Maintenance, Airworthiness and Defect Reporting
What this domain tests
This section tests how defects are reported, how airworthiness is maintained, and what records and inspections apply to turbine aeroplanes.
Core rules
- Defects must be recorded in the maintenance log or approved system with enough detail to reproduce the problem: phase of flight, altitude, OAT, N1/N2, EGT, fuel flow and duration.
- The MEL (minimum equipment list) allows some items to be deferred with conditions; it does not allow a known unsafe condition.
- Maintenance includes borescope inspection, oil analysis, trend monitoring, airworthiness directives and service bulletins. Airworthiness directives are mandatory.
- After an exceedance, maintenance assesses damage before further flight.
Worked example
A pilot writes: 'At FL350, OAT −50°C, N1 88%, EGT 910°C (limit 900°C) for 5 seconds during climb; engine returned to normal; no vibration.' Reasoning: this gives maintenance the data to decide whether a borescope is needed. A vague report such as 'EGT high' forces guesswork and delays rectification.
Traps
- Deferring a defect without checking the MEL conditions.
- Writing a defect without numbers or phase of flight.
- Assuming an airworthiness directive applies only to the airframe; engine directives exist too.
- Signing off a task without the required documentation.
Key points
- Defect reports need numbers: phase, altitude, OAT, N1/N2, EGT and duration.
- The MEL allows deferral only when its conditions are met.
- Airworthiness directives are mandatory; service bulletins are usually recommended.
- Borescope, oil analysis and trend monitoring support airworthiness.
- After an exceedance, maintenance assesses before further flight.