines back from operators with complaints that
the conebolt does not pass the minimum run-on torque requirement for the
self-locking attach nut. Multiple tries with different attach nuts yielded similar
results.
Inspection of the conebolt’s 0.625-18 UNJF-3A threads found that the parts
had worn and no longer met the requirements of MIL-S-8879C (or it’s
replacement SAE AS8879), which prevented the attach nut meeting it’s
minimum run-on torque.
The wear to the threads is a result of loss of material due to friction from
contact with the nut, rework of the threads with a thread chaser or file, or bolt
“stretch” due to repeated torquing.
BCA would like to clarify the inspection requirements outlined in MIL-S-8879C
(& SAE AS8879) to ensure that the conebolts are properly inspected and
overhauled in accordance with the BCA Component Maintenance Manual 71BCA PROPIETARY INFORMATION
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20-01 for Type # 7350000.
Conebolt Inspection Criteria Service Letters
Issued May 2004
Paragraph 4.4.2 of MIL-S-8879 (& paragraph 4.1, System 22, of SAE AS8879)
outlines the thread’s characteristics that must be inspected to ensure
compliance (Note: Application category for conebolts is “Other Thread”).
They are:
a) “GO” functional diameter
b) Pitch diameter size
c) Major diameter size
d) Minor diameter size
e) Root radius
The acceptable methods and tools used to inspect these characteristics are
presented in FED-STD-H28/20 (or ANSI/ASME B1.3M). Please note that a
“GO/NO-GO” ring gage set is not capable of measuring all of the dimensions
listed above.
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Conebolt Inspection Criteria Service Letters
Issued May 2004
OPERATOR ACTION:
Due to the critical function of the conebolt, Barry Controls Aerospace
recommends that operators take the following actions:
•
Operators performing their own conebolt overhauls and repairs should review
the MIL-S-8879C (or SAE AS8879) specification to ensure that the conebolts
threads characteristics listed in this specification are being inspected using
the methods prescribed by FED-STDH28/20 (or ANSI/ASME B1.3M).
•
Operators procuring overhauled conebolts from third-party agencies or
having third-party repair agencies perform their conebolt overhauls and
inspections should verify that the conebolt’s threads characteristics outlined
in MIL-S-8879C (or SAE AS8879) are being inspected using the methods
prescribed by FED-STD-H28/20 (or ANSI/ASME B1.3M).
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Conebolt Inspection Criteria Service Letters
Issued May 2004
Barry Controls can also perform overhauls or provide rebuild/exchanges
of conebolts with all units having the threads inspected to the
requirements of MIL-S-8879 (or SAE AS8879) and using the methods
prescribed by FED-STD-H28/20 (or ANSI/ASME B1.3M).
For any questions, contact:
Barry Controls Aerospace
4510 Vanowen Street
Burbank, California 91505 USA
(818) 843-1000
FAX: (818) 845-6978
SITA: BURBCCR
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Questions
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