How long are aircraft jet engines built to last?

Modern commercial jet engines are designed to last decades with proper maintenance. Military engines have relatively shorter lifespans due to accelerated loads during high-performance missions.

aircraft maintenance MRO

Modern jet engines used on commercial aircraft are built with a lifecycle of 25 to 35 years, depending on use and maintenance routines. A typical jet engine lasts 25,000 to 45,000 flight cycles or approximately 150,000 flight hours with proper maintenance.

The life of a commercial jet engine is considerably longer than that of an average automobile, which lasts approximately 150K – 200K miles. Assuming an average run of 15,000 miles a year, a car engine may last 10-15 years.

Jet engines designed for military aircraft have very different performance parameters, and their lifecycle is generally based on mission hours. Military engines have a much shorter life than their commercial counterparts, in the range of 5,000 to 10,000 mission hours. The F-135 turbofan engine powering the Lockheed Martin F-35 Lightning aircraft is designed to last 8,000 hours.

Engine Category Type Aircraft Lifespan
CFM56-7 Commercial Narrowbody Boeing 737 NG 35,000 cycles
GE90-115B Commercial Widebody Boeing 777 25,000 cycles
PW-1000G Commercial Narrowbody Airbus A320neo, A220 40,000 cycles
F-135 Military F-35 Lightning II 8,000 hours
F110-GE-129 Military F-16 Fighting Falcon 6,000 hours
RD-33 Military MiG-29 3,000 hours

Engine flight cycles and flight hours

An engine flight cycle (EFC) is an engine startup to shutdown routine, including run-up to operating temperatures. High-trust operations cause stress and fatigue on internal parts of the engine. The EFC measures thermal stresses on engine components.

EFC is not to be confused with aircraft flight cycles (AFC), which comprises pressurisation and depressurisation of the cabin (takeoff and landing). The AFC is a measure of structural fatigue on the airframe. For example, a “touch and go” landing is generally considered part of the same AFC but can be recorded as an additional EFC, particularly when the engine power is idle and then increased for takeoff and climb.

Similarly, if an engine is started and shut down without taking off, it may incur an EFC but not an AFC. Nonetheless, it is common for airlines to record EFC and AFC as a single measure, particularly during normal flight operations.

F-100 engine on test
Photo: Shelley Gill / Wikimedia Commons

An engine flight hour (EFH) is a measure of the time an engine is running, irrespective of the phase of flight. An engine installed on a narrowbody aircraft may accumulate 4 to 6 cycles in a day, whereas a widebody engine may record 1-2 cycles a day. As such, the engine life is measured by EFCs rather than just EFHs, as the stresses during takeoff and landing are more intense than steady cruise flight.

Performance and maintenance of jet engines

The performance of a jet engine is measured through the internal temperature and overall pressure ratio of the engine. The engine’s exhaust gas temperature (EGT) measured in the turbine section determines its operational performance. Similarly, the pressure ratio between the high-pressure (HP) compressor inlet and exit determines the engine’s efficiency. 

A jet engine can undergo multiple overhauls, typically every few thousand cycles, before retirement. During the maintenance shop visit, the engine is removed, dismantled, and rebuilt to extend its service life. An aircraft usually runs through 2-3 sets of engines during its lifetime.

Aircraft Maintenance and MRO turnaround time consistency will make companies more competitive
Photo: stock.adobe.com

Essentially, commercial jet engines are designed for endurance, lasting decades with proper maintenance. Military engines, on the other hand, are designed for performance, leading to more frequent overhauls and relatively shorter lifespans.

Featured image: aapsky / stock.adobe.com

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