I was a little surprised to hear of the mothballing of the Gimli Glider as it was a 767 and to me that’s a “modern” plane.
The incident occurred in 1983 and the plane was commissioned in 1981, so that makes it 26+ years old. I’ve seen lots older around airports (727’s for example).
It varies between aircraft type, but the upper limit on an airliner’s life expectancy is based on it’s airframe-life. The airframe being the principle structural components (wings spars, fuselage, etc.) These components go through stress cycles with every take-off and landing. Currently IIRC the upper limit lifespan is about 60,000 airframe hours (or 30,000 cycles). Each take-off and landing is one cycle. Eventually you will get fatigue cracks that will effectively resign the aircraft to the scrapyard.
There are plans in place by some aircraft manufacturers to effective double the allowable airframe hours on its aircraft with structural upgrades.
The real actual-factual airline pilots and aerospace engineers (I’m only one by training!) will of course expand on this.
A recent news item about the 767’s fuel economy implies that the intended service life of the 767 is 40 years.
26 years would seem to be on the short side, but realistically, an airplane will last as long as its owner feels it is economically viable to maintain it, and for as long as it remains airworthy.
There are a number of possibilities why this one’s getting early retirement - inspections may have found frame damage that’s not economical or possible to repair, or the airline is phasing out or trimming down its fleet of 767s, or John Travolta wants to buy it.
The 737’s design life is something like 70,000 hours and 60, 000 cycles. Of course, if you’re willing to keep repairing it, you can stretch that; but aluminum has a definite fatigue life, so the cost of repairs is going to go up pretty quickly after that. (Unlike steel; if you design a steel thing so that the stresses are low enough, it can last forever.) Airbus is currently looking at what it would take to keep A320s in the air for 180,000 hours.
Compare that to an automobile: 150, 000 miles at 30 miles per hour is only 5000 hours.
DC3’s built in the 1930’s are still in use around the world mainly by small operators in 3rd world countries.
One of my favorite factoids is the B-52 (not truly a commercial airliner but plenty of military personnel ride in the them) is expected to have a service life past 80 years. It is the U.S. primary strategic bomber and is nuclear capable. The military has tried to replace it several times and no one could come up with a better design. They don’t plan to retire it until at least 2040. The B-52 fleet has flow from the U.S. to Iraq and back without stopping many times delivering a huge deadly blow.
This might be a real possibility, given that it’s had at least one unusual landing that everyone is aware of. Hard landings can contribute to the lifetime stress and shorten the life of the airframe. I’d prefer they retire it early than have it involved in a destructive accident.
Air Canada is indeed phasing out its older 767-200s, but will continue with its 767-300’s. They’re bringing in new aircraft – 777 and 787 – with improved performance. (The plane in question, C-GAUN, is one a 767-200.)
In particular, one of the main motivations for retiring aircraft seemingly early in their service life can be lower operating costs of newer aircraft with newer engines and lighter airframe construction.
That has always intrigued me. I think I heard that about the B-2, that they were flying missions out of Ohio or something. That seems like it would be very odd, living at home in America while dropping bombs into a war zone.
There’s a lot of thought that goes into it. I was talking to a Boeing engineer once, and he told me that all the components of an aircraft are designed to a specific service life under typical use. So a long-range plane, like a 747, is designed for one takeoff-and-landing cycle for every 8 flight hours (or something like that). But Japan Air Lines (I think) had such heavy traffic on the Tokyo-to-Osaka run that they wanted a 747 they could use like a short-hop, eastern-U.S. shuttle. That meant beefing up the landing gear, to survive one cycle per 1.5 flight hours.
I’ve heard there are current B-52 pilots whose fathers, and grandfathers, have flown the same plane. And it’ll be a fourth generation before they’re phased out.
One limiting factor in the case of commercial airlines will be the advent of technology which will reduce the operating costs.
Better fuel efficiency and desined in lower maintenance costs will probably make it too costly to operate an older aircraft if your competitors are keeping up to date.
On the other hand, retiring a plane early and putting it into storage when you upgrade to a new model might also be of benefit. They could, for example, sell the airplane (which still has life on the airframe) to a lower-budget airliner or cargo carrier, or perhaps pull it back into service to replace an airplane destroyed in an accident until another new airplane could be purchased. I don’t know the economics of running an older less efficient plane on a route to keep the customers coming vs. canceling all those flights until you get a new airplane but I’m positive someone somewhere has the numbers crunched.
The B-2’s are all based at Whiteman AFB in Knob Noster, Missouri. They did indeed fly regular missions to the former Yugoslavia from there, roughly 14 hours each way. That protected security, and saved the expense and inconvenience of a forward deployment, but required a lot of tanker availability.
In the first Gulf War, there were some B-52 missions flown to Iraq and Kuwait from Louisiana and Guam, but not when the demand on limited tanker availability became too acute.
The practical life of an airliner depends, as you might expect, entirely on economics, and that in turn is dominated by fuel prices. In fact, roughly a third of the total operating cost of a major airline is typically fuel alone. Yes, that means that nothing anybody can do about scheduling or customer service or anything related to operations, as is the case for other industries, matters nearly as much to the bottom line as the success of its fuel price hedging strategies. But there is no ultimate hard limit to its life; it’s just that the cost of the maintenance and inspection required to keep it going increases to an uneconomic level. That level in turn depends on the airline and its market. Entire departments exist to constantly crunch the numbers and define strategies.
Engines and airframes have become much more efficient today than even 10 years ago, due both to advances in use of composites and to the maturation of aerodynamic simulation codes, as well as other factors. An airplane can become economically obsolete long before its fatigue cycle count gets up to where a change in inspection frequency becomes required.
But US airlines do typically plan for 20-25 years of life, before selling them down to the Third World or shoestring charter lines.
The DC-3 wasn’t pressurized. When pressure is added the airframe expands a little, then it shrinks when pressure is reduced. This can result in fatigue cracking. Since DC-3s’ cabin pressure is the same as atmospheric pressure, they don’t have this particular problem.
The Lockheed Electra’s were pressurized, though, IIRC. I flew on a charter service that was operating a couple in the late 1970s, and it appears there are still a handful out there.