Gyroplane Systems and Rotorcraft Maintenance
Systems and maintenance questions cover the rotor head and blades, the prerotator, the engine and propeller, and the inspection rules that keep a gyroplane legal. Because many gyroplanes are experimental amateur-built, you must know both standard and experimental requirements.
Rotor system
- The mast carries the rotor head; the teeter bolt and hub bar allow the blades to see-saw, or flap, as they advance and retreat.
- The prerotator spins the rotor before takeoff; the rotor brake stops it after landing. Neither is a flight control.
- Trim systems relieve cyclic pressure; some machines use pneumatic or electric trim.
- Inspect blades for cracks, delamination, leading-edge erosion, and loose hub hardware; check teeter bolt torque and bearing play on the manufacturer's schedule.
Powerplant and propeller
- Engine, reduction drive or gearbox, and propeller; monitor oil temperature and pressure, cylinder head temperature, and exhaust condition.
- Rotor tachometer and engine tachometer are separate instruments; know both limits.
- Fuel system: tanks, selector, filter, and primer; check for contamination at every preflight.
Inspection and records
- Standard-category aircraft need an annual inspection every 12 calendar months under 91.409 and compliance with all ADs.
- Experimental aircraft operate under their operating limitations and need a condition inspection every 12 calendar months by an appropriately rated person.
- Records under 91.417 must show inspections, repairs, and AD compliance; the aircraft must carry its airworthiness certificate, registration, and operating limitations.
Worked example
During preflight a pilot finds the rotor tachometer reading zero while the engine tach works. Rotor RPM is what takeoff depends on, so the correct action is to cancel the flight and troubleshoot the sender or gauge rather than eyeball rotor speed.
Traps
Confusing engine RPM with rotor RPM; skipping teeter bolt torque checks; flying an experimental gyroplane with an expired condition inspection; and assuming automotive maintenance practices apply to aircraft hardware.