How long does a airplane last?

Answer 1

Like cars, it entirely depends on how well they are looked after and how tough their working lives are. On average, the lifespan of the average aircraft is considerably longer than that of your average car.

The average lifespan of a commercial passenger jet is 25 to 30 years.

The Manufacturer establishes a life span for the airframe. During certification of the airplane, one is built that is tested in a test fixture that simulates take-off and landings. It applies loads to the wings and tail and sometimes they apply internal pressure to the fuselage to represent the air pressing on the skin. They test the aircraft through flight cycles that represent 4 times the expected life of the aircraft. So if they want the plane to fly 90,000 cycles, they apply 360,000 cycles. This ensures sufficient safety factor in their prediction.

In the 1980's Bell Helicopter realized that they became concerned about the age of some of their helicopters. Some people were re-building the helicopters and continuing to fly them with the same ID Plate. This was a liability to Bell; if the airplane crashed they could be sued. So they placed a 20 year life on their helicopters, meaning after that time the helicopter had to be destroyed along with the data plate.

Also, some major structural components of airplanes are also tested to determine a life. This includes Engines, Landing Gear and major Structural fittings. This life is called the Safe Life Limit and is based upon fatigue testing and analysis. A landing gear is tested until it fails. The data is used to predict the time(or cycles) to failure for the loads it would see on an airplane. Then this calculated life cycles is reduced by 1/3 or less and this is the Safe Life Limit. When the part accumulates that many cycles, then it is destroyed. That doesn't mean it will have a fatigue crack in the part. It only means that the part has had repeated fatigue loads applied and that 99.7% of the parts would not fail if it was removed from service.