Lubrication

and Servicing
Introduction
The visual inspection is required to determine the current
condition of the aircraft and its components. The repair of
discrepancies is required to bring the aircraft back up to
airworthy standards. In an effort to keep the aircraft in
airworthy condition, the manufacturer may recommend that
certain services be performed at various operating intervals.
While servicing and lubrication are often conveniently
accomplished during an inspection, they should not be
considered a part of the inspection itself.
Lubrication
As is true of any machinery where moving parts bear against one another, lubrication
is required at many locations in an aircraft. The type of lubrication needed at each
point is determined by factors such as the type of bearing, the bearing loads, the
frequency and speed of movement, the temperatures at the bearing, and the materials
in contact. Lubricants used in aircraft may include ordinary lubricating oil, lightweight
lubricating oil, various weights of greases, high-pressure (HP) grease, low-temperature
grease, high-temperature grease, graphite, silicone, and other specialized lubricants.

The frequency of lubrication for each point in an aircraft is specified by the

manufacturer, along with the type of lubricant, the method of application, and any
special instructions. This information is provided in the manufacturer’s maintenance
manual for each model of aircraft.

Commercial airlines develop their own schedules and procedures for lubricating their
aircraft, typically as part of a continuous airworthiness maintenance program. For light
airplanes, lubrication information is often presented in the form of charts and tables.
Best Practices in Applying Lubricants
1. Maintain Cleanliness: Keep lubricants and dispensing equipment clean. Use only
one type of lubricant per grease gun or oil can.
2. Proper Storage: Store lubricants in a protected area and keep containers closed
when not in use.
3. Prepare Surfaces: Wipe grease fittings, oil holes, and other lubrication points with
clean, dry cloths before applying lubricant.
4. Vented Bearings: For vented bearings, inject grease until all old grease is expelled,
unless otherwise specified.
5. Sealed Bearings: Handle sealed bearings with care to avoid dislodging seals.
6. Ensure Coverage: Move parts, if practical, to ensure thorough lubrication.
7. Clean Excess: After lubrication, remove any surplus lubricant from all surfaces
except the actual working parts.
Lubrication chart

Lubrication charts guide

the entire lubrication
process, detailing lubricant
requirements for all parts
of the machine, including
hard-to-reach areas. For
light airplanes, lubrication
information is often
presented in charts and
tables, specifying every
detail and measure
needed.
Information and
instructions for
the lubrication
chart
Parts
nomenclature
for the
lubrication
chart
How to read
the chart.
Servicing Aircraft
Servicing aircraft requires great care and attention to detail, regardless of the type of
aircraft being serviced or the particular service being performed. The servicing of
particular aircraft and their components is usually described in great detail in the
manufacturers’ maintenance and service manuals. Instructions given in these manuals
should be followed for the satisfactory and safe performance of aircraft.
Engine-Oil Service
For Small Aircraft
1. Daily/Pre-flight Oil Quantity Check:
Use the dipstick to check oil levels.
Ensure oil is at or above the minimum level; add oil if necessary.
Do not exceed the maximum oil level mark.
2. Adding Oil:
Ensure proper foaming space is maintained.
Follow manufacturer’s instructions for oil type and quantity.
3. Specific Instructions (e.g., Cessna Model 421):
Check oil level before each flight.
Maintain oil level between 9 and 13 quarts.
Use SAE 30 oil below 40°F and SAE 50 above 40°F.
During the break-in period (first 50 hours), add straight mineral oil.
Use SAE 10W30 for cold weather.
Switch to detergent/dispersant oil (MHS-24A) after the first 50 hours.
4. Regular Oil Changes:
Change oil every 50 hours of operation or every 4 months.
Clean oil screens and replace filters during oil change.
If oil appears dirty, change it regardless of time or hours of operation.
Engine-Oil Service
For Gas-Turbine Engines
1. Oil Quality Check:
Perform chemical tests to determine oil quality.
Change oil based on test results, not fixed intervals.
2. Adding or Changing Oil:
Ensure the correct type and grade of synthetic lubricant (MIL-L-
7808 or MIL-L-23699) is used.
Prevent spillage and avoid skin contact with synthetic lubricants.
If contact occurs, wipe off immediately and wash the area with soap
and water.
3. Follow Approved Procedures:
Adhere to the airline’s approved service and maintenance
procedures.
Collaborate with engine and aircraft manufacturers for updated
procedures.
Engine-Oil Service

General Tips
Storage and Handling:
Store lubricants in a protected area and keep containers closed
when not in use.
Use clean, dry cloths to wipe lubrication points before applying oil.
Safety:
Wear appropriate PPE when handling lubricants.
Dispose of used oil and filters according to environmental
regulations.
Servicing Brake and Hydraulic Systems
General Guidelines
1. Follow Manufacturer’s Instructions:
Always refer to and comply with the manufacturer’s service manual and
instructions for specific procedures.
2. Service Intervals:
Perform regular servicing at intervals not less than 100 hours of operation,
unless specified otherwise by the manufacturer.

Fluid Checks and Maintenance

1. Fluid Level Check:
Inspect fluid levels regularly and ensure they are within the specified range.
2. Adding Fluid:
Verify and use the correct type of fluid as specified by the manufacturer.
Warning: Using the wrong fluid requires draining, flushing the system, and
possibly replacing all seals.
Servicing Brake and Hydraulic Systems
System Flushing
1. Flushing Procedure:
For systems using petroleum fluids:
Use petroleum solvents to flush the system.
For systems using synthetic, fire-resistant fluids:
Caution: Do not mix with petroleum fluids to avoid damage.

System Integrity and Safety

1. Seal Inspection and Replacement:
Check seals for wear and damage during servicing.
Replace seals as needed, especially after incorrect fluid usage or system
contamination.
2. Preventing Fluid Contamination:
Ensure clean handling and storage of fluids.
Use proper tools and containers to avoid contamination.
Servicing Brake and Hydraulic Systems
Special Considerations for Large Aircraft
1. Synthetic Fluids:
Be aware that many large aircraft use synthetic, fire-resistant hydraulic fluids.
Important: Never mix synthetic fluids with petroleum-based fluids to avoid
severe system damage.

Final Checks
1. Operational Check:
After servicing, perform a functional test of the brake and hydraulic systems to
ensure proper operation.
Look for any signs of leaks, abnormal noises, or other issues.
2. Documentation:
Record all maintenance actions in the aircraft’s maintenance log, noting the
type of fluid added and any other relevant details.
Oxygen-System Service
General Guidelines

1. Replace Oxygen Supplies:

Monitor oxygen-pressure gauges and replace supplies when low.
2. Use Breathing Oxygen Only:
Service oxygen bottles/tanks exclusively with breathing oxygen.

Lubrication
1. Approved Lubricants:
Avoid oils, greases, or petroleum products for parts or fittings.
Use only approved oxygen-system lubricants (e.g., MIL-T-5542-B
or equivalent).
Oxygen-System Service
Servicing Compressed Gaseous Oxygen Systems

1. Replenish Oxygen:
Use an oxygen-service unit with breathing oxygen.
Connect the ground-service unit to the remote fill line.
Open necessary valves carefully to allow oxygen flow.
2. Monitor Pressure:
Observe oxygen pressure during service to prevent overfilling.
3. Safety Precautions:
WARNING: Avoid sparks and keep fire, including cigarettes, away.
Inspect the filler connection for cleanliness before use.
Ensure hands, tools, and clothing are free of grease and oil.
Open and close oxygen valves slowly during filling.
Oxygen-System Service
Servicing Compressed Gaseous Oxygen Systems

1. Replenish Oxygen:
Use an oxygen-service unit with breathing oxygen.
Connect the ground-service unit to the remote fill line.
Open necessary valves carefully to allow oxygen flow.
2. Monitor Pressure:
Observe oxygen pressure during service to prevent overfilling.
3. Safety Precautions:
WARNING: Avoid sparks and keep fire, including cigarettes, away.
Inspect the filler connection for cleanliness before use.
Ensure hands, tools, and clothing are free of grease and oil.
Open and close oxygen valves slowly during filling.
Oxygen-System Service
Servicing Chemical-Oxygen Generator Systems
1. Chemical-Oxygen Generators:
Replace the sodium chlorate core as needed.
Ensure the new core is properly installed and functioning.

Final Checks
1. Operational Check:
After servicing, perform a functional test of the oxygen system.
Ensure there are no leaks and that the system operates correctly.
2. Documentation:
Record all maintenance actions in the aircraft’s maintenance log,
noting the type and quantity of oxygen added or any parts
replaced.
Servicing Batteries
In servicing batteries, it is most important to know whether a
battery is a lead-acid type or an alkaline type, such as a nickel-cadmium
battery. Service procedures for the different types vary considerably. The
service manual or the instructions for the battery should be consulted
unless the technician is thoroughly familiar with the procedure.
Servicing Batteries
Lead-Acid Battery Maintenance Checklist
Pre-Check Preparation:
1. Gather necessary materials: distilled water, baking soda, water,
hydrometer.
2. Ensure safety gear is available, including gloves and eye protection.

Visual Inspection:
1. Check all battery connections for cleanliness and tightness.
2. Verify fluid level is above the baffle plates but not overfilled.
3. Look for signs of corrosion on battery terminals and connections.

Fluid Level Check:

1. If necessary, add distilled water to maintain proper fluid level.
2. Do not overfill the battery to prevent spillage.
Servicing Batteries
Lead-Acid Battery Maintenance Checklist
Hydrometer Test:
1. Perform a hydrometer check to determine battery charge percentage.
2. Interpret hydrometer readings accurately.

Corrosion Treatment:
1. Prepare a solution of baking soda and water to the consistency of thin cream.
2. Apply the solution to corroded terminals and connections.
3. Avoid letting the solution enter the battery.
4. Repeat application until bubbling action ceases.
5. Wash the battery and surrounding area with clean water to remove residue.

Post-Check Verification:
1. Ensure all connections are secure and corrosion-free.
2. Confirm fluid level is within the recommended range.
3. Dispose of any waste materials properly.
4. Record maintenance activities in the aircraft logbook.
Servicing Batteries
Nickel-Cadmium Battery Servicing Checklist
Pre-Service Preparation:
1. Gather necessary materials: distilled water, soap, water, cleaning tools, torque
wrench.
2. Ensure safety gear is available, including gloves and eye protection.
3. Refer to the battery manufacturer’s instructions for specific procedures.

Electrolyte Level Check and Cleaning (Every 100 Hours or 30 Days):

1. Open battery case following manufacturer's instructions.
2. Check electrolyte level in each cell and top up if necessary with distilled water.
3. Clean battery and filler-vent plugs using appropriate cleaning tools.
4. Ensure filler-vent plugs are securely tightened after cleaning.

Cell Vent Inspection:

1. Periodically check cell vents to ensure they are clean and open.
2. Remove any obstructions that may impede venting.
3. Verify proper ventilation to prevent excessive internal cell pressure and leaks.
Servicing Batteries
Nickel-Cadmium Battery Servicing Checklist
Cell Replacement Procedure:
1. Only remove a cell from the battery case if a replacement is immediately available.
2. Loosen vents before cell replacement to prevent remaining cells from swelling.
3. Follow manufacturer's instructions for proper cell replacement procedure.

Terminal Screw Torque Check:

1. Check torque of terminal screws securing cross-links connecting cells.
2. Adjust torque according to manufacturer’s specifications if necessary.
3. Ensure proper connection and prevent loosening during operation.

Carbon Deposit Inspection and Cleaning:

1. Check for carbon deposits on cross-links and between them and the battery case.
2. If deposits are present, clean affected areas using appropriate cleaning tools.
3. Ensure thorough cleaning to maintain proper conductivity.
Servicing Batteries
Nickel-Cadmium Battery Servicing Checklist
Oil Contamination Inspection and Remediation:
1. If oil is present in the battery, remove all cells from the case.
2. Inspect all rubber parts for deterioration and replace damaged parts.
3. Use soap and water to remove oil from cells and battery case.
4. Ensure thorough cleaning to prevent further contamination and maintain safety.

Storage Precautions:
1. Store nickel-cadmium and lead-acid batteries separately to prevent mutual
contamination.
2. If stored in open containers, ensure nickel-cadmium electrolyte is protected from
absorbing carbon dioxide by using closed storage containers.

Post-Service Verification:
1. Double-check all connections, vent plugs, and cleanliness.
2. Confirm proper electrolyte levels in each cell.
3. Record maintenance activities in the aircraft logbook, noting date and details of
servicing.
 Aircraft Tire Maintenance Checklist
Pre-Service Inspection:
1. Visually inspect tires for cracks, breaks, or signs of damage.
2. Check tire pressure using an appropriate gauge.
3. Ensure proper tire inflation according to aircraft specifications.

Tire Rotation:
1. If necessary, reverse tires on the wheels to promote even wear.
2. Follow manufacturer's guidelines for tire rotation intervals.

Wheel Balancing:
1. Ensure all tires and wheels are balanced before installation.
2. Check balance periodically and rebalance if necessary to prevent vibration during
operation.

Tire-Wheel Relationship:
1. Maintain the correct relationship between tire, tube, and wheel during reinstallation.
2. Ensure proper alignment to prevent uneven wear and potential failures.
Aircraft Tire Maintenance Checklist

Takeoff and Landing Considerations:

1. Be aware that tires may experience slight growth during landing due to shock load.
2. Monitor tread wear to ensure balanced growth and maintain proper tire diameter.

Post-Service Verification:
1. Double-check tire pressure and visual condition after service.
2. Confirm proper installation and alignment of tires on the wheels.
3. Record tire maintenance activities in the aircraft logbook, including tire pressure,
rotation, and any observed issues.
Aircraft Tire Maintenance Checklist

Takeoff and Landing Considerations:

1. Be aware that tires may experience slight growth during landing due to shock load.
2. Monitor tread wear to ensure balanced growth and maintain proper tire diameter.

Post-Service Verification:
1. Double-check tire pressure and visual condition after service.
2. Confirm proper installation and alignment of tires on the wheels.
3. Record tire maintenance activities in the aircraft logbook, including tire pressure,
rotation, and any observed issues.
 Other Service Items Checklist
Pre-Service Preparation:
1. Review the maintenance manual for the aircraft to determine specific service
intervals and procedures for each item.
2. Gather necessary tools, equipment, and materials required for servicing.

Oleo Struts:
1. Check oleo struts for loss of air or fluid as per maintenance manual guidelines.
2. Service oleo struts as needed based on inspection findings.
3. Perform major reconditioning or overhaul when necessary.

Shimmy Dampers:
1. Inspect shimmy dampers for leaks or damage.
2. Service or replace shimmy dampers according to maintenance manual instructions.

Bungee Cylinders:
1. Check bungee cylinders for wear and tear.
2. Service or replace bungee cylinders as required by maintenance manual guidelines.
 Other Service Items Checklist
Instrument Filters:
1. Inspect instrument filters for debris or blockages.
2. Clean or replace instrument filters according to maintenance manual
recommendations.

Fuel Screens:
1. Check fuel screens for contamination or clogging.
2. Clean or replace fuel screens as specified in the maintenance manual.

Heaters:
1. Inspect heaters for proper functioning.
2. Service or repair heaters as necessary to ensure optimal performance.
 Other Service Items Checklist
Other Parts:
1. Identify any additional parts requiring service as per maintenance manual
instructions.
2. Follow specific maintenance procedures for each item listed in the manual.

Post-Service Verification:
1. Double-check all serviced items for proper operation and functionality.
2. Ensure that all maintenance tasks have been documented accurately in the aircraft
logbook.
3. Record any parts replaced or serviced, along with the date and details of the service
performed.
END