Wadha From United Arab Emirates, joined Mar 2000, 185 posts, RR: 0 Posted (13 years 3 months 1 week 2 days 20 hours ago) and read 750 times:
As a flight attendant, i experienced working on old aricrafts and new aircrafts. i want to discuss when is it the right time for an airline to replace the old planes of its fleet. I.E after how many years. when an airplane gets older, it starts to appear that this airplane is not new.
BigGiraffe From United States of America, joined Jan 2000, 257 posts, RR: 0 Reply 1, posted (13 years 3 months 1 week 2 days 19 hours ago) and read 637 times:
The airline must weigh the cost of buying a new aircraft against the cost of refurbishing the old one.
For example, American Airlines has refurbished the interiors of some (many?) of its 727 aircraft so that they look newer than some younger aircraft on other carriers. This was cheaper than a new acft, but the 727 uses a 3-man crew and the engines aren't as economical as younger models. It was a business decision. They will no doubt replace the acft before too many more years, but the refurb was their choice until then.
Eventually an acft moves into the "Aging" category and all sorts of special structural inspections have to be tracked and accomplished at the right times. And the reason they are inspecting is because the manufacturer expects problems to begin, so besides the inspections they begin doing more repairs. This tends to speed the decision for replacement.
Technically, you can operate an acft indefinitely as long as you continue to spend money on increased inspections and repairs.
Seb146 From United States of America, joined Nov 1999, 9914 posts, RR: 17 Reply 2, posted (13 years 3 months 1 week 2 days 10 hours ago) and read 605 times:
Besides the cost of inspections, there is another economic factor. It's about getting as many people between point A and point B with as little money spent on aircraft as possible. I would love to take a 707 anywhere, but the airlines would lose passenger revenue because there are fewer seats on a 707 than a 767. Add to that the fact that it costs less to operate a 767, and we fade out the old aircraft.
AC183 From Canada, joined Jul 1999, 1532 posts, RR: 2 Reply 3, posted (13 years 3 months 1 week 1 day 17 hours ago) and read 580 times:
There's nothing wrong with older aircraft if they are well cared for. And sometimes the build date is quite misleading. An aircraft with hushkits or a different engine, avionics updates, and thorough refurbishment and mechanical inspections/repairs can fly reliably for a long time, and in fact be quite modern. The big factor to keep in mind is not the fatigue life of the airframe, however, but rather the economic life. At some point it does become worthwhile to buy newer equipment. But in actual fact, when it comes to structure aircraft haven't changed a whole lot for 30 years, so other than some refinements of the newer models there isn't a huge difference to really make old ones obscelete.
BigGiraffe From United States of America, joined Jan 2000, 257 posts, RR: 0 Reply 4, posted (13 years 3 months 1 week 1 day 7 hours ago) and read 567 times:
Fatigue life does play a significant role in economic life. Your inspection burden increases with airframe age and that definitely impacts your dollars. But as long as the airline feels the aircraft draws in enough profit to offset the aging aicraft costs they continue to operate them. Another thing about fatigue life is that the whole airframe doesn't reach that point at the same time. The landing gear backup structure may reach end of fatigue life first; at that point you can repair or replace it and continue operating. Maybe the vertical stabilizer attach fittings come next and the same decision can be made. You can operate an old aircraft indefinitely as long as you maintain it (includes repairs and replacements as required).
There are some subtle differences in new airframe designs that make them better. There are improved metal alloys out. The industry also learned a lot about the older alloys and how they should be incorporated into designs. Some, such as 7079 aluminum, simply aren't used anymore. Others such as 7075 aluminum are still used, but either aren't heat treated to such a high strength or are designed with less stress running through the member, or both.
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