Honeywell’s business aviation segment recently celebrated the 40th anniversary of the TPE331 turboprop at its Phoenix Sky Harbor International Airport facility. Since the first of the line entered service in 1965 on the military OV-10 Bronco, the TPE331, along with the TFE731 turbofan, has been a mainstay of the Garrett/AlliedSignal/ Honeywell engine business.

Of the more than 13,000 TPE331s delivered to date, some 12,000 remain in operation, offering between 500 and 1,500 shp. No fewer than 180 separate dash numbers have powered executive aircraft such as the Turbo Commander series and Mitsubishi MU-2, numerous regional airliners and most recently the General Atomics Predator B unmanned aerial vehicle (UAV).

In addition, more than 1,300 copies of the TPE331-10 engine have gone into upgrades and conversions of prop-driven aircraft, notably the Grumman S-2F Tracker submarine hunter, which has been reborn as a firefighting aerial tanker for the California Department of Forestry.

Honeywell introduced and presented awards to several of the engine’s original designers and production engineers, now retired, who collaborated in Garrett’s development of a propulsion turboprop from an auxiliary power unit engine core and organized a worldwide TPE331 product support network.

Then Rear Adm. Thomas Cassidy, USN (Ret.), president of General Atomics’ Aeronautical Systems in San Diego, related how talks six years ago led to development of a TPE331 version that powers the Predator B. Twelve of those UAVs are in service, with more on order for the U.S. Air Force and Navy, border patrol
and homeland security as well as the UK, Australia, Canada and Italy.

Admiral Cassidy said the Predator B, which carries a wide variety of sensors, can remain airborne for up to 30 hours, making it effective in civil roles such as fisheries monitoring, pinpointing and measuring wildfire hotspots, and utility line patrol. He added that Aeronautical Systems is considering building a more powerful UAV, a Predator C, with more extensive capabilities.