How many years a commercial jet can be used?

Question

In my country, lots of jets are more than 20 years old. can anybody explain, is there any world regulation for that.
I think many of plane-crash accidents were caused by 'too old' airplanes.

thanks

Answer 1

No, there are no regulations or an age limit on how long an aircraft can be in service. So long as it is maintained according to regulations, it can be operated. Simply being "old" doesn't cause a plane to crash unless it was not mechanically maintained.

Also, the "lifespan" of an airliner is not truly measured in time, but pressurization cycles. Each time the aircraft is pressurized during flight it's fuselage is subjected to stress. The "lifespan" of the aircraft is reached the metal fatigues and cracks.

The "service life of 20 years" is as generalization that figures 51,000 flight hours and 75,000 pressurization cycles for most aircraft. If an aircraft is used on long haul routes it experiences relatively few pressurization cycles in it's "life" it will last far beyond 20 years. Only a few years ago, the "average' age of a jet in the operating fleet of Northwest Airlines was 20 years according to a 1999 article. A 2005 news clip noted NWA continues to operate DC-9-31 aircraft that have an average age of 34 years old!

Aircraft that are repeatedly flown on short hops, with many pressurization cycles, will reach their useful life much sooner. For instance, the famous Aloha Airlines incident on April 28, 1988 where part of the fuselage broke away due to metal fatigue is an example of the latter. The aircraft had accumulated 35,496 flight hours and 89,680 flight cycles and was 19 years old. Very close to that 20 year mark, but her actual cycles flown was the amount expected of a much older aircraft. Due to the low altitudes their inter-island flights were flown, we can be sure the maximum cabin pressure differential of 7.5 p.s.i. was not reached on every flight, so the number of full pressurization cycles on the accident airplane can be interpolated to be less than the total 89,680 cycles (a takeoff & landing) accumulated on the airplane. However, it was still enough to cause significant fatigue in the airframe and is still a much higher number than 75,000 cycles predicted for a 20 year service life.

Answer 2

As far as I know there is no regulation to how old a plane can be before it has to be replaced. How ever a plane has to pass air worthiness so if its a 20 year old plane, but can still pass air worthiness then it will still fly.

But after a while passenger airlines replace their fleet for more modern planes because they are more comfortable and have longer range.

I don't believe that plane crash accidents were caused by too old airplanes. It all depends on how hard the plane was worked. The constant pressurization and pressurization can cause stress on a planes fuselage. So if there is a 20 year old plane that has only flown 600 hours, or a 5 year old plane that has flown 600 hours, which one will be more dangerous? the 5 year old plane most likely due to being over worked.

Alot of older passenger planes are converted to cargo planes. Like the Boeing 707 and most 747-200

Answer 3

There isn't an established number of years or cycles yet. The reason that a lot of airlines upgrade to newer aircraft is for operating expenses. I have worked on DC9's for almost 27 years. All of our aircraft are from previous operators. Soon, we will be retiring the aircraft. "C" checks and progressive inspections have become more and more involved. The corrosion control program has become very extensive. More often than not, an inspection will turn up a discrepancy on a principal structural element putting the aircraft into a major repair. There comes a time when an airline must choose between the cost of maintaining an older aircraft as opposed to the finances of a new one. The DC9-40 that I inspected today was built in 1971. It has to have three major repairs (P dome, rw rear spar, and horiz stab rear spar). Another check like this one, and the old girl may be headed for the bone yard.

Answer 4

im pretty sure different airlines have different age limits occur below the standards. for example:
the rregulations may say that a plane has to less than 35 years old to fly commerically (i dont know the figures)
well most airlines would set themselves a limit of 20 or 25 years before they retire a plane because it would be to costly to keep them running beyond this age.
however it sounds as though the airlines in your country are relitively new so instead of buying new planes they are buying old planes from other airlines, i would not be too worried, thier is only every a handful of plane crashes per a million or two flights, therefroe you would have to be unlucky to be caught in a plane crash.
fly qantas, in their whole operating period of over 50 years they have never had a serious plane crash or fatality.
happy holidays!

Answer 5

Well, the Douglas DC-3's are still flying over 50 years now, but because they are not pressurized, they don't have as much stress on the airframe.
McDonnell Douglas used to warranty there commercial planes for 20 years.
The B-52 is about 50 years old, also.

Answer 6

There really isnt a life expectancy for any given aircraft. They can fly indefintly, assuming proper maintenance. Newer designs incorporate new efficiencies, avionics, engines, etc. However old aircraft, can be refitted with new engines, avionics, etc as well. It really just depends on what the company that is operating them wants to do with them. Its an accounting/insurance/budget/tax advantage game.

Answer 7

20 to 25 years is the normal service for commerical use... They can then be used for freighter use