STC approved for 5-blade props on PC-12s

June 7, 2010

5-blade props on PC-12sFinnoff Aviation of Boulder, Colo., has developed an FAA- and EASA-approved supplemental type certificate (STC) that lets Pilatus PC-12 owners install five-blade composite propellers on their airplanes.

The propeller, built by MT-Propeller of Atting, Germany, weighs 10 pounds less and has one more blade than stock PC-12 props, 1.75 inches more ground clearance, and yields performance advantages, Finnoff says. Among them are a 15-percent reduction in takeoff ground run, a 15-percent greater climb rate, a five-knot boost in cruise speed, and nearly vibration-free operations.

The new propeller’s resonance is such that the usual vibrations attending engine operations at startup, flight idle, and shutdown are greatly reduced. Noise levels are also diminished. MT-Propeller claims that cabin noise levels are cut by six to seven dB(A) and that aircraft noise level is reduced by four dB(A) compared to the standard metal propeller.

The price is $56,600, with the exchange of the original propeller. The STC includes a new hub and a newly-designed, stainless steel spinner ring to send electrical power to the blades’ ice protection boots. No engine modifications are required for installation. Current TBO is set at 2,000 hours or 72 months, whichever comes first. Target TBO is 3,000 hours.