Watewate From Canada, joined Nov 2000, 2284 posts, RR: 1
Reply 1, posted (13 years 2 months 4 days 22 hours ago) and read 755 times:
Age of an a/c is not true indicator of its use. Number of cycles is the most logical measuring stick for airlines do decide whether the a/c will stay or go. Other considerations, such as age (obsolete technology), fleet commonality, availability of spare parts, noise restrictions, etc... play parts in the decision as well.
But generally speaking, old airplanes are the first to go, rather than new ones. Then again, DC3s out there defy that logic.
Philly Phlyer From United States of America, joined May 1999, 317 posts, RR: 1
Reply 2, posted (13 years 2 months 4 days 13 hours ago) and read 689 times:
The reason that DC3s "defy that logic" (as you posted) is because they are not pressurized. That is what is most tough on an airframe during cycles. For non-pressurized aircraft, the cycles still are important since there is a lot of stress on take-off and landing (especially landing). These, however, do not produce anywhere near the problem of presurization over and over again.
If you keep blowing up a balloon and letting the air out again and again, it gets easier to blow up the balloon as time goes on. This is because the balloon gets weaker each time (each cycle) until it eventually breaks. This is what happened to that Aloha 737 that "lost its ceiling" about 20 years ago.