The lifecycle of a plane
When it comes to the lifespan of a plane, it can seem confusing that some newer models are retired after just a few years, whilst classic ones are still able to take to the skies. That’s because planes don’t age like we do, it’s not about how many hours they fly, but how often.
An aircraft's age is determined by pressurisation cycles, as each time it takes off, or lands the fuselage and wings go through immense stress. Both are made from large pieces of metal which are fastened and riveted together, so cracks can start to develop around them as the metal fatigues. So, it’s the aircraft doing the short hops all day, every day that have the shortest lives as they are going through the most pressurisation cycles.
Because of this, manufacturers have strict maintenance programmes to ensure any fatigue is caught well before it could cause a problem. Aircraft are trouble-free for a certain amount of cycles, but from then on they must be regularly tested and parts inspected and replaced when needed. Inspections take place during the production of the components and then frequently throughout their lifespan, but these can be timely and costly. To help speed up this process a technique involving ultrasonic phased-array testing which uses ultrasonic waves with varying time delays to look at and inside the material are used to help find and analyse any defects.
When planes have come to the end of their lifespan they are taken to specialists to be dismantled, with the engines removed first, followed by the interiors which can be repurposed on board another aircraft. After everything from the seats to the cockpit controls have been removed, the aircraft itself is chopped up and recycled.