Maintenance Practices, Safety and Airworthiness Requirements
Maintenance Practices, Safety and Airworthiness Requirements tests the rules that keep a turbine helicopter legally and physically airworthy. In the NZ system, maintenance must be performed and certified under the applicable CAA rules, with approved data and recorded in the appropriate maintenance records.
Core rules
- Maintenance includes inspection, repair, overhaul, modification and testing; it must be carried out by authorised persons and certified.
- Use approved data: maintenance manuals, service bulletins, airworthiness directives and approved modifications.
- Life-limited parts must be tracked by hours or cycles and removed before limit.
- Calibrated torque wrenches, correct lockwire, correct fasteners and FOD control are basic airworthiness requirements.
- Independent inspections and dual checks apply to critical assemblies such as flight controls, rotor drive and engine installation.
- Safety: isolate ignition and fuel, discharge static, use PPE, and control flammable liquids.
Worked example
A life-limited main rotor gearbox part has a limit of 1500 hours and 1480 hours are recorded. The next planned flight is 1.5 hours. Remaining life is 20 hours, so the flight would leave 18.5 hours, which is legal if no other limit applies. But if the part also has a calendar limit or an airworthiness directive requires replacement at 1490 hours, the part must be removed before flight. Always check all limits, not just the one you remember.
Traps
- Signing off work without the correct certification.
- Fitting an unapproved part because it looks the same.
- Mixing hours and cycles.
- Skipping an airworthiness directive because it is only a bulletin.
- Returning an engine to service with an unresolved exceedance.