Sara From Netherlands, joined Feb 2008, 0 posts, RR: 0 Posted (14 years 7 months 3 weeks 6 days 23 hours ago) and read 815 times:
I responded to your post "UA Better Have Good Mechanics" with a question. I realize you probably thought the question was either a joke or too silly to answer. I really am curious ,though, and would like to know if you can give me an answer. If not, I'll ask someone else so they can ignore me as well
JETPILOT From United States of America, joined May 1999, 3130 posts, RR: 29
Reply 1, posted (14 years 7 months 3 weeks 6 days 22 hours ago) and read 723 times:
In theory aircraft can continue to fly forever as long as the airframe (fuselage and wings) does not crack. Parts can be continually replaced. I use to fly a 38 year old DC8. Believe it or not it is only about half way though it's useful life.
In reality aircraft like cars offer diminishing profitability the older they become. Part replacement becomes more extrensive and expensive, The parts for older airplanes like the DC8 are not new parts but are cannabalized from other aircraft that have fatigued beyond what has become proffitable.
An aircraft reaches a point where the sum of it's parts exceeds it's total value and ability to create revenue. So the replacement parts are limited due to available existing airplanes being parted out.
The government lays out maintenance scheduals for a particular model of aircraft which needs to be followed by the operator of the aircraft in order to maintain the airworthiness and value of the aircraft. An aircraft that is not maintained by these regualtions are worthless on the market since they cannot legally be flown. So there is much incentive to maintain an aircraft.
Contrary to popular belief maintenance is the same from one airline to another.
24291 From , joined Dec 1969, posts, RR:
Reply 2, posted (14 years 7 months 3 weeks 6 days 13 hours ago) and read 700 times:
I sincerely apologize--I seem to be having this problem with all the ladies in my life lately.
As for your question, JETPILOT pretty much hit the nail on the head, but I'd like to add a few things. While maintenance guidelines are the same for a particular commercial aircraft, that doesn't mean an airline can't exceed them if they desire. Additionally, some airlines with less cash flow may cut corners and it may eventually lead the carrier into problems with the FAA.
As already mentioned, the theoretical life of an aircraft is indefinite; however, airliners get a lot of abuse, regulations change, and more efficient equipment becomes available. These factors combined limit the "useful" life of an aircraft. There are many 30-year old "Frankencrafts" serving with U.S. airlines today--particularly with Northwest. Eventually, these will be sold to secondary markets, perhaps converted to freighters, and they'll serve significantly longer. In the end it comes down to money.
I'd also like to point out that an aircraft's age is determined more by its flight hours and number of cycles than years. Aloha operated a 737-200 that was by no means the oldest aircraft flying, but the high-cycle environment, frequent pressurization, and the salt air eventually caused the fuselage to fail spectacularly in flight. This is a good example of how planes become more expensive to maintain as they get older; Aloha must now be very diligent in inspecting for cracks on their older aircraft.
Another example: The B-52 was introduced around 1954. It's still serving the U.S. today, and it has been announced that they'll will continue to be utilized until around 2037. The "newer" B-52s are only about 38 years old, but that still puts them around 75 years old when they are retired! Most B-52 crews already are younger than the airplane they fly. It amazes me that such an old design can still be viable. Then again, the government doesn't have the same financial constraints as the airlines.
I saw a vintage WWII B-17 recently here in my neck of the woods. It was a beautiful airplane! It costs them an arm and a leg to maintain those things, but it's worth it; they are flying history and the sound of those engines is unlike anything we're familiar with today.
I am by no means an expert on the subject, but I hope that gives you something else to think about.
Sara From Netherlands, joined Feb 2008, 0 posts, RR: 0
Reply 3, posted (14 years 7 months 3 weeks 6 days 6 hours ago) and read 670 times:
Thank you JETPILOT and 24291 for all that neat info. ( and for humoring a novice).
I noticed you are from Farmington. I too saw the WWII aircraft several months ago at your airport! My father dragged me down to see them. He is a HUGE aircraft enthusiast, hence my desperate attempts at gaining knowledge through you guys. If you had to fly in one of those things during WWII, what job would you want? I would be the bombardier, because they seemed to have the most room. I know it's another silly question, so you don't have to answer this one.
24291 From , joined Dec 1969, posts, RR:
Reply 4, posted (14 years 7 months 3 weeks 6 days 5 hours ago) and read 664 times:
It is a small world!
Once you have been with this forum for a while, you'll realize that you would be hard-pressed to ask a question that's too silly! Also, simple-sounding questions sometimes yield very complicated and interesting results. As for your earlier question about aircraft age, I hadn't realized you were asking me specifically. I'm sure there are many here who could give you a good answer to that one.
As for the B-17, I would want to be the pilot! If I couldn't do that, I'd want to be a gunner, so I could at least watch the other airplanes as I shoot them down. The ball turret would definitely be one of the scariest places to be--I don't think I could handle that.