The Honeywell TPE331 (military designation: T76) is a turboprop engine. It was designed in the 1950s by Garrett AiResearch, and produced since 1999 by its successor Honeywell Aerospace. The engine's power output ranges from .
Garrett AiResearch designed the TPE331 from scratch in 1959 for the military. "Designed as a 575-horsepower engine it was not a scaled-down version of a larger engine, as competitors were offering." 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. 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.
The 715 shp TPE331-6 used in the Beechcraft King Air B100 has a 400 hr fuel nozzle cleaning interval, 1,800 hr hot section inspection interval, and a 5,400 hr. time between overhaul; approval is possible for 3,000 hr HSIs and 6,000 hr overhauls, and engine reserves are cheaper than for the PT6A.