The Saturn AL-31 is a family of military turbofan engines. It was developed by Lyulka, now NPO Saturn, of Russia (former Soviet Union), originally for the SukhoiSu-27 'Flanker' air superiority fighter. It produces a total thrust of 123 kN (27,600 lb) with afterburning in the AL-31F, 137 kN (30,800 lb) in the AL-31FM (AL-35F) and 142 kN (32,000 lb) in the AL-37FU variants. Currently it powers all Flanker derivatives and the Chengdu J-10 multirole jet fighter which has been developed in China.
AL-31FP and AL-37FU variants have thrust vectoring. The former is used in the Su-30MKI export version of the Flanker for India and the latter, in the Su-37 and Su-47 Berkut prototypes. The AL-37FU can deflect its nozzle to a maximum of ±15° at a rate of 30°/sec. The vectoring nozzle is utilized primarily in the pitch plane.
It has a reputation for having a tremendous tolerance to severely disturbed air flow. In the twin-engined Flanker, the engines are interchangeable between left and right. The Mean Time Between Overhaul (MTBO) for the AL-31F is given at 1000 hours with a full-life span of 3000 hours. Some reports suggested that Russia was offering AL-31F to Iran to re-engine its F-14 Tomcat air fleet in the late 1990s.
The 117S is a major upgrade of the AL-31F intended to power the Su-35BM, producing 142 kN (32,000 lb) of thrust in afterburner and 86.3 kN (19,400 lb) dry. It features a fan 3% larger in diameter (932 mm versus 905 mm), advanced high- and low-pressure turbines, an all-new digital control system, and provisions for thrust-vectoring nozzles similar to the AL-31FP. This engine will have an assigned life of 4,000 hours and an MTBO of 1,000 hours.1 The first flight of this engine was completed in an Su-35BM on 20 February 2008.2
