Does age of an airframe matter?

[Trow28]

A lot of the aircraft I've been looking at on-line are late sixties model years.  That's ~55 years on those bones.  If I find a forever plane and I'm looking to fly for the next ~25 years that would be 80 years on the airframe by the time I'm ready to sell.   

Have their been any studies on the usable life of 60's era airframes?  Is it safe for me to assume all will be well if I have an pre-buy inspection and then take care of the plane while I own it?

[DCarlton]

You ask very hard questions.  It will be interesting to see the response.  I'm not a mechanic and not an expert.  My thoughts.  I like your idea of buying the plane that you want to keep long term and just keep making it better.  Making it the newest can't hurt.  I wanted a newer J at the time but could afford an F.  As far as assuming; don't do it.  Regardless of the process, there will be surprises down the road.  Hopefully if you're lucky, a pre buy or annual with catch any major issues.  As far as airframe ADs, look at all the other planes that are on the market other than Mooney.  Many have had airframe issues over their lifetime; Cessna, Bonanza, Piper, Commander.  Fortunately most could be addressed.  At this point, if my Mooney ever has a major issues, I'll probably just part it out.  I'll be OK.  BTW, I asked my mechanic the same question about six months ago (any reason not to fly a 55 year old airplane until I'm done flying).  Let's see what others say.  

Edited March 12, 2022 by DCarlton

[0TreeLemur]

35 minutes ago, Trow28 said:

A lot of the aircraft I've been looking at on-line are late sixties model years.  That's ~55 years on those bones.  If I find a forever plane and I'm looking to fly for the next ~25 years that would be 80 years on the airframe by the time I'm ready to sell.   

Have their been any studies on the usable life of 60's era airframes?  Is it safe for me to assume all will be well if I have an pre-buy inspection and then take care of the plane while I own it?

Acknowledging that nothing lasts forever, it is a question of remaining life.   Corrosion is the airframe killer.  When I bought our C that was distant knowledge.   A year after buying our '67 C and learning more about Mooney corrosion issues, I took our airplane to a MSC for a detailed 208-B and spar corrosion inspection.  Fingers crossed.  It passed with high marks.  Our C has lived in many places, but spent over half of its life in the desert SW and very little time in coastal regions.  Significant, unhangared exposure in coastal environments is a red flag.  Since log books don't note whether or not an airframe is hangared, the only way to be sure is to have it inspected by someone who knows what they are looking for. 

[carusoam]

Age itself doesn’t matter…

But, the number of years allow a lot to happen….

So…. With aluminum Mooney airframes… there isn’t a number of cycles we are counting…. Or forced OH on things because there is no historical data to prove it is OK….

Keep in mind this is true for GA in the US… Canada has some age limitations that may require an OH for some things…

All wear items are replaceable…

Every now and then… you may see a smoking rivet… a sign that it may need to be replaced…

 

Paint wears thin after several decades… when kept outside…

Windows oxidize on the outside surface…

All updatable.

 

Corrosion is bad if it occurs… but not age related… more of a care issue… how best to care for your Mooney…

 

When selecting a Mooney… newer airframes have updates that older ones may not have…. Check to see what updates an older Mooney has….

The Best M20Js came near the end of the line…. The first ones are still pretty awesome and they are called M20Fs… 

 

Go Mooney!

Best regards,

-a-

[Fly Boomer]

8 hours ago, carusoam said:

All wear items are replaceable…

That's the nutshell.

[A64Pilot]

As an A&P/IA I’ll argue that age DOES matter. there are forms of corrosion that are age related as well as fatigue. Ideal world we would all buy zero time aircraft, but as there are no new Mooney’s and finances are often constrained that's not happening 

However it’s just one of many factors that are important. How it was kept, where it was kept, airframe hours, was it ever a training aircraft, was it substantially damaged in the past and if so was it correctly repaired etc.

But Corrosion is why aircraft die, it is the eventual killer of most, and it to a great extend can be mitigated and pretty much arrested, by keeping one inside and liberal use of Corrosion-X, other products may be just as good, but I have significant  experience with Corrosion -X and it works.

Having said age does matter, when I get my alternator back from the shop I’m going flying in my 1946 Cessna, I believe correctly maintained an aircraft can last all most indefinitely. I certainly expect the Cessna to still be flying when I’m in the ground anyway and it was born 12 years before me.

So in your pre-buy inspection look very hard for two things corrosion, and any undocumented airframe repairs, if you find undocumented things then you don’t know the history of the airplane, speaks to me that someone has actively hidden things, and that’s not good.

Then finally once your feel sure your going to purchase the airplane have the pre-buy turned into an Annual, people will argue but most look harder when they are Certifying an aircraft as Airworthy in an Annual. They don’t do that in a Pre-buy and as an example on this Forum there are a couple of examples where the pre-buy went great and the first Annual was a disaster with severe corrosion, one was even the same shop that did the pre-buy. 

On edit, the older an aircraft is, the harder I look, especially for corrosion.

Edited March 13, 2022 by A64Pilot

[RLCarter]

Age doesn’t bother me as much hours, I’ve seen 150/152’s, 172 with 12k+ hours, almost guaranteed those were trainers most of their life and have had the crap beat out of them… Logbooks don’t always reflect reality, but a thorough inspection and some forensics of both the books and the plane will generally bring out the good, bad and the ugly. 

[Utah20Gflyer]

I am not an aeronautical engineer but my take on it is calenders age doesn't matter much yet, its more of an issue of avoiding corrosion and the number of hours the airframe has actually been flown.  My understanding is that aluminum fatigues from being flexed repeatedly - a function of the total time on the airframe.  So if you have a Mooney from the 60s like mine with 3440 TT and no corrosion to speak of it should last a very long time.   If you were looking at an airframe from the 60s with 20k TT then that could be of concern, but most Mooney's are owner flown and therefore rack up total time rather slowly.  You don't see many with more than 6k TT.  

So to answer your question, find a plane that has no corrosion and reasonable total time and in 20 years it should be just fine.  

[hammdo]

Mine has 7500+ hours, all owner flown. Airframe is in fine shape. It's been treated many times with corrosion preventive. SB 208 checked several times. All about maintenance. Probably one of the higher times airframes out there and she flys great. David ( @Sabremech) did a ton of updates/upgrades when he had her and it's really made a difference.

I'll fly her as long as I can - and take care of her...

-Don

[Mooneymite]

7 hours ago, A64Pilot said:

However it’s just one of many factors that are important. How it was kept, where it was kept, airframe hours, was it ever a training aircraft, was it substantially damaged in the past and if so was it correctly repaired etc.

I agree with this!  

I'll take a high hour older airplane that has been hangared all it's life over a low time newer airframe that has been a ramp rat all its life.

I don't know if a formula has ever been figured out, but I'm guessing 1 year tied down on the ramp near the ocean = 10 years in a nice, dry hangar. 

Maybe that's conservative?  

How does one verify hangar history of an aircraft?  That's the tough part.  

[A64Pilot]

16 minutes ago, Mooneymite said:

 

How does one verify hangar history of an aircraft?  That's the tough part.  

Every now and again you see a for sale ad showing the airplane tied down, then listing all the covers it comes with and says “always hangared”

I figure if I ever sell mine, I’ll be sure to take a picture of the hangar

Mine concerns me a little as I know it came from or at least spent significant time in Louisiana, and the ash trays are rusted, only tube rust I found was light and right at the pilots eyeball vent. From the missing paint on the leading edges I know she has spent significant time in the rain and guess that’s where the rusted tube under the panel came from, rain through the eyeball vent.

Ash trays tell me that the cabin has had high humidity often.

I’ve seen hangars that I guess weren’t well drained even several days  after the rain the floor was still wet, so not all hangars are equal.

Calender time matters as it takes time for corrosion to occur, all aircraft over a few years old have corrosion, just maybe so slight as to not matter,but it’s like an old man, we all have plaque on our arteries, some just don’t have enough to matter is all.

Edited March 13, 2022 by A64Pilot

[cujet]

Aluminum generally does not, by itself, weaken over time. Properly stored aircraft aluminum sheet metal will have the same characteristics as new. 

Aluminum will weaken/fail with repeated high stress cycles. Obviously, bending a sheet metal part back and forth repeatedly, will cause cracking and eventual failure. This is not what happens when much lower loads are placed on parts. A Mooney wing might handle 10G, so 2G or even 3G's of turbulence is not stressing the part significantly. The wing is therefore able to handle millions of such low-stress cycles without trouble. Think of an airliner wing, the often turbulent conditions, and the 60,000+ hour lifespan. 

The Mooney 4130 steel airframe is, for our discussions, not much different. It is able to handle repeated minor stresses without any degradation or loss in strength. It is also repairable, by the simple act of welding in a new section. 

However, just about any aircraft sheet metal tech will tell you that various aluminum parts will crack due to any number of reasons, including vibration, repeated overload stress, overtemperature, corrosion and so on. The good news is that one can keep an aircraft flying nearly forever with good maintenance. 

[Mooneymite]

1 hour ago, A64Pilot said:

Ash trays tell me that the cabin has had high humidity often.

Rusty ashtrays?

Now there's a deal breaker for sure!  

Little things can sometimes tell big stories.....

[Trow28]

Just look at the ashtrays, they'll tell you all you need to know, got it!

Really awesome information all, I feel a lot better about looking at 50+ year old planes.  A64, if I end up finding something in Florida I'm calling you for my pre-buy.

[ArtVandelay]

Age doesn’t bother me as much hours, I’ve seen 150/152’s, 172 with 12k+ hours, almost guaranteed those were trainers most of their life and have had the crap beat out of them… Logbooks don’t always reflect reality, but a thorough inspection and some forensics of both the books and the plane will generally bring out the good, bad and the ugly. 

Here’s a J that was a trainer…

https://www.controller.com/listing/for-sale/201673285/1991-mooney-m20j-201-piston-single-aircraft

[aviatoreb]

I once saw a J for sale on comptroller that was an Embry riddle plane and it had well over 12,000 hrs on it. It looked good from the pictures.  More important, I trust that the crack A&P team would not be allowing it on their flight line at 11,000 hrs for another 1,000 hrs if there was a worry, nor would they sell it as a working plane rather than parts at 12,000.

Aren't there a bunch of DC3's out there with several hundred thousand hours on them.  Built in the 1930s and still going?

I think things do wear out, but things replaced, maintained, etc and quibbling over 4 or 5 or 6 k alone is not a big deal in my book.

[A64Pilot]

8 hours ago, Trow28 said:

Just look at the ashtrays, they'll tell you all you need to know, got it!

Really awesome information all, I feel a lot better about looking at 50+ year old planes.  A64, if I end up finding something in Florida I'm calling you for my pre-buy.

I’ll maybe help you decide to keep going or to continue, but I’m not experienced enough on Mooney specific issues to be your guy for a pre-buy.

‘Someone who is, will go directly to the problem areas because they know where they are, I don’t, that comes from experience that I don’t have

[A64Pilot]

4 hours ago, ArtVandelay said:

Here’s a J that was a trainer…

https://www.controller.com/listing/for-sale/201673285/1991-mooney-m20j-201-piston-single-aircraft

We had 2 “AT’s” where I went to school, while they weren’t beat to death, they did accumulate probably 7 or eight times as many gear cycles and landings, to say nothing of very many emergency gear extensions, they were flown pretty much daily. The school didn’t allow them off pavement, but the lower gear doors had been removed. Made me wonder if that didn’t reduce the aerodynamic loading on the gear? Why did they remove the lower doors?

The school also wouldn’t let you get gear before flaps under the theory almost all aircraft get approach flaps first and they didn’t want to teach airframe specific. I still won’t drop gear until the white arc, thinking it might be kinder on “things”, once you get used to it, it’s not a hassle just start slowing down further out.

[Kmac]

There are many vintage Bonanza's from the late 1940's still flying today.  If they are still flying in 5 years that is about how old your potential Mooney will be when you are planning on selling.  I would expect you can still make a forever plane from any metal Mooney...

[Will.iam]

KC 135 tankers were originally only supposed to be 60 year before they will be replaced with something better. AF started flying them in 1956 and are still flying them in 2022 and projected to phase out by 2030, so much for 60 years. And replacement was not because of metal fatigue as is about parts availability that even with 396 still flying is becoming to expensive to replace as most are having to be made by third party as Boeing has long stopped making those parts. Boeing now has a life limit on newer airframes but I think that is more of a marketing ploy to sell new aircraft as the DC-8 had no life limit on it’s certificate. As long as you replaced worn parts that thing could fly forever.  When Boeing offered a sweet deal to UPS for their 40 DC-8 they had to exchange to B-757, UPS had to give them their old DC-8’s which Boeing crushed so that no one else could buy them for spare parts and keep their DC-8’s going. It worked as our company only a few years later was forced to switch to the B-757 due to parts becoming scarce / too expensive to procure. 
I think the biggest marketing scam on expiration dates is bottled water. Damn water has been here before man even existed, I’m sure that bottled water will still be good long after the expiration date on the plastic has faded away. 

[Mooneymite]

8 minutes ago, Will.iam said:

 
I think the biggest marketing scam on expiration dates is bottled water. 

Mmmmm.  I dunno.  I think Frank Robinson may have a better scam on his life-limited helicopters!

[MikeOH]

1 hour ago, bluehighwayflyer said:

Ha!  I’ve always thought that bottled water was a scam in and of itself.  

Pass the garden hose!

[DCarlton]

Related...  Is is any harder to get parts for one of the last J's made in 97 or 98 (less than 40 total) than it is to get parts for an F made in the mid-60s during Mooney's high production periods?  Folks are parting our F's now.  Seriously.  Any issues get parts for the newest ones with much smaller production runs?  I may "want" one at some point and that's the only thing I'm concerned about.  Parts. 

[A64Pilot]

16 hours ago, Mooneymite said:

Mmmmm.  I dunno.  I think Frank Robinson may have a better scam on his life-limited helicopters!

I don’t know what the life limit is, but pretty much everything on a helicopter is life limited.

The FAA heavily pushes life limits, and FAR 23 may require it?

I was a presenter at a symposium about spar cap life limits on AG aircraft years ago in Calif.

It was us, our competitor and the FAA, the FAA was presenting everything fatigues and must be replaced based on cycles, our competitor agreed. I disagreed and asked what the life limit cycle wise on a C-172’s wing spar was. A 172’s wing being externally braced is outside of the fatigue cycle, meaning it’s not fatigued, anymore than if I handed you a railroad spike and asked you to bend it back and forth by hand until it broke, your not strong enough to fatigue the spike, any force you can apply isn’t enough.

Old spar cap life limit on a Thrush has been established by failures to be 5,400 hours, with a large scatter factor. New since 2002 spar cap life limit was established by analysis to be 29,000 hours, ( 7 to 1 scatter) We instrumented an S2R-H80 and I flew it to its Certified limits and we raised it to 40,000 hours based on data from the test flights. In truth we discovered that the new spar cap forces are outside the fatigue cycle and it’s not accumulating any fatigue, but to keep from it being a hard fight with the FAA that really wants life limits we accepted the 40,000 limit.

We also established that at max gross as long as you stay at or below VNE you can’t over G the wing, it will stall first.

Ever seen a 40,000 hour GA aircraft? Me neither. So 40,000 hours may as well be not life limited, but we had to have number, they weren’t going to allow on condition.

Edited March 16, 2022 by A64Pilot

[carusoam]

On 3/16/2022 at 1:34 AM, DCarlton said:

Related...  Is is any harder to get parts for one of the last J's made in 97 or 98 (less than 40 total) than it is to get parts for an F made in the mid-60s during Mooney's high production periods?  Folks are parting our F's now.  Seriously.  Any issues get parts for the newest ones with much smaller production runs?  I may "want" one at some point and that's the only thing I'm concerned about.  Parts. 

Buying new parts…. All come from the same very expensive factory….

Buying pre-flown parts… depends on the number of similar airframes sitting in a scrap yard somewhere….

 

Don’t bend anything important…

Best regards,

-a-