In many aviation online communities I see many of the same fundamental question: why did this one type of airliner outlast newer ones? Why did they get rid of this one type? When are they finally going to retire this plane? And so on. The reasons why some planes get sent sooner than others depend on the airline itself, why it got that type in the first place and whether or not that justification or reasoning still exists. Regardless of why or when, all airliners share the same fate: sooner or later, they’ll get to the Boneyard eventually.
Aluminum has a certain “shelf life” (or fatigue life, to use the technically correct term) where it can take a theoretically fixed amount of abuse before it fails, and depending on the nature of that use that can occur quickly. The general rule of thumb is that airliners (especially large and particularly sturdy ones like the 747) can last up to 100,000 flight hours or 100,000 cycles. What’s the difference? Flight hours is exactly what it sounds like – the total amount of time the aircraft is in the air (well, not quite, but for our purposes we’ll stick to this simplistic definition). A cycle represents one trip of the aircraft from Airport A to Airport B, or more specifically for our purposes, the time the pressurization system is activated on the ground to the time it’s de-activated on the ground at the destination airport. Flying puts a lot of stress on an aluminum tube – turbulence for one, but also the simple act of moving through the air. Wings bend – actually, they bend a lot as part of how the aircraft defeats turbulence for the sake of passenger comfort and achieve high fuel efficiency. Things bend and move imperceptibly as flight attendants move about the aircraft, systems function within their normal parameters, and in just experiencing the act of existing as a component of a large moving machine. These are small, tiny forces, but after 20 years of flying across the Pacific Ocean for half a day each flight, they add up. … Continue at http://oppositelock.jalopnik.com/why-airliners-get-sent-to-the-boneyard-1614890215…
Photo: (c) Alan Radecki via Wikipedia
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