Naval Aviation Maintenance Program for Hydraulic Contamination and
Control
References:
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OPNAVINST 4790.2G, Volume V, Chapter 6: Establishes
policy, responsibilities, and requirements for
implementing and maintaining techniques to achieve a
satisfactory level of hydraulics system purity.
NAVAIR 01-1A-17, Aviation Hydraulics Manual
NAVAIR 01-1A-20, Aviation Hose and Tube Manual
NAVAIR 17-15E-52, Hydraulic Fluid Contamination
Analysis Kit Part Number 57L414.
NAVAIR 17-15-521, Particle Counter Manual
Aircraft/Support Equipment (SE) Maintenance
Instruction Manuals (MIMs) and Maintenance Requirement
Cards (MRCs).
Objectives:
The Hydraulic Contamination Control Program
a. Establishes policy, responsibilities, and
requirements for implementing and maintaining techniques to
achieve and maintain a satisfactory level of fluid purity
in hydraulic systems and provide for safe and efficient
operation of naval aircraft, weapon systems, and Support
Equipment.
b. Ensures hydraulic fluids are maintained within
acceptable contamination limits through an aggressive
hydraulic fluid surveillance program, with sampling/testing
accomplished at the activity level.
Background:
Hydraulic components and lines are an integral part of
aircraft flight control systems. Systems hydraulic fluid
is used to power flight control surfaces, landing gear
retractions and extension, brakes, and the movement of
other critical components.
Any hydraulic failure can
result in the loss of capability to launch, recover, and
sustain controlled flight of an aircraft. In the newer
aircraft such as the F/A-18, an increased number of
hydraulics systems are used. The following data reflects
the cost associated with loss of hydraulic systems due to
contamination or a hydraulic related mishap:
Cost of Hydraulic Components
$
24,470.00
Requiring Replacement
Manhours To Purge and Repair
Cost of F/A-18C
13.50
35,000,000.00
Both military and civilian aviation communities closely
monitor the quality of their hydraulic systems. For
commercial aircraft specific minimum acceptable criteria
for quality and recommended intervals for testing are
provided by the manufacturer upon delivery of the aircraft
to the customer. In military aircraft similar criteria are
developed by the OEM, approved by NAVAIRSYSCOM, and
provided to the fleet in T/M/S specific technical manuals.
Stringent contamination control is required at all levels
of maintenance to ensure flight safety and the highest
degree of hydraulic system readiness. Hydraulic fluid
contamination causes hydraulic system and component
failures and presents a serious threat to flight safety.
Typical contaminants include metallic and nonmetallic
debris (self-generated and externally introduced), water,
or other foreign fluids, all of which serve to degrade
hydraulic system performance and component life. A
complete particulate categorization appears in NAVAIR 011A-17. Maximum acceptable hydraulic fluid particulate
contamination levels are Navy Standard Class 5 for aircraft
and Navy Standard Class 3 for SE.
Testing for hydraulic contamination is conducted using a
patch test methodology with either a patch test kit or a
particle counter. In most cases the test is a conditional
inspection (e.g. when the asset is transferred or received,
when a major hydraulic component is removed and replaced,
or when checked out for use). However, a patch test is
conducted during an aircraft phase inspection. The
hydraulic sample is drawn from the sample point designated
in the T/M/S Maintenance Instruction Manual (MIM) into a
container with a filter (patch) assembly attached. The
patch is then analyzed by the individual to determine
evidence of contamination. If using an analysis kit, the
inspection is a visual comparison to standards.
If using
a particle counter, the analysis is provided automatically
by the machine.
Effectiveness:
NAVAIR has
program at
safety and
due to the
surface.
maintained a stringent contamination control
all levels of maintenance to ensure flight
the highest degree of hydraulic system readiness
high risk of losing control of a flight control
The effectiveness of the hydraulic contamination program is
measured in the mishap program data. The hydraulic
contamination data was obtained from mishaps where the
hydraulic fluid was contaminated, and mishaps where
components had failed and then contaminated the fluid. The
data contains no mishaps due to hydraulic fluid leaks. The
small number of mishaps indicate the effectiveness of an
aggressive hydraulic contamination program.
Class of
Mishap
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
A
B
1
C
HAZARD
1
1
2
1
2
2
3
3
2
1
Analysis:
The Hydraulic Contamination Control Program requirements
are listed below. The responsibilities are listed by the
individual within a squadron or intermediate level
maintenance facility who is responsible for completing the
task and classified into the four categories requested. The
manhour estimates are based on a 10-12 aircraft F/A-18C
squadron with 180 sailors assigned to the maintenance
department and a 420 person AIMD Afloat CVN with 400
persons assigned.
PROGRAM ELEMENT
ELEMENT
IMPACT
Maintenance Officer (MO):
Manhours
expended
Administrative:
-Designate, in writing, a Hydraulic
Contamination Control certified individual as
Hydraulic Contamination Control Program
manager and designate/authorize personnel to
perform hydraulic sampling and contamination
analysis. (1 designation/yr)
Admin:
<.001 Hours
per day.
-Develop local command procedures. (1
time/chgs as required)
Program Manager:
Administrative:
- Ensure all personnel authorized to conduct
aircraft/SE hydraulic systems sampling and
analysis have completed the Hydraulic
Contamination Control Qualification/
Certification Worksheet and are designated
using the Hydraulic Contamination Control
Designation. (15 min/month)
- Maintain a program file listing applicable
POCs, all assigned equipment requiring
hydraulic sampling, program related
correspondence and message traffic, copies of
the Hydraulic Contamination Control
Designation for all personnel authorized to
perform sampling/analysis and applicable
references or cross reference locator sheets.
(update as required)
- Ensure an adequate number of personnel are
certified in hydraulic contamination control.
Training:
-Provide indoctrination and follow-on training
to personnel relating to their
responsibilities regarding the Hydraulic
Contamination Control Program. (initial
training per individual 1 hr/ follow-on as
Manhours
expended
Admin: <.1
Train: <.01
Hours per
day.
required)
Quality Assurance (QA) Officer:
Administrative:
- Designate, in writing, a QAR as the
Hydraulic Contamination Control Program
Monitor. (1 designation/yr)
Program Monitor:
Assessment:
- Verify that aircraft and SE hydraulic
systems filters are changed, and sampling and
analysis conducted per NAVAIR 01-1A-17,
MIMs/MRCs, and pre-operational requirements.
(as required)
Manhours
expended
Admin:
<.001 Hours
per day.
Manhours
expended
Assessment:
<.2
Admin: < .3
Hours per
day
- Observe sampling and analysis techniques
periodically, as well as during work center
audits. (as required)
- Check hydraulic work center spaces for
cleanliness, safety precautions, SE upkeep and
abuse, facility adequacy, use and availability
of authorized materials, and compliance with
applicable hydraulic maintenance technical
data. (daily)
Administrative:
- Be qualified to perform hydraulic sampling.
- Perform audits using CSEC. (annual)
- Maintain a Hydraulic Contamination Control
Trend Analysis Chart for each assigned
aircraft and SE requiring hydraulic sampling.
(30 min/wk)
- Develop an open-book written examination for
the Hydraulic Contamination Control Program.
- Review the test annually.
- Assist in preparing NAMDRP reports.(as
required)
Maintenance/Production Control personnel:
- Ensure hydraulic samples are obtained and
analyzed during acceptance of assigned
Manhours
expended
Admin: <.1
aircraft and SE. (as required)
- Ensure the Hydraulic Contamination Control
Trend Analysis Chart is included in the
aircraft logbook Miscellaneous/History (OPNAV
4790/25A) and SE Custody and Maintenance
History Record (OPNAV 4790/51) upon transfer
of aircraft and SE. (as required)
Hours per
day.
- Ensure appropriate aircraft logbook and SE
record entries are made for hydraulic samples.
Includes verifying hydraulic samples are
recorded for aircraft and SE transferred from
a depot or commercial repair activity. (as
required)
Logs and Records personnel:
- Place the previous and current Hydraulic
Contamination Control Trend Analysis Chart
with the aircraft logbooks prior to aircraft
transfer. (as required)
- Make an entry in the Miscellaneous/History
(OPNAV 4790/25A) section of the aircraft
logbook when hydraulic system sampling reveals
Navy Standard Class 5 contamination is
exceeded, or evidence of water, or any other
form of contamination requiring
decontamination per NAVAIR 01-1A-17. (as
required)
- Enter in the Miscellaneous/History (OPNAV
4790/25A) section all hydraulic system
sampling results that occur from aircraft
acceptance from a depot, commercial repair
activity, or another reporting custodian. (as
required)
- Place the previous and current Hydraulic
Contamination Control Trend Analysis Chart
with the SE Custody and Maintenance History
Record (OPNAV 4790/51) prior to SE transfer.
(as required)
- Make an entry in the SE Custody and
Maintenance History Record (OPNAV 4790/51)
Miscellaneous History Record section when
hydraulic sampling reveals Navy Standard Class
3 contamination is exceeded, or evidence of
Manhours
expended
Admin:
<.2 hours
per day.
water, or any other form of contamination
requiring decontamination per NAVAIR 01-1A-17.
(as required)
- Enter the results of Hydraulic system
sampling in the SE Custody and Maintenance
History Record (OPNAV 4790/51) during SE
acceptance from a depot, commercial repair
activity, or another reporting custodian. (as
required)
Work Center Supervisor:
Operational:
- Maintain high standards of housekeeping
where hydraulic maintenance/sampling is
performed. (daily)
- Ensure fittings, lines, and components are
capped/plugged immediately (using approved
closures), and are handled and stored in a
manner that prevents damage and contamination
whenever aircraft/SE hydraulic system
integrity is broken. (daily)
- Ensure hydraulic fluid analyses is performed
per NAVAIR 01-1A-17, MIMs/MRCs, equipment preoperational requirements, and during aircraft
and SE acceptance inspections and report
suspected contamination to Maintenance/
Production Control and QA. (as required)
- Ensure all hydraulic component/system
repair, disassembly, inspection, re-assembly,
and testing are conducted per NAVAIR 01-1A-17
and NAVAIR 01-1A-20.
- Report suspected contamination to
Maintenance/Production Control and QA.
Training:
- Ensure NAVAIR 01-1A-17 and NAVAIR 01-1A-20
are required reading for indoctrination
training for those personnel working on
hydraulic systems. (as required)
Administrative:
- Ensure all hydraulic samples performed are
sent to QA for hydraulic contamination control
Manhours
expended
Operation:
<.3
Train: <.1
Admin: <.1
Hours per
day.
trend analysis.
Work Center Technician:
- Ensure hydraulic fluid analyses is performed
per NAVAIR 01-1A-17, MIMs/MRCs, equipment preoperational requirements, and during aircraft
and SE acceptance inspections and report
suspected contamination to Maintenance/
Production Control and QA. (as required)
- Prior to sample processing examined fluid
for free water. Let sample sit for 10 min and
check for visible water droplets in sample. If
water observed, take another sample and if it
still exists initiate corrective maintenance.
- Take hydraulic samples:
-
Place hydraulic sample bottle at hydraulic
sampling port on aircraft or supporting
equipment servicing hose. Draw sample into
bottle.
-
Prepare filter holder assembly in kit and
install the funnel assembly and holder
support assembly. Connect tube and adapter
to filter assembly.
-
Ensure all components are cleaned with
filtered solvent.
-
Place filter membrane on top of the wire
mesh filter support screen. Clean again with
solvent.
-
Shake the sample fluid bottle to distribute
uniformly its particulate content.
-
Pour exactly 100 ml of fluid in test kit
cylinder and then pour into the kit funnel.
-
Operate the syringe in a slow pumping manner
drawing a vacuum for filtration. Carefully
observe the filtration process. Add
additional fluid from sample.
-
When filtration is complete, inspect the
filter surface. Continue processing fluid
through filter.
-
When complete remove funnel and filter
membrane.
Manhours
expended
Operation:
<.75
Hours per
test.
-
Place filter on Petri slide and let dry.
-
Visually compare with contamination
standards by comparing the shade and color
of the test patch. Check for free water.
Second sample will be required if first
sample is not satisfactory.
-
Filter bowl patch residues should be
evaluated qualitatively based upon
requirements of applicable manuals and
utilize experience relative to normal
contaminates for specific aircraft systems.
This step is performed when it is necessary
to analyze and identify suspected component
failure. This step requires considerable
experience.
-If an electronic particle count (laser)
system is used it takes approximately 10 min
vice 45. The following steps are:
-
Open and inspect laser system. Place on
flat, level surface.
-
Reject sample having visible sediment, gels
or water.
-
Shake sample for 1 minute.
-
Fill ultrasonic bath with water. Add 2 drops
of liquid had soap to aid in degassing
process. Insert bottled sample. Run for 30
seconds and remove bottle.
-
Place the sample in the monitor plexiglass
door.
-
Place slipping dip tube into bottle and turn
on flush light. Wait 3.5 minutes. Turn to
test stage and run for another 3.5 minutes.
-
The monitor will count water droplets, air
bubbles and solid particles in the hydraulic
fluid. Results will be printed in graph
format.
- Ensure all internal and external hoses on
aircraft, SE units used to apply pressure to
aircraft systems, and SE servicing units are
marked/etched per NAVAIR 01-1A-20 or
applicable MIMs/MRCs.
- Report suspected contamination to
Maintenance/Production Control and QA.
Total Admin:
.802
Total Operational: .75*
*(based on 1 patch test)
Total Training:
.11
Total Assessment: .20
Total
Manhours:
2.062 Hours
per day. *
Recommendations :
This is a crucial program to the safety of Naval Aviation.
The trending of data allows the activity to prevent the
occurrence of a costly repair or mishap. Due to the safety
of flight elements and the potentially high cost associated
with a mishap, it is recommended that the Hydraulic
Contamination Program not be deleted from the OPNAVINST
4790.2G and that all program requirements be retained with
the exception of those for which a NAMP change has already
been submitted.
A proposed NAMP change has been submitted to modify the
qualification requirement for those activities that operate
and utilize a Laser Particle Counter. Unlike the Hydraulic
Fluid Contamination Analysis kit, the Laser Particle
Counter is an automated system that requires no
interpretation of the sample by the operator. The unit
determines the specific classification of the sample by
simply extracting the sample from the specimen bottle and
analyzing it internally. The simplicity of operating the
Particle Counter makes it unnecessary to require an
analysis section in the qualification process.
Requirements for operating the particle counter are covered
in the system course and do not require separate OJT as
part of the qualification process.
CURRENT INITIATIVES:
a. NAVAIR has procured a new item of support
equipment, the laser particle counter, for use in the
Hydraulic Contamination Program at both the intermediate
and organizational levels of maintenance. This item
dramatically reduces the manhour expenditure in an
activity. The machine vice the sailor performs the
analysis portion of the sampling process and provides a
written copy of the results. Most AIMDs currently have the
item and squadrons are intended to receive it. In those
activities already in receipt of the item, a 30 minute
reduction in manhours per patch test have been realized.
This change equates to an anticipated 21 manhour savings
per month in an F/A-18 squadron which typically averages 42
samples in a 30 day timeframe and a 104 manhour savings in
an AIMD ashore which would typically process 145 samples
per month in the IM2 Division and 62 samples per month in
the IM4 Division.
b. Many of the administrative functions associated
with qualification/certification on this program will be
reduced with the full fleet introduction of the Aviation
Maintenance Training Continuum System (AMTCS) ASM Module at
the organizational level. The ASM Module will
automatically track the qualification and training of the
individual sailor through the use of a relational data
based which links Master Tasks Lists, NALCOMIS data on
maintenance actions, service record information, and
medical certifications.
c. The NALCOMIS Optimized upgrade will include a
digital logbook and configuration management through a
relational database. NALCOMIS is the primary Maintenance
Information/Data System for aviation maintenance and
supply. The Optimized NALCOMIS system for the
organizational level has been prototyped on both coasts and
fleet implementation is scheduled to commence 4th Qtr FY00.
It is planned that the upgrade will incorporate the
capability to automatically compile and track the hydraulic
contamination data currently in the ADB. The Optimized
NALCOMIS upgrade will greatly reduce the manhours required
for administrative tasks in not only this program but all
NAMP program areas through the effective use of a
relational data base and real time up line data
replication.