Quote:
Originally Posted by TheFly
Does anyone know the lifespan of the airframe of the bus vs Boeing?
Doing a quick search on-line, the 737 has been tested for 60 or 75,000 cycles (depending on Classic or NG); the A-320 is 48,000 cycles and 60,000 hours.
I did a paper on airframe fatigue for a Master's class 20 years ago (
). At the time, there had been three notable fatigue-incidents, of which the Aloha 737 was the most famous, as well as the United 747 that lost the forward cargo door (and tore off significant skin when it departed; 6 died).
Boeing at that time maintained that their airplanes had an unlimited life. While there were recommended cycle limits, they were not compulsory. It merely meant that if you went beyond those recommendations, it was likely to cost more money to keep it airworthy.
I found a reference (back then) that showed the cycle/hour comparisons for the 727, 737, and 747. The hour to cycle ratios were proportional to the type of flying each was anticipated to fly. The 737 was lots of cycles, short trips. The 747 was given more hours, but fewer cycles---indicative of long-haul international flying.
Interestingly, the SWA 737 that blew out the cabin a few years ago had only achieved one-third the expected cycles. There is significant concern that the cycle testing (typically done using only a fuselage shell mounted in a test rig) does not realistically simulate revenue service. No hard landings, no twisting/torsion due to turbulence, no spilled sodas seeping into the lap-joints, no being parked in a humid environment for days on end, no catering truck dings, no jetway dings, etc.
I would guess the Airbus limits are similar.
In military service, other than being made obsolete by new threat technologies, one of the biggest factors 20 years ago leading to airframe retirement was not the airframe per se....it was wiring. It seems that in the late 1970s/early 80s, a new wire insulation called Kapton became all the vogue.
Unfortunately, it turned out to have a limited life, especially in salt environments. Lots of Naval aircraft were grounded because the wiring was shot, and it was cost-prohibitive to replace the entire wire harness of a fighter.
I can't help but wonder if the Bus, with a fuselage designed three decades after the 737, has a better method of routing wire bundles, that would make it easier to replace, if necessary.
When you see someone flying a restored WWII fighter, and knowing all the yank and bank it has been through, years of neglect, corrosion, and restoration, it makes me believe that with good maintenance, one can keep an airplane flying almost indefinitely.