TPE331
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Technical Specifications
- Dry Weight
- 155 kg
- Length
- 1.120 m
- First Run
- 1961
- In Service
- 1965
Honeywell TPE331
The TPE331 is one of the most prolifically produced small turboprop engines in aviation history, with over 13,000 units delivered since entering service in 1965. Developed originally by Garrett AiResearch (later AlliedSignal, now Honeywell), it covers a power range of 575 to 1,100 shaft horsepower (SHP) across numerous variants. Its compact dimensions, robustness, and single-shaft simplicity made it the preferred choice for a generation of utility and commuter aircraft including the Dornier 228, Fairchild Merlin and Metro, Mitsubishi MU-2, and Thrush agricultural aircraft.
Technical Specifications
| Parameter | Value |
|---|---|
| Shaft Horsepower | 575–1,100 SHP (variant-dependent) |
| Dry Weight | 155 kg (342 lb) |
| Length | 1.120 m (44.09 in) |
| First Run | 1961 |
| Entry into Service | 1965 |
| Units Delivered | 13,000+ |
| Status | In Production |
Design Characteristics
The TPE331's most distinctive design feature is its reverse-flow, single-shaft architecture. Unlike most turboprops where air flows straight through from front to back, the TPE331 routes compressed air backward through a reverse-flow combustion chamber before passing forward through the turbine. This arrangement shortens the overall engine length significantly, making it well-suited to single-engine and light twin installations where nacelle space is constrained.
As a single-shaft design, the compressor, turbine, and propeller gearbox are all mechanically linked, running at a fixed speed ratio. This simplifies the design and reduces parts count compared to free-turbine engines but means the propeller rpm is tied to the gas generator speed, requiring careful propeller design for efficient operation across the power range.
Applications and Legacy
The TPE331 found its natural market in utility turboprops operating in remote and demanding environments. The Dornier 228 STOL utility aircraft, widely used for remote island and polar operations, relies on the TPE331 for the combination of power density and short-field performance its missions demand. The Fairchild Metro and Merlin commuter airliners brought the engine into scheduled passenger service throughout the 1970s and 1980s.
The agricultural aviation sector has also been a significant market: the TPE331 powers the Thrush family of crop dusters, where its durability in low-altitude, dusty environments and resistance to chemical contamination are valued above all else. With production continuing and a vast installed base requiring support, the TPE331 will remain a fixture in utility aviation for decades to come.