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  #31  
Old 01-25-2012, 08:53 PM
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Neal@F14 Neal@F14 is offline
 
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Quote:
Originally Posted by smokyray View Post
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.
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  #32  
Old 01-25-2012, 09:03 PM
Sig600 Sig600 is offline
 
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Quote:
Originally Posted by Neal@F14 View Post
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.
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Last edited by rv6rick : 01-25-2012 at 09:06 PM. Reason: removed expletive
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  #33  
Old 01-25-2012, 09:32 PM
Captain Avgas Captain Avgas is offline
 
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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.

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Last edited by Captain Avgas : 01-25-2012 at 10:00 PM.
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  #34  
Old 01-25-2012, 11:23 PM
LarryT LarryT is offline
 
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Default 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!

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  #35  
Old 01-26-2012, 12:23 AM
Mounz Mounz is offline
 
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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.
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  #36  
Old 01-26-2012, 07:22 AM
Danny7 Danny7 is offline
 
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Quote:
Originally Posted by Captain Avgas View Post
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?

Quote:
Originally Posted by Captain Avgas View Post
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

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
http://www.vansairforce.com/communit...ad.php?t=81170
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Last edited by Danny7 : 01-26-2012 at 07:35 AM.
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  #37  
Old 01-27-2012, 06:20 AM
n38139 n38139 is offline
 
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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 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....
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  #38  
Old 01-27-2012, 08:02 AM
rvaitor87 rvaitor87 is offline
 
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Default 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. 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.
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  #39  
Old 01-27-2012, 10:22 AM
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Bob Kuykendall Bob Kuykendall is offline
 
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Quote:
Originally Posted by cbkillion View Post
...I know I don't have the tools to set those fatty rivets.
A trip to Harbor Freight would fix that!

No, really!

Edited to add: http://www.matronics.com/rv-list/hovan/tips/spar.html

Thanks, Bob K.
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Last edited by Bob Kuykendall : 01-27-2012 at 10:30 AM.
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  #40  
Old 01-27-2012, 10:35 AM
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Quote:
Originally Posted by LarryT View Post

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?
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