Aircraft Maintenance Practices and Safety
This domain covers ground handling, servicing, and the safety discipline that prevents injury and aircraft damage. The exam favours scenarios: what do you connect first, which extinguisher, what do you do before jacking.
Ground handling and servicing
- Ground and bond the aircraft before fueling. Connect the bonding cable to the aircraft first, then to the fuel source, and keep the nozzle in contact with the filler neck.
- Use only approved oxygen equipment; no oil, grease or hydraulic fluid near oxygen fittings.
- Jack only at approved points, with the aircraft correctly ballasted and the jacking load within limits. Install safety locks or stands before working under the aircraft.
- Towing requires a qualified driver, wing walkers, and a tow bar rated for the aircraft; never turn the nose gear beyond its steering limits.
- Control FOD: tool control, inventory, and clean-as-you-go.
Fire and hazardous materials
Class A fires involve ordinary combustibles, Class B flammable liquids, Class C energized electrical equipment, and Class D combustible metals such as magnesium. Water spreads fuel fires; use foam, CO2 or dry chemical on Class B. Read the safety data sheet before handling hydraulic fluid, Skydrol, solvents or paint.
Worked example
A mechanic is about to service an oxygen system but the wrench was previously used on a hydraulic line and is oily. Oxygen under pressure combined with hydrocarbon contamination can ignite. The correct action is to stop, use oxygen-clean equipment, and never use the contaminated wrench.
Traps that cost marks
- Bonding the fuel truck before the aircraft.
- Using water on a fuel fire or CO2 on a magnesium wheel fire.
- Jacking without checking the CG or installing safety stands.
- Skipping lockout/tagout before working on a moving surface.