Maintenance Practices
Domain 10 - Maintenance Practices
The exam tests approved data, torque and safetying, FOD control and configuration control.
Core rules
- Approved data includes the AMM, IPC, SRM, TSM, airworthiness directives and service bulletins. A part is airworthy only if it is approved, traceable and correctly certified; a part that looks the same is not automatically acceptable.
- Torque: use calibrated tools within their specified range, torque in the specified sequence, and account for lubrication and thread condition. Over-torque damages threads and preload.
- Safetying: lockwire with correct double-twist and direction, cotter pins, one-use self-locking nuts and torque seal.
- FOD control: caps and plugs, tool control and inspection before closing. Preserve engines for storage and after washing.
- Borescope inspections are scheduled and also follow FOD, bird strike or over-temperature events; findings are recorded against manual limits.
- Configuration control: effectivity by engine serial number, modification status and software version.
Worked example
A technician fits a serviceable-looking fuel nozzle taken from another engine. The type is correct but there is no authorised release document or traceability record. The correct action is to quarantine the part, not fit it. An untraceable part is unairworthy even if it would function; the finding is traceability, not function.
Traps
- Using a torque wrench at the bottom of its scale for a small fastener.
- Reusing a self-locking nut or a cotter pin.
- Signing off a borescope without recording blade location and the limit reference.