So I am looking at a C-172 at the moment and it has 25,1XX hours on it. It is a 1982 P model with Penn Yan 180HP and 2550 GW increase, along with heaps of other good STC's that elimiate some AD's, or reduce or remove periodic inspections of some stuff. it does have Cessna SID's done in 2012 (made mandatory in Australia).

Aircraft was used in a flying school its entire life and maintained by the flying school's maintenance arm. Obviously averaged 675-ish hours per year over that time, so has had at 6 x 100 hourly inspections done each year.

Aircraft apparenlty flies well, is smooth, well rigged etc (we have not yet got a pre-purchase or flown the aeroplane). But how many is too many hours? I am an aeronautical engineer by degree and am well aware of fatigure, work hardening, aluminium reaction to vibration etc and this many hours does give me pause. If the aircraft wasn't otherwise in perfect order with a great instrument fitout (twin G5's, G500 autopilot, 430W, ADSB-out, fully IFR, new interior, paint average) I wouldn't even be asking. But it appears to be a very very nice aeroplane. Mine and my potential partener's use is around 400 hours per year (so read 200-300 hours realistically, I would use it during the week and he on weekends - perfect!).

Second question would be, what is the value? Is it the remaining engine value plus avionics value on the second hand market? is the airframe worth anything other than scrap value? (not after a dollar figure as the markets between Australia and US are very different - just a subjective/qualitative assessment on what it may be worth). The current owner knows he has over capitalised considerably, but obviously is looking to get some of his over investment back.

Oldest aeroplane I have flown is a 12,000 hour (was also a C172!) and it flew great but this is over twice that.,

Any advice very much appreciated.

Cheers
Dave

Hey Dave, the Aus market is flat, it's a good time to buy but many sellers are still unrealistic. The P's fly nice and it sounds well kitted out. Be aware the flight training history will put it in the Severe Utilisation category for the SID's and thereby reducing the recurring inspection intervals significantly. The US guys don't realise how lucky they are not having to waste money on SID's...

The seller will never recover the cost of the avionics and autopilot, maybe 1/3 of the $$ spent, but they certainly add value for the buyer. The dual G5's, GFC500 and 430W is a very capable combination. Fatigue is definitely a concern, but I would also consider maintenance induced 'damage' given the amount of work that's been done on it over the 25k+ hours. Who did the SID's is also a factor. There's SID's and there's SID's.. I've seen some supposedly SID 'compliant' aircraft that are in poor condition. It's a fact that some shops cater for the owner that can't really afford to do the work correctly

There's limited buyers in Aus, so depending on engine time, it may be a sub $60k plane with those high hours. Early 172R's and S's are occasionally selling for under $90k with the odd G1000 172 selling for very low $100's..

Have an engineer you trust go over it with you and if ok, buy it and fly the wings off it

I have flown pipeline older 172s in the 30,000+ range that flew well. Interior plastic and fiberglass cowl and fairings do not hold up well. The older all aluminum with good patches were better. Seat rails and battery boxes require extensive upkeep. Maintenance free battery helps a lot. I have flown airplanes that needed firewall behind the battery repair. Hopefully the newer models have addressed those issues.

The following is generic and listen to the other guy about australia specific issues...

I was previously in the camp of "over 10,000 hours is junk" and I think thats true of many airplanes especially older ones such as 40's-50's Cessnas (170s, early 180s). However, if you count the rivets and doublers on Cessna's, they greatly increase over time. The airplanes get heavier but also in my opinion stronger. It seems to me that sometime in the late 60's, Cessna had an epiphany that these machines weren't going anywhere for a long time and started beefing them up. I think 172's are an incredibly strong airframe. If you got this airplane for a good price and those avionics and mods will make you happy for the next few years, I'd say go for it. This of course relies on the fact that you get a good prebuy that is especially attentive to airframe fatigue. When the time comes to sell, the next seller will be having the same questions you do, that's about the only downside. That, and the fact that you have to accept the fact that a bunch (hundreds) of rando's have twanged your baby onto the asphalt thousands of times. Buying from a private buyer, you get the satisfaction of knowing through registration history all the 10 rando's that twanged it onto the asphalt.

My outlook on airframe times has changed, probably because I'm now flying airplanes in the 20,000-40,000 hour range. C206's, C207's, Bonanza, Cubs. For any airplane, lower is better, but for many airframes, it doesn't matter that much. If you fly 1000 hours on this thing, the hours will go from 25k to 26k. Not much change there, so it's unlikely that the airframe showing bad signs of age will all of a sudden begin in your time as owner.

The highest time airframe I fly is my current favorite. It flies like an old pair of jeans and has all the kinks massaged out. Quality of maintenance over the years is what makes it that way though I suspect.

Are there any real metal fatigue issues with high time Cessnas?
Worn out parts, sure. Corrosion, you can have that in a 500 hour airplane.
But actual metal fatigue?

I'm not bothered as much by high time so much as high time coupled with student training. I've never flown a 25,000 hour airframe, but I've flown a couple in the 10-12,000 hour range that hadn't been in student use, and although neither of them were cosmetically attractive, they were good, solid, serviceable airplanes. The 172 was bare bones and missing some formerly installed instruments, so it had holes in the panel, but the navcom and transponder worked just fine, as did all of the flight instruments. The 182 had a semi-working auto pilot and a gen-yoo-wine Northstar LORAN-C which actually worked (although I wasn't smart enough to make it tell me anything). Neither had been painted since leaving the factory, and both had been tied down their entire lives. Both had ratty upholstery and cracked and broken plastic inside. I couldn't happily own either of them, just because I like owning things that look better than either did, but I had no hesitancy renting and flying them.

But I've also flown some airplanes that were cosmetically reasonably attractive, but they had been beat to death in student use. Students can be incredibly hard on airplanes, especially to the landing gear. So that would give me great pause in your situation, as you've said that this was a student trainer.

My suggestion: when you have the prebuy done, have the mechanic give special emphasis to the main gear boxes (which are horribly expensive to replace) and the firewall and nose gear (equally expensive). Those are the things that get the most wear and tear from students. If there have been repairs to any of that, make sure that the repairs were done correctly. Just because they were signed off by someone with the right credentials isn't a guarantee that the work was done properly.

One final comment: would I buy a 25,000 hour flight school airplane? No.

Cary

Another big part of this might be asking yourself if you envision this as a long term airplane (see also: emotional connection) or a temporary means to an end, even if that end is simply having fun flying.

Thank you all for the replies, some great information and opinions.

So my potential partner and I discussed this at great length, spoke to three different LAME's about it. Two said with a good prebuy/100 hourly and particular attention to known cracking / loading spots, you could be fairly confident of getting a decent aeroplane. Indeed it was in a school for all but the last 450 hours of its life so it WILL have been abused by students.

The last LAME said "run for the hills" and put a value on it of scrap and didn't value the avionics, which might be ok for him, but they do hold value for us. He also said Cessna's are life limited to 30,000 hours. I don't think this is correct, in fact I don't think they have a life limit on them at all, certainly any of the strut braced C1XX series. I could be wrong.

The other two gave a value somewhere close to what we were thinking of it. Basically about scrap value for the airframe, plus between 30% and 50% of the cost of the avionics and a little more than core value for the engine (it has 450hours to run).

Both my partner and I are very fair people and as such, we did not want to offend the seller by giving him a "low ball" offer, some could say realistic but, tomato tamarto... So we went back and said words to the effect of "the aircraft, to us, is not worth what is being asked, it may be to other buyers, but as our offer is considerably less than what you are asking we don't want to offend you with what you may see as a low ball offer". My partner and I both thought that this would give him, a chance to say "what would your offer be?" if he was interested in selling, but he just said "no problems, thanks for getting back to me".

So obviously we are going to pass on it. He has my contact details so if he does find that perhaps his over capitalisation does not mean he will get anywhere near what is being asked, he can always come back to us.

Thanks once again for the replies here. I came here to ask the questions as (except for one or two threads!) people on this board tend to give well thought out and reasoned responses based on years and years of personal experience. Go to most other forums and you just get the usual "unhelpful" responses...

Cheers
Dave

Good decision Dave.

Here's a little anecdote. My buddy and I trained in a flight school 172 which had comparably high hours.
Months after my buddy finished training, the plane was flipped over by a freak wind gust. When assessing the machine for repairs, the LAME found an extensive but hidden fatigue crack in the aft fuselage superstructure. The crack was so serious, that the fuselage was scrapped for parts. That crack would have escaped detection apart for the accident. As you'll know, once the crack reaches the critical flaw size, the tail cone is coming off suddenly during a high g-turn or turbulence. That really put us both off high-hour airframes.

I cannot argue with your decision to pass on the airplane. Given the facts you presented, I probably would have made the same choice.

That said, the LAME who stated: "He also said Cessna's are life limited to 30,000 hours." needs to provide a reference for that statement, or admit that he is wrong about it. I cannot find anything in the TCDS for the Cessna 172 that documents any time-limited components (other than the engine and possibly propeller, which have their own TCDS).

These days, it is getting harder and harder to purchase one of the newer 172s (70's and up), because they are in such high demand by flight schools, who are ramping up training to meet the airline pilot shortage. They can afford to overpay for a decent airframe, replace the engine, update the avionics, and STILL come out way ahead versus buying a new $350-400K airplane from Cessna. In our area, there are at least five flight schools snapping them up and refurbishing them. Prices for 172s now rival 182s, which are in a lot lower demand.