The Garrett AiResearch TPE331 is a turboprop engine originally designed and manufactured by Garrett AiResearch, and produced by Honeywell Aerospace since 1999 after that company acquired Garrett. The TPE331 family includes 18 models and 106 configurations; the engines range from 575 to 1650 shaft horsepower. The military version is designated the T76.
The TPE331 originated in 1961 as a gas turbine (the "331") to power helicopters. It first went into production in 1963. More than 700 had been shipped by the end of 1973. It was designed to be both a turboshaft (TSE331) and a turboprop (TPE331), but the turboshaft version never went into production; however, over 14,000 TPE331s have been sold since the first engine was produced in 1963, installed on the Aero Commander in 1964 and put into production on the Aero Commander Turbo Commander in June 1965.