The Learjet Model 35 and Model 36 are a series of American multi-role business jets and military transport aircraft manufactured by Learjet between 1973 and 1993. When used by the United States Air Force, they carry the designation C-21A. Learjet was acquired by Bombardier Aviation in 1990 and is now a subsidiary, so the aircraft is also known as the Bombardier Learjet 35.

The Garrett TFE731 is a family of geared turbofan engines commonly used on business jet aircraft. Garrett AiResearch originally designed and built the engine, which due to mergers was later produced by AlliedSignal and now Honeywell Aerospace.