Powerplant — PT6A-68
Free-turbine reverse-flow turboprop. Gas generator section aft (4-axial + 1-centrifugal compressor, 1-stage CT), power section forward (2-stage PT, 2-stage planetary reduction gearbox to 2,000 RPM prop). Flat-rated 1,100 SHP installed in the T-6.
- ▸PCL is electrical primary (to PMU) + mechanical backup (to FMU). Idle gate stop must be lifted to reach CUT-OFF.
- ▸PMU = single-channel electronic engine control. Powered by PMA on the RGB; reverts to 28 VDC battery bus below 40–50% Np.
- ▸Ground vs flight idle: WOW-controlled. Ground idle 60% Ng; flight idle ~67% Ng. Above 10,000 ft PA, PMU raises Ng to keep Np > 80% in spins.
- ▸PMU auto-aborts start if ITT > 940 °C / 2s, > 870 °C / 4s, > 840 °C / 19s; or Ng accel < 50% normal; or no light-off within 10 s.
- ▸PMU OFF (manual): mechanical flyweight governor caps Np at 100 ±2%. Expect torque surge from low to governed RPM.
- ▸Oil system 18.5 US qt. Two pickup elements (one for inverted flight up to 15 s). Cooler in lower aft cowl.
Key Limits
- Inverted flight
- 15 s max
- Intentional 0-G
- 5 s max
- Start ITT (momentary)
- 1,000 °C
- Transient ITT
- 870 °C ≤ 20 s
- Starter duty (1st)
- 20 s on / 30 s cool