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Service Life of an RV?

n38139

Well Known Member
I am in the market for an RV and have taken a look at a couple of higher time airplanes, close to 2000 hours.

Is there any discussion that anybody knows about on the issue of useful service life on an experimental or RV? I tried to talk to a guy a Vans about this but he was avoiding the answer (I understand liability) so does anybody know if there is a design limit or service limit? I am trying to avoid the answer of : "If you take care of it, it will last forever".

thanks
 
Very good question. As we get more airplanes up there in hours we will need to know what to expect. It would be great for some one (or two) to put together a list of things to inspect at different time intervals based on what they may be seeing on their conditional inspections.
 
There are many RV's out there with 3500-4500 hrs still performing as they did day one. Look for the quality in the build and buy one. :)
 
Nobody knows the answer to that because they haven't been around long enough. There are many, many single engine certified airplanes flying around with over 10,000 hours. RV's are built to the same standards (at a minimum) in terms of meterial strength, giving something back in stability for the sake of performance, but with superior materials. If the airplane has lived in a salty environement, take a good look at corrosion. If it's been primed inside, don't worry about it. The engine and everything else is time-limited and can be overhauled or replaced. Check service bulletins and also any AD's on certified components and let your conscience be your guide....
 
There are many, many single engine certified airplanes flying around with over 10,000 hours.

I did my float rating on a 172 that had just shy of 40 000hrs. I'm sure it's over by now. 99% of that time is on floats or skiis. A life of landing on waves and snowmobile tracks is a lot harder on the airframe than paved runways.
 
I am trying to avoid the answer of : "If you take care of it, it will last forever". thanks

First of all I don't believe a 2000 hour RV is "high time"- I would say that is well proven.
Some cracking may be found in some weak spots such as landing gear and empennage. Also some airframe details may need attention over time such as the canopy and cowl. I believe there are many models that are built with better corrosion proofing than my 1961 182.

But you already know the answer to your question- You can't avoid that answer because it has a lot of truth to it!:D
 
DC3 C47

DC3 and C47 are not pressurized and built the same as our RV kit planes. Some DC3s have 50,000 hours.
Our RVs will last the same hours if the time life items are taken care of.

A cowl can replaced, enging mounts can be repaired or replaced. RVs do not have hardly any issues with the airframe. The design is well thought out and I expect some will get some really high times. Almost wish I had to fly to work and get several hundred hours every year. Like some So Cal RVrs do
 
Service life of a Cherokee 140 wing (one that has not seen "severe duty") is around 60,000 hours, if it hasn't corroded to powder by then. Heck, even a Traumahawk gets 10K hours. I'd like to think that a well-built RV ought to last at least as long as a T-hawk :D
 
Service life of a Cherokee 140 wing (one that has not seen "severe duty") is around 60,000 hours, if it hasn't corroded to powder by then. Heck, even a Traumahawk gets 10K hours. I'd like to think that a well-built RV ought to last at least as long as a T-hawk :D

Only if it was primed correctly.

I kid, I kid.....
 
Service life of a Cherokee 140 wing (one that has not seen "severe duty") is around 60,000 hours, if it hasn't corroded to powder by then. Heck, even a Traumahawk gets 10K hours. I'd like to think that a well-built RV ought to last at least as long as a T-hawk :D

Don't confuse certification standards with real life. The Cherokee was certified under regulations which didn't require a stated service life. The Tomahawk was one of the first light aircraft certified after the FAA mandated a service life. No telling what an apples to apples comparison would say.

One thing I remember from the RVator a long time ago was that the RV-6 wing is so over built it could withstand something like 12,000 hours of continuous use at its aerobatic limit - 6 G's. That's a strong wing.

Van's commentary on structural issues has been a little more reserved in recent years. ;-)
 
Some DC3s have 50,000 hours.
Our RVs will last the same hours if the time life items are taken care of.

Vans claims that the life of the anodised wing spar in the current models is 12,000 hours. They claim that the anodising provides superior corrosion protection but halves the life of the spar. Presumably they didn't feel comfortable leaving the corrosion protection of such a critical component as the wing spar up to the builder as they did in earlier models (and with good justification if you read the primer war archives). The trade-off is a shortened spar life.

Many people would argue that when the wing spar needs replacing the average aircraft is at the end of its PRACTICAL life. Of course you can keep rebuilding parts of an aircraft forever (think warbirds) but there comes a time when that process no longer makes dollar sense for the average aircraft.
 
Vans claims that the life of the anodised wing spar in the current models is 12,000 hours. They claim that the anodising provides superior corrosion protection but halves the life of the spar. Presumably they didn't feel comfortable leaving the corrosion protection of such a critical component as the wing spar up to the builder as they did in earlier models (and with good justification if you read the primer war archives). The trade-off is a shortened spar life.

Many people would argue that when the wing spar needs replacing the average aircraft is at the end of its PRACTICAL life. Of course you can keep rebuilding parts of an aircraft forever (think warbirds) but there comes a time when that process no longer makes dollar sense for the average aircraft.

I have never heard of anyone advocating against corrosion-proofing the wing spar of the legacy built-up spar kits.
 
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Some DC3s have 50,000 hours

I got my DC-3 type rating in one that had 85,000 hrs on it at the time. When it reached 100,000 hrs., it was parted out because it was operating on a 121 certificate at the time (39 years ago) at that was the limit for 121, then. But it was still a good viable airplane. If you maintain an aircraft well, it will last your lifetime.
 
Vans claims that the life of the anodised wing spar in the current models is 12,000 hours. They claim that the anodising provides superior corrosion protection but halves the life of the spar. Presumably they didn't feel comfortable leaving the corrosion protection of such a critical component as the wing spar up to the builder as they did in earlier models (and with good justification if you read the primer war archives). The trade-off is a shortened spar life.

Many people would argue that when the wing spar needs replacing the average aircraft is at the end of its PRACTICAL life. Of course you can keep rebuilding parts of an aircraft forever (think warbirds) but there comes a time when that process no longer makes dollar sense for the average aircraft.

20-years ago, I heard that your 12K hours was 10K. Everything else was the same.
 
Vans claims that the life of the anodised wing spar in the current models is 12,000 hours.

Curiosity question....I understand the basics of fatigue (SN, stress ratio, etc), but little of the assumptions used to establish a service limit in hours. For example, does the designer assume the maximum gross weight or some fraction of it? Is the assumed load entirely positive, and is there some standard for cycles per hour?

My question is general in nature. I would not ask our resident engineers for specific comment on the Van's spar.
 
I have never heard of anyone advocating against corrosion-proofing the wing spar of the legacy built-up spar kits.

Quite true Sam, but a bit of a read through the primer wars archives will quickly reveal that in the Experimental category "corrosion-proofing" can mean just about anything. For some it can mean just alodining, for others it's a quick spray with a rattle can. In the Experimental category there is just no bottom line because everything is at the final discretion of the individual builder. With this in mind I think we can assume that Vans ultimately came to the conclusion that the spar was such a critical structural component that it was in their interests (and in the interests of lazy or incompetent builders) to supply the spars professionally anodized and assembled straight from the factory.
 
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If you've never seen the spar on a C-172/182... it's pretty eye opening.

I toured the assembly line a bunch of years ago picking up a new 172 at the factory, and they had these things stacked up hanging off of ONE nail on the wall. I would be surprised if the whole thing was more than a few pounds. There are plenty of 172's out there with 10's of thousands of student pilot hours on them soldiering on. By comparising the RV spar is ENORMOUS. If there is a weak link I would think it's the corrosion of the actual bolts themselves... that's an easy fix.

IMO, a well cared for RV will probably go 30-40K hours no problems.

Cessna spar for comparison, this things is as light and flimsy as a wing rib, yet I've never heard of an inflight breakup.

sparm.jpg
 
Quite true Sam, but a bit of a read through the primer wars archives will quickly reveal that in the Experimental category "corrosion-proofing" can mean just about anything. For some it can mean just alodining, for others it's a quick spray with a rattle can. In the Experimental category there is just no bottom line because everything is at the final discretion of the individual builder. With this in mind I think we can assume that Vans ultimately came to the conclusion that the spar was such a critical structural component that it was in their interests (and in the interests of lazy or incompetent builders) to supply the spars professionally anodized and assembled straight from the factory.

I would be more inclined to believe the delivery of an assembled and finished spar had more to do with economics and the spar not being as well suited for amateur assembly as the old design.

There are many aspects of the kit that could be mangled by "lazy or incompetent builders" that would have as much or more impact on safety as a poorly assembled spar. Including lazy and incompetent builders in Vans assessment of their kits is probably a stretch, and I have never heard or seen any indication that Vans has attempted to fool-proof their designs. Kit enhancements appear to always be directed toward decreasing build time for the builder and decreasing inventory for Vans.
 
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While I still had my Ercoupe and the RV12 wing was under construction, I could not help but compare the 65 year old Ercoupe wing to the RV12. Made me wonder how the Ercoupe had ever stood up with 65 years of use and abuse.
If you've never seen the spar on a C-172/182... it's pretty eye opening.

I toured the assembly line a bunch of years ago picking up a new 172 at the factory, and they had these things stacked up hanging off of ONE nail on the wall. I would be surprised if the whole thing was more than a few pounds. There are plenty of 172's out there with 10's of thousands of student pilot hours on them soldiering on. By comparising the RV spar is ENORMOUS. If there is a weak link I would think it's the corrosion of the actual bolts themselves... that's an easy fix.

IMO, a well cared for RV will probably go 30-40K hours no problems.

Cessna spar for comparison, this things is as light and flimsy as a wing rib, yet I've never heard of an inflight breakup.

sparm.jpg
 
If you've never seen the spar on a C-172/182... it's pretty eye opening.

I toured the assembly line a bunch of years ago picking up a new 172 at the factory, and they had these things stacked up hanging off of ONE nail on the wall. I would be surprised if the whole thing was more than a few pounds. There are plenty of 172's out there with 10's of thousands of student pilot hours on them soldiering on. By comparising the RV spar is ENORMOUS. If there is a weak link I would think it's the corrosion of the actual bolts themselves... that's an easy fix.

IMO, a well cared for RV will probably go 30-40K hours no problems.

Cessna spar for comparison, this things is as light and flimsy as a wing rib, yet I've never heard of an inflight breakup.

With all due respect I don't think that the spar comparison is relevant. The Cessna wing is a braced design whereas the RV wing is cantilevered. Big difference.

Incidentally it is relevant that in 2003 Gus Funnell at Vans stated that the factory was assuming that anodizing would cut the fatigue life of the RV spar in half (down from 24000 to 12000 hours), but that they took this course because they were concerned that RV spars with lesser protection would suffer from corrosion long before reaching the 12000 hour fatigue limit of the anodized spars.
 
Time will tell.

Curiosity question....I understand the basics of fatigue (SN, stress ratio, etc), but little of the assumptions used to establish a service limit in hours. For example, does the designer assume the maximum gross weight or some fraction of it? Is the assumed load entirely positive, and is there some standard for cycles per hour?

My question is general in nature. I would not ask our resident engineers for specific comment on the Van's spar.

Dan, my Air Tractor 502 has a steel spar CAP life of 8,000 hours. This came about after a 602 shed a wing in Arizona and killed the pilot. Our spars don't touch in the middle either but unlike the -7's 8's and 9's are about 18" apart with 4 upper and lower steel caps tying it all together.

An emergency AD note was issued and within three days, two more Air Tractors were found, during annual inspection, to have severely cracked lower spar caps..potentially fateful shortly.

At the time, there was no time life for them. All of the bending that our wings go through, told the tale, even though Leland Snow had sandbagged them to destruction, prior to the first airplane delivery.

Fatigue is so difficult to quantify, by his admission, that we do the best that we can do....and I suspect that'll likely be true with the RV's.

Best,
 
I would be more inclined to believe the delivery of an assembled and finished spar had more to do with economics and the spar not being as well suited for amateur assembly as the old design.

It seems to be your contention that Vans supplies the current spar in a fully fabricated state because they believe it is "not well suited for amateur assembly".

I have suggested that Vans supplies the current spar in a fully fabricated state because they do not have confidence that all builders will do a professional job.

Sam, semantics aside, surely we are saying the same thing.
 
With all due respect I don't think that the spar comparison is relevant. The Cessna wing is a braced design whereas the RV wing is cantilevered. Big difference.

The Captain is right, but hey, you could have a spar like that in an RV, it just needs a slight modification. Google Cessna 188 for inspiration :rolleyes:

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
The C-172 wing spar doesn't see much bending because of the strut, this will allow the spar to look much flimsier than a RV spar. But the RV spar is pretty strong. If installed properly, I don't see the spar will ever fail before something else.

If you've never seen the spar on a C-172/182... it's pretty eye opening.

I toured the assembly line a bunch of years ago picking up a new 172 at the factory, and they had these things stacked up hanging off of ONE nail on the wall. I would be surprised if the whole thing was more than a few pounds. There are plenty of 172's out there with 10's of thousands of student pilot hours on them soldiering on. By comparising the RV spar is ENORMOUS. If there is a weak link I would think it's the corrosion of the actual bolts themselves... that's an easy fix.

IMO, a well cared for RV will probably go 30-40K hours no problems.

Cessna spar for comparison, this things is as light and flimsy as a wing rib, yet I've never heard of an inflight breakup.

sparm.jpg
 
Ah, the life of RV's..

Steve,

There are alot of very intelligent folks (Vans Aircraft included) working on the design end of airplanes and looking at design strengths/weaknesses with service life being one of the equations. Elasticity is yet another. Aluminum isn't elastic, you stress it and it bends, too many times and it breaks. Stress is cumulative.

Many years ago while I was building my 4 I heard the urban legend of the new RV-6 (then) wing structure ultimate load test. Needless to say they piled sandbags until 150% of ultimate load (9G's) and the inspector left the building. The legend states that the few remaining employees were instructed to "pile on" until absolute failure. It never actually broke but popped rivets and distorted to the point of "represented failure". What that number was has been a closely held secret all these years. I heard it was in the neighborhood of 12 G's. Pretty impressive.

Having routinely put 9G's on an airframe for 20 years and seen the "fixes" for spar cracks over the years (which look like boiler plate riveted onto the structure), I can attest to the strain. The 20+ year old F16 airframes are approaching 8000 hours with no end in sight. Few airframes endure the abuse of those 2 little 18" wings. MAF flies their missionary Cessna 206's to 12,000 hours before retiring them. Their 206's work harder than any out there.
As far as the highest produced airframe in history, as Sig mentioned (the C-172) there has never been a documented in-flight structural failure. One was recently retired with 30,000 hours. http://www.pprune.org/caribbean-latin-america/306333-30-000-hour-cessna-172-a.html
Again, very impressive.

As mentioned above, the service life of aluminum is directly proportionate to the care and feeding thereof.

Smokey
www.fly-4-life.com
 
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It seems to be your contention that Vans supplies the current spar in a fully fabricated state because they believe it is "not well suited for amateur assembly".

I have suggested that Vans supplies the current spar in a fully fabricated state because they do not have confidence that all builders will do a professional job.

Sam, semantics aside, surely we are saying the same thing.

No, we aren't.....even though it probably doesn't matter.

The point I was trying to make is that it may be more expedient from a manufacturing process to build all the spars in house since QB spars have to be assembled. There aren't nearly as many parts in the new spars as the old so it may be more cost effective to assemble all spars regardless of whether they are going into a standard or quick build kit. In that way they would be better suited for Vans assembly rather than "amateur" assembly.

You have stated that Vans is afraid there are too many lazy and incompetent builders out there to risk having unassembled spars leave the factory. I do not agree with that position and I have no reason to believe Vans holds that view.
 
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time

If I were looking for a used RV I would be more concerned with age than time in flight. In fact, if the bird wasn't flown enough (50-100 hrs / yr) I would be less interested.

The airframe (if hangared) is not a concern. There have been some problem points, such as cracks in the steps and engine mounts, baffle errosion, exhaust stringers etc. to check on. But those are all items that can be dealt with.

One thing I would look for (in the A models) is for the new style nosewheel fork.

A detailed (nit-picky) inspection should identify any questionable parts or elements.

I have seen and compared the construction of RV's vs. production airplanes
(Cessna, Piper) and would trust my life to an RV any day, even one with lots of hours.:)
 
life limted parts?..not just airframes?

Very good question. As we get more airplanes up there in hours we will need to know what to expect. It would be great for some one (or two) to put together a list of things to inspect at different time intervals based on what they may be seeing on their conditional inspections.

Yeah, what Phil said....what things get replaced at 100 hours, or 2 years, whichever comes first?
Alternator belts? aluminum brke lines? Primer lines? Plastic MP hoses? Exhaust pipes?......
of course, most of us do the IRAN type maintenance, but if I'm not an AME/ A&P guy, how the heck do I know what a 'good' intake runner hose connection looks like?

Sure would be nice at annual time to have a reference to go to! :)
 
As far as the highest produced airframe in history, as Sig mentioned (the C-172) there has never been a documented in-flight structural failure.

Back about ten years ago, when I was still a freshly-minted pilot with my first airplane, I flew my Cherokee to a fly-in in Illinois where one of the oldtimers there told a tale of a student pilot and his CFI in a C172 that suffered an inflight failure of one of the lift struts due to massive corrosion inside the strut. The oldtimer (quite possibly the CFI in the story) said the wing never folded upwards completely, and they successfully landed the thing with a big dihedral on the affected wing and undergarments needing changing. I dunno how true the story was... as there was a fair amount of ethanol consumed and yarns were being spun that night, but it sure was an interesting tale.
 
Back about ten years ago, when I was still a freshly-minted pilot with my first airplane, I flew my Cherokee to a fly-in in Illinois where one of the oldtimers there told a tale of a student pilot and his CFI in a C172 that suffered an inflight failure of one of the lift struts due to massive corrosion inside the strut. The oldtimer (quite possibly the CFI in the story) said the wing never folded upwards completely, and they successfully landed the thing with a big dihedral on the affected wing and undergarments needing changing. I dunno how true the story was... as there was a fair amount of ethanol consumed and yarns were being spun that night, but it sure was an interesting tale.

When I was in college I spent a fair amount of time towing banners up and down the beach.

We had one plane that would make this odd "popping" sound when the banner was picked up and you made the aggressive pull up for altitude. It was a worn out C-172 with a STOL kit.

Our mechanic did an annual on it and found that the carry through spar in the horizontal stab had broken clean through. The popping noise was the two ends of the spar catching on each other as it flexed up and down. I almost near had a heart attack... but that thing kept right on trucking in that condidtion up until we found that. :eek:
 
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This thread started as a direct question about the possible service life of an RV. Apart from the fact that Vans puts a fatigue service life of 12,000 hours on the anodized RV wing spar (it's "on condition" after that) this question can never be really answered.

For a start it would be erroneous to lump all of the RV models together. It's my guess that the non-aerobatic models such as the RV9(A) and the RV10 could see a longer average service life than the aerobatic models. And the RV12 with it's pop rivetted construction is in a category of its own.

However in my opinion, the service life of any individual RV aircraft will be determined not by the quality of the design (which is pretty good), but by the quality of the initial construction and the quality of the ongoing maintenance. And my observations are that the quality of the construction and the quality of the maintenance in the Experimental category varies enormously because it is left entirely to the discretion of the individual and without any checking system. And so you can get showstoppers and bottom-of-the-barrel shockers being produced by the same system.

And if any of us are in any doubt as to how deep the bottom of the barrel can be we need only refer to the attached photo of the infamous spar that was ground back because it "would not fit".

In reality I suspect very few RVs will ever reach Vans 12000 hour spar fatigue limit. That's many decades of flying for the average RV and the truth is that most builders are building with their focus on their own limited flying future, and not the aircraft's extended flying future in the hands of subsequent owners. It's hard to convince some-one that they should be spending months priming their RV with BMS10-11 so that it will last for 50 years....particularly if they're 60 years old. :D

 
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Some numbers

12,000 x 180mph = 2,160,000 statute miles = 85+ circumnavigations of the earth.

12,000 x $50/hr. for av gas = $600,000

I believe that Turbo's RV has the highest time of any privately held Van's aircraft. Rosie may be next. At the rate they put on hours it will take 30 years to accumulate 12,000 hours.

At the rate most of us fly, it would take 120 - 240 years to accumulate that time.

Personally if I had $600,000 and a paid off mortgage, I would retire and try to spend it on flying!

Larry Tompkins
N544WB -6A purchased flying
W52 Battle Ground WA
 
I can confirm the spar life discussion as it appeared in the 12/91 edition of the RVator. To quote the article: " For our calculations, we used loading cycles which a military trainer would experience".
Further reductions to the life were applied to allow for any variables before the 12K spar life was arrived at. Vans sells a book called 27 years of the RVator and a wealth of information is contained in these volumes. I believe it is a must read for anyone buying an RV as it allows you to assimilsate some very essential knowledge you have missed out on by not building one. A good example is how to land a nose gear RV. I believe an alarmingly large percentage of nose gear drivers who experienced nose gear failure and ended up on their backs had not built these aircraft themselves.
Van likes to speak of "real world" facts and figures. I would say that anyone purchasing a well built and maintained RV with two thousand hours will enjoy a lifetime of flying in "real world" terms.
 
And if any of us are in any doubt as to how deep the bottom of the barrel can be we need only refer to the attached photo of the infamous spar that was ground back because it "would not fit".

which was really far away from ever being put into a flying airplane...

Are there some better examples out there of Flying assembly/ construction problems?

OK, let's now turn the page and look at the average first-time RV builder. This person may typically be an IT specialist who would struggle to change the oil in his car and probably doesn't know the difference between a pushrod and a conrod. He's now embarking on the task of designing and installing a complete FWF set-up, and if that's not daunting enough he may even be contemplating doing an auto-conversion to boot. He may have started out not knowing the difference between a volt and an amp but now he's also designing his own electrical architecture. And all the while he's learning as he goes along by using his aircraft project as a test bed to practice on.

there is such a thing as an average first-time RV builder? He is typically an IT specialist?!?!

I disagree strongly. It is my experience that there is almost no work category that an RV builder would "typically" be. We have professionals of any sort here on VAF, and I think there are as many people that for whatever reason are not inclined to spend their valuable time posting on VAF telling how they are deburring or priming their tail kit.. The variety of careers is nothing short of astounding to me.

What I do notice as a trend is that the people that finish more than a couple kits are dedicated, persevere, are able to learn, are relatively skilled with their hands (or able to become that way) and "typically" have much better planning ability than me :D

edit: would like to reference the "day job" thread as one example of the variety of careers and people doing a professional job 40+ hours a day and still making time to build a plane in their "spare" time :D
http://www.vansairforce.com/community/showthread.php?t=81170
 
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Thanks for all of the inputs. This thread wandered all over the place but at least I have been sufficiently scared :cool: not to buy another RV although I never worried about my other two. I guess I will just keep my 13,521 hour flown by the US Army, Birddog. It was built by professionals and it was maintained by 18 to 22 year old trained specialist....:D
 
22 years,,,,

Thats how long my -3 has been flying. no major problems, just the minor stuff. I would hop in it tomorrow and fly to California, if I knew someone there.:D The point is, as long as you build it right, take the time to prime, there is no reason why it shouldn't last as long as you do.:eek:
 
I believe that Turbo's RV has the highest time of any privately held Van's aircraft. Rosie may be next. At the rate they put on hours it will take 30 years to accumulate 12,000 hours.


Larry Tompkins
N544WB -6A purchased flying
W52 Battle Ground WA

looks like rosie and need to stay healthy for the next 30 years.

were are we going next?
img08770.jpg
 
Service Life

What I'm getting from this is that, failing flight into cumulo granite, I'll reach my expiration date long before my airplane will.
 
Service Life

The question of service life is an excellent one, and one which I reckon is not helped by the war stories of guys flying aircraft with 50 000 hr+ airframes. Fact is aluminum cracks under conditions of cyclic loading, and therefore our aluminum RV airframes have areas that we should be paying attention to during annual condition inspections (particularly high cycle and high time RV?s).

Service life is a difficult question. There are no safe-life estimates for an RV that I?m aware of. Vans may have tested a wing spar to 12000 hrs. This means little without knowing the details such as spar type, spar material, load spectrum, workmanship, etc. Also, the wing spar is by no means the only item one should be concerned about.

The service life of an RV from a metal fatigue perspective will be dependent on:
A) Basic design and strength of the aircraft (materials, layout, joint configurations, sizing etc)
B) Construction workmanship (maintaining edge distance, hole spacing, drilling or reaming, deburring, sharp edge removal, surface finish, surface treatment, and flaws created by bucking bar mishaps, dropped tools, mis-drilled holes, etc )
C) Loading spectrum (did you fatten your RV with luxuries, do you mostly fly A to B, fly over mountains regularly, do aerobatics, dog-fighting, do you operate on rough fields, is your prop dynamically balanced, is your engine smooth? etc)
D) Ability of the RV community to identify problems, spread the word, and implement on-going repairs.

We will assume Vans did a tremendous job getting A) right with an adequate service life in mind (however nothing is documented, remember these are amateur build ?experimental? aircraft where we as the builders are taking responsibility for our airframes). Now, assuming everybody stuck to the plans, it is likely A) will be similar between similar RV?s. However B) and C) will not. In the amateur world, workmanship and loading spectrum are big variables. Just because someone has reached 4000 hours with no identified problems is not a reason for everybody else to ignore service life, drink scotch, and go on pulling 6G.

Regarding D), as the RV fleet gathers more cycles and hours, there are going to be some issues that arise. There are several key locations around the airframe that undergo cyclic loading every flight (sometimes many times a flight) such as wing spars, wing carry-through box, horizontal tail spars, vertical tail spars, fuselage longerons, engine mount, landing gear, fittings & back-up fittings etc. Hopefully the trail blazes in our community will take time during annuals and investigate some of these areas. VAF (and Vans hopefully) will be pivotal in making sure the message gets out if something comes up. Waiting for the NTSB and then the FAA to do it is not the way to go. Be vigilant during your annuals.

I for one will perform some basic airframe inspections at annuals, and during any other time when some key locations become more accessible (ie wings come off etc). Also, as the builder I know of some locations where there were some accidental flaws. I will look at those too. I look forward to an airframe that will hopefully deliver thousands of hours of fun.

In response to DanH, yes, commercial aircraft tend to refer to ?cycles? when they design for safe-life (a cycle is usually a Ground to Air to Ground (GAG) mission). A fatigue mission profile is developed whereby the aircraft is at its typical weight, relevant fuel load, doing a typical mission. The structure is then analyzed using this fatigue mission to show it good for its safe-life of XXXXX GAG cycles. In some cases, the structure may also be subjected to ?high cycle? loadings, and in those cases the additional cycles would be included in the calculations.

Robert Grigson
RV-8 FB with IO-375
266 hours and loving it
 
Data point

I know I am just a builder, I hope my experience as a maintainer is of value to someone.
Cessna requires eddy current inspections at different thresholds for the C208B depending on if it is flown in "normal" or "severe" conditions. Structures for the engine, landing gear, wing attach, and stabilizer attach all get looked at. Some inspections require complete removal (stabilizer and strut attach), others require on bolt at a time. These inspections are designed to find cracks using either bolt hole probes or surface probes. One uses a ring probe to look for second layer cracks. Out of all these inspections, the only thing we found was chafing on the vertical stabilizer attach (14,000hrs, 18,000 cycles if I remember right). This required replacing both vertical stab spar webs, and a bulkhead. We found the chafing because it had to come apart for the inspection, not the eddy current inspection itself.
I intend to use close tolerance bolts in reamed holes for the vertical stabilizer attach and start removing to look at it at 3 or 4 thousand hours. This attach area has AD's against it for the C206, C207. Seems to me Bonanza had some trouble in this area to, Can any one chime in? The loading is not symmetrical and doesn't carry all the way through like the horizontal stab.
Doing the one bolt at a time for the wing attach is not so good from a labor, quality of work perspective. If I do (special) wing attach inspections, I would consider x-ray, if it can be done for a couple hundred bucks. A surface probe eddy current might work O.K. (any Level 2 techs have an opinion?), again starting at 3000, or 4000 hrs.
Landing gear and it's mounting seem to let go without catastrophic results, an are being found visually before anything really serious occurs. The interior part of this assembly will likely not be covered in my airplane so I can keep an eye on it. I would like to see a pole on how this area fails, but am not sure how to present the questions. Hours, cycles if tracked, and home airport surface material would be nice to know.
 
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