 The aircraft is powered by two DEEC-controlled Honeywell TFE731-20-AR turbofan engines, rated at 3,500 pounds thrust, each, in sea-level temperatures up to 88 °F – a fuel-efficient, "understressed," derated version of the 4,435 lb thrust TFE731-40 – developed specifically for the Learjet 45.Recommended engine TBO (Time Between Overhauls) is 5,000 hours.At normal atmospheric conditions, zero-wind takeoff runway requirements range from 4,200 feet (for a stripped, basic plane with a basic operating weight of 11,700 pounds) to 5,040 feet for a fully equipped model, with auxiliary power unit and other upgrades (14,200 lbs).