Allison T56

T56 / Model 501
A T56 mounted on a U.S. Air Force C-130 Hercules receives maintenance.
TypeTurboprop
National originUnited States
Manufacturer
Major applications
Number built>18,000
Developed fromAllison T38
Developed intoRolls-Royce T406

The Allison T56 is an American single-shaft, modular design military turboprop with a 14-stage axial flow compressor driven by a four-stage turbine. It was originally developed by the Allison Engine Company for the Lockheed C-130 Hercules transport entering production in 1954. It has been a Rolls-Royce product since 1995 when Allison was acquired by Rolls-Royce. The commercial version is designated 501-D. Over 18,000 engines have been produced since 1954, logging over 200 million flying hours.