To answer what seems to be a relatively simple question, it is essential to understand the factors that define the life of an airliner and a jet engine. Airliners and jet engines are complex machines whose lifespan is difficult to determine in absolute flight cycles, flight hours, or operational years. Like any other machine, the manufacturers build them with a specific design limit. However, the actual lifespan depends on usage, operating conditions, and maintenance. Before getting into the specifics, here is a brief look into the lifespan of airliners and engines.
The typical lifespan of airliners
Short-range narrowbody jets have an intended lifespan of nearly 50,000 flight cycles. On average, an Airbus A320 operates four flights a day and can last almost 35 years of operation, plus maintenance downtime. On the other hand, a long-range widebody jet’s life varies between 25,000 and 45,000 flight cycles, depending on the structure. The composite-driven Boeing 787 Dreamliner is designed for 44,000 flight cycles. These jets can theoretically last several decades with an average of two flight cycles a day.
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Unlike commercial airliners, fighter jets are unique due to their mission requirements. These jets are exposed to extreme operating conditions such as speed, altitude, maneuverability, and G loads. A typical fighter jet has an active life of 5,000 to 8,000 flight hours. With an average of 20 flight hours a month, fighter jets can last well over 30 years, plus maintenance downtime.
The typical lifespan of jet engines
While some jet engines are solely designed for a specific aircraft type, others may be used across a wide range of commercial and military aircraft. During their lifetime, jet engines undergo 2-3 complete overhaul cycles. During one or more overhaul visits, engine parts are either repaired or replaced. With very high operating temperatures in the hot section, the time-on-wing significantly reduces in subsequent shop visits.
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The average number of cycles before the first overhaul for modern narrowbody engines is 12,000 flight cycles. For the two subsequent maintenance visits, the number of cycles may be reduced to 8,000 and 4,000, respectively. With an overhaul costing several million dollars, further shop visits could not be economically viable for operators. The average number of hours before the first overhaul for modern widebody engines is 20,000 flight hours. Subsequent maintenance visits reduce this number to as low as 5,000 flight hours.
Photo: Vincenzo Pace | Simple Flying
In the end-of-life phase, it is common for jet engines to be installed on smaller type-variants to be operated at lower thrust levels. Engines on a fighter aircraft typically last between 3,000 and 6,000 flight hours.
So, how many engines should an airliner need during its lifespan?
It is not uncommon for commercial airliners to go through 3-4 sets of engines during their lifetime. Operators that use multiple variants of the same aircraft type tend to rotate the engines based on economic viability. Operators of military aircraft such as the Lockheed Martin C-130 Hercules and Boeing C-17 Globemaster usually acquire multiple spares, which can be rotated more frequently than on commercial aircraft. Fighter jets may utilize up to two sets of engines during their operational lifespan.
What do you think about the number of engines airliners typically acquire during their lifetime? Tell us in the comments section.
Source: simpleflying.com
