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Aero-Tips 11.19.06

Many airplane owners like to keep the cost of ownership down by doing some routine maintenance tasks themselves. Some people find that it's fun to do some work on the airplane. What's legal, and what special requirements exist for do-it-yourself work?

Maintenance, not repair

Only certificated mechanics are allowed to sign off on repairs to an airplane. Anyone can perform any maintenance or repair to an airplane so long as the work is observed, inspected and endorsed by a mechanic. But there are a number of "preventative" maintenance tasks that owners are permitted to do without mechanic oversight.

Part 43 Appendix A

(c) Preventive maintenance. Preventive maintenance is limited to the following, provided it does not involve complex assembly operations:

• Removal, installation, and repair of landing gear tires.
• Replacing elastic shock absorber cords on landing gear.
• Servicing landing gear shock struts by adding oil, air, or both.
• Servicing landing gear wheel bearings, such as cleaning and greasing.
• Replacing defective safety wiring or cotter keys.
• Lubrication not requiring disassembly other than removal of nonstructural items such as cover plates, cowlings, and fairings.
• Making simple fabric patches not requiring rib stitching or the removal of structural parts or control surfaces.
• Replenishing hydraulic fluid in the hydraulic reservoir.
• Refinishing decorative coating of fuselage, wings tail group surfaces (excluding balanced control surfaces), fairings, cowlings, landing gear, cabin, or cockpit interior when removal or disassembly of any primary structure or operating system is not required.
• Applying preservative or protective material to components where no disassembly of any primary structure or operating system is involved and where such coating is not prohibited or is not contrary to good practices.
• Repairing upholstery and decorative furnishings of the interiors when it does not require disassembly of any primary structure or operating system or interfere with an operating system or affect the primary structure of the aircraft.
• Making small simple repairs to fairings, nonstructural cover plates, cowlings, and small patches and reinforcements not changing the contour so as to interfere with proper air flow.
• Replacing side windows where that work does not interfere with the structure or any operating system such as controls, electrical equipment, etc.
• Replacing safety belts.
• Replacing seats or seat parts with replacement parts approved for the aircraft, not involving disassembly of any primary structure or operating system.
• Trouble shooting and repairing broken circuits in landing light wiring circuits.
• Replacing bulbs, reflectors, and lenses of position and landing lights.
• Replacing wheels and skis where no weight and balance computation is involved.
• Replacing any cowling not requiring removal of the propeller or disconnection of flight controls.
• Replacing or cleaning spark plugs and setting of spark plug gap clearance.
• Replacing any hose connection except hydraulic connections.
• Replacing prefabricated fuel lines.
• Cleaning or replacing fuel and oil strainers or filter elements.
• Replacing and servicing batteries.
• Replacement or adjustment of nonstructural standard fasteners incidental to operations.
• The installations of anti-misfueling devices to reduce the diameter of fuel tank filler openings provided the specific device has been made a part of the aircraft type certificate data by the aircraft manufacturer, the aircraft manufacturer has provided FAA-approved instructions for installation of the specific device, and installation does not involve the disassembly of the existing tank filler opening.
• Removing, checking, and replacing magnetic chip detectors.
• Removing and replacing self-contained, front instrument panel-mounted navigation and communication devices that employ tray-mounted connectors that connect the unit when the unit is installed into the instrument panel, (excluding automatic flight control systems, transponders, and microwave frequency distance measuring equipment (DME)). The approved unit must be designed to be readily and repeatedly removed and replaced, and pertinent instructions must be provided. Prior to the unit's intended use, and operational check must be performed in accordance with the applicable sections of part 91 of this chapter.
• Updating navigational software data bases (excluding those of automatic flight control systems, transponders, and DME) provided no disassembly of the unit is required and pertinent instructions are provided. Prior to the unit's intended use, an operational check must be performed in accordance with applicable sections of part 91 of this chapter.
• There are additional items for balloons and primary category aircraft.

Owners only

Notice that the Part 43 Appendix A items can be performed only by airplane owners. If you rent or borrow the airplane and are not a mechanic you can't do the work without a mechanic's final endorsement. Note also that just because you own the airplane, you're qualified to do the work -- spend some time with a mechanic to learn how to do each task before you try it yourself (and be sure to properly compensate the mechanic for the tutelage).

Aero-tip of the day: Save money, have fun, and learn more about your airplane by doing owner-performed maintenance.

FMI: Aero-Tips