Date: 16 Aug 99 22:28:15 From: firstname.lastname@example.org (James Matthew Weber) References: 1 2
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On 07 Aug 99 01:22:56 , "Philip J. Kuhl" <email@example.com> wrote: >My understanding, and I'll gladly be corrected by those more knowledgeable, >is that the total amount of time on the airframe is not so important if the >appropriate maintenance is kept up. I believe this leads to so much of the >aircraft being replaced over time that little, if any, of the aircraft is >"original" after a given number of years. I vaguely recall from decades >past that after an airliner had been in service for about seven years in the >U.S. essentially all of its parts had been replaced. Replaced, no, however at a D check, the aircraft is essentially taken apart. The problem is parts are expensive. Have you ever priced the cost of your car if you were to assemble it from spare parts? The finished product has to be price competitive, once you have bought the product, you are stuck, and spare prices may not be so attractive. In theory, you can keep replacing parts, however technology changes, and between the cost of the parts, and the poor operating economics, at some point it will cost more to fix than it is worth, or the operating costs get very high. For instance if the price of Jet A were to double (which has almost happened at least once), a large number of 747-100/200's would probably cease flying. A 747-100 at high weight with early PW engines burns about 25% more fuel than a GE CF6 747-400 to carry fewer passengers and cargo. Today that extra fuel may cost $5,000 per flight, or perhaps $200,000 per year. If price of Jet-A Doubles that cost doubles, and that may be enough to move the operation from profit to loss. At some point the aircraft is no longer economically attractive to operae, and that is usually the point you take the aircraft apart and sell the parts that may be valuable still. This has already happend to a fair number of early 747's.