As aircraft maintenance Technicians we all know that a rule has been issued that most of the aircraft steel parts has been life limited to maximum of 12 years , of service , after which the item should be removed from the aircraft and overhauled and NDT inspected.such as main landing gears , crankshafts, attach pins , flap carriages , etc...
My question is that , is there any FAR requirements or statement for such limitations. and on what basis the manufactures has limited the life of such components.
Thanking you in Advance
FAR Requirements for Life Limits