15.21 and 15.22 Engine monitoring, ground operation, storage and preservation

Scope

• 15.21 Engine monitoring and ground operation — A level 1, B1 level 3 (the only level-3 item in Module 15): starting and ground run-up procedures; interpretation of power output and parameters; trend monitoring (oil analysis, vibration, borescope); inspection to manufacturer's criteria; compressor washing; FOD.
• 15.22 Engine storage and preservation — B1 only, level 2: preservation and depreservation of engine, accessories and systems.

Ground running — safety first

• Only authorised, trained personnel run engines; aircraft positioned in an approved run-up area facing into wind, chocked, brakes set, tied down for high-power runs where required.
• Danger areas: the intake suction zone (people can be ingested — distances increase greatly with power) and the exhaust zone (heat and blast, hundreds of metres at take-off power). Beacon on, observer/fire guard in communication with the flight deck, fire extinguisher available.
• FOD walk before running; cowlings secured; check intake and exhaust clear.
• Communication: headset contact with ground crew, standard hand signals.

Starting and run-up procedure (typical)

1. Pre-start checks: fuel, oil quantity, hydraulic, electrical/APU or ground air supply, fire test, beacon on.
2. Start sequence (see 15.13) — watch for light-off within the time limit, EGT (hot start), N2 acceleration (hung start), oil pressure rising, N1 rotation.
3. Warm-up at idle; check stabilised idle values against limits/charts.
4. Power checks as required by the task: acceleration/deceleration times, take-off power assurance (EPR/N1 achieved against EGT and N2 for the day's ambient conditions using correction charts), vibration levels, bleed and anti-ice valve operation, thrust-reverser function, generator loading.
5. Cool-down period at idle before shutdown (thermal stabilisation — avoids rubs and bowed rotors).
6. Shutdown — note run-down time (abnormally short → rubbing/bearing problem), check for afterfire and leaks.