Aircraft have life-limited components. When you see an aircraft for sale, you’ll see acronyms such as SMOH (Since Major Overhaul). This is important because of TBO (Time Between Overhaul). For example, a typical Lycoming engine has a 2,000 hour TBO. That is, it is expected to last 2,000 flight hours (I think that’s tachometer hours instead of Hobbes hours, but I could be wrong about that). In commercial operation (including rental), that means that the engine must be overhauled at 2,000 hours. Aircraft are also subject to annual inspections. Aircraft in Commercial operations (again, including rental) need to undergo 100-hour inspections. An Annual counts as a 100-hour inspection.
A helicopter has TBO on other components. The rotor blades on a Robinson R-22 must be replaced at 2,000 hours. So you’ll overhaul or replace the engine at 2,000 hours, replace the main- and tail-rotor blades, overhaul the transmission, etc. (A Robinson factory overhaul includes a ‘zero-time’ engine, replacement of components, re-painting and re-upholstering. Costs about $75,000.) A Schweizer 300 has a 2,000-hour TBO on its Lycoming engine, but a 4,000-hour TBO on its rotor blades (around $15,000 each). I think the Schweizer’s tail boom has about a 13,000-hour TBO. I’ve heard that some fixed-wing aircraft have TBOs on their wings; but I’m not sure which, if any, do.
There are also ADs (Airworthiness Directives) that must be complied with in order for an aircraft to remain airworthy. ADs can cover any part of the aircraft, from the engine to the sheet metal. One example is the Beechcraft V35 Bonanza. There is an AD requiring stiffeners on the fuselage under the V-tail because of some inflight failures. Other ADs may cover such things as required corrosion inspections. ADs must be complied with, and they must be attested to by the A&P (Airframe and Powerplant) mechanic.
As long as the components are within TBO, the ADs have all been complied with, and the aircraft passes its airworthiness inspections, it’s good to go.
Compare that with automobiles. There are no longer ‘safety inspections’ AFAIK. (In the UK, they have MoT inspections that a car must pass to remain in the road.) People tend to drive a car until it gets too old, requires more repairs than they want to make, etc. Then they get sold to someone else, who drives it a while and sells it to someone else, and so on until it just wears out and is hauled off to a junkyard. Since people tend not to maintain their cars very well, age is a factor.
General Aviation aircraft are pretty old. The average age of the GA fleet is something like 30 years. In the late-1970s there were as many as 15,000 new aircraft built every year. This ensured a steady supply of new aircraft for people to buy, and relatively inexpensive aircraft for people who couldn’t afford a new one. In the 1980s there were a number of crushing lawsuits. Juries were chosen who knew nothing about aviation, and to them ‘pilot error’ was not an option. It had to be the Big Corrupt Aviation Companies that cause the death of poor Pilot Joe who flew his Cessna into a class 5 T-storm (and without even an IFR rating). In one famous case, Cessna was hit with a $40 million judgement when a pair of pilots – a husband and wife – flew into a T-storm. Even though the NTSB determined the engine was working normally, Lycoming was hit with a large judgement as well. Juried just wouldn’t listen to facts, and were persuaded that the Aviation Companies must be culpable. (Okay, that was a bit of a rant. Sorry.) Another factor was that the aviation companies were liable for every aircraft they’d ever built! :eek: If Piper built an airplane 50 years ago, before some sort of technique or material even existed, they could still be held liable for a crash. Congress reformed that bit, and now they are only responsible for aircraft built within the last (IIRC) 18 years. Still, can you imagine Ford being held liable in a fatal crash when the car was built before airbags?
The upshot was that GA aircraft production came to a screeching halt. Instead of 15,000 new units, 1,200 was considered a good year. Piper went through several bouts of bankruptcy, and Cessna stopped building single-engine piston aircraft (the kind everybody flies) for a decade. Used aircraft became more and more expensive. Aircraft that might have previously gone to a boneyard were now kept in service. Hence, an older fleet.
Still, there’s nothing really wrong with older aircraft. Yes, there are articles such as ‘How Old Is Too Old’ in AOPA and Flying; but as long as the aircraft are properly maintained, there should be no problem flying them.
Again, maintaining an aircraft is expensive. It’s cheaper to have an existing engine overhauled than it is to buy a new engine or to put in a ‘zero-time’ (factory rebuilt) engine. Engines are subjected to constant operation and temperature extremes. (Consider also that if an airplane operates at 140 mph, then at 2,000 it will have 280,000 miles on it.) A lower-priced overhaul might keep a serviceable cylinder, even though there may be an undetected flaw in it. (If there is a known problem, it must be replaced.) So an older aircraft that has had the least-expensive maintenance allowed by law is more likely to develop a problem inflight. The same aircraft – even if it’s 50, 60 or 70 years old – that has been the benficiary of higher-quality maintenance would be less likely to have a problem.
So in short: It’s not really the age of the aircraft, but how it’s been maintained.
(Incidentally, when was the last B-52 built?)