Aeroplane Systems - Flight Controls, Landing Gear and Cabin
Flight controls
Primary controls are aileron, elevator and rudder; secondary are flaps, slats, spoilers and trim. Cable systems use turnbuckles, fairleads and pulleys, with tension checked against the manual at a stated temperature and re-checked after rigging. Control surfaces are mass-balanced: painting or repairing a surface shifts its balance and can allow flutter, so rebalance per the manual. Control locks must be removed and recorded; after any connection, an independent inspection and full-range movement check are required. Fly-by-wire systems need rigging and built-in test per the AMM.
Landing gear and brakes
Oleo struts contain oil and dry nitrogen and are serviced to a specified extension, usually with the aircraft on jacks. Check torque links, shimmy damper, steering, retraction locks and downlock springs. Brakes need the correct fluid, correct bleeding, and disc wear checked against wear pins or limits; tyres have wear and pressure limits. Anti-skid systems need wheel speed sensor checks.
Cabin
Pressurisation uses an outflow valve and controller, with positive-pressure and negative-pressure relief valves; door seals and pressure hull penetrations matter. Cabin oxygen, emergency equipment and restraint condition are part of the inspection.
Worked example
Nose wheel shimmy after landing. Shimmy is a dynamic oscillation: check tyre pressure and wear, wheel balance, play in torque links and steering, and damper condition. A tight damper alone will not cure shimmy caused by an under-inflated tyre.
Traps
Using oxygen in a strut; ignoring mass balance after paint; measuring strut extension on the wheels when the manual says jacks; using the wrong brake fluid.