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Tail cone bulkhead cracks

 
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indigoonlatigo(at)msn.com
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PostPosted: Sun Feb 05, 2006 8:40 pm    Post subject: Tail cone bulkhead cracks Reply with quote

I got started on my tail cone this weekend and I found two of my bulkheads
had cracks in the center bend over flange. This flange metal is not used
for anything except to provide some stiffness to the structure. The F 1010
bulkhead had three cracks in one corner and one that nearly went to the web
of the bulkhead.

I will call Van's tomorrow to find out what they say, but my fealing is that
if you can see the split, there my be more that is there which you can't
see. All cracks are atleast 3mm long and some as wide as 1mm at the start.

Any concensus on this. There is so much concern about inadvertently
scratching aluminum for fear of creating weak point, this seems not
acceptable.

If I have to send them back it will probably cost $25-30 bucks and for
what.

John G. 409


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coop85(at)bellsouth.net
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PostPosted: Mon Feb 06, 2006 4:36 am    Post subject: Tail cone bulkhead cracks Reply with quote

John,
You may want to check the archives on this, I think several folks hade
the same problem and I vaguely remember someone posting Vans' response (I
don't know what it was though)

Marcus

Do not archive

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zackrv8



Joined: 14 Jan 2006
Posts: 133

PostPosted: Mon Feb 06, 2006 5:32 am    Post subject: Re: Tail cone bulkhead cracks Reply with quote

John,

Can you take a close-up picture of the crack and post it?

Zack


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johnwcox(at)pacificnw.com
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PostPosted: Mon Feb 06, 2006 1:37 pm    Post subject: Tail cone bulkhead cracks Reply with quote

A crack is and will continue to be a manifestation of stress. Unless
relieved, it continues to grow. Think of a crack in Plexiglas. Stop
drilling only attempts at a solution. Replacement is always the only
prudent course. Hence the zealous focus on deburring. Nothing will
ever remove a crack, only cosmetic coverup is possible.

Require a non stressed part. To follow the mantra to "Just Build It"
anyway is foolish. This is not as rare as many builders blindly think.

Others should speak up. This is a repeat of the post of a few months
ago.

John - $00.02
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ron.mcgann(at)baesystems.
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PostPosted: Mon Feb 06, 2006 1:58 pm    Post subject: Tail cone bulkhead cracks Reply with quote

John,
I have no problem with anyone erring on the side of caution.  But the cracks in the bulkheads were caused during the manufacturing process.  The stresses that caused the cracks have long been removed.  If the crack is appropriately treated (ie smoothed and relieved), why do you think there would be a continuing problem? 
cheers,
Ron
#187 fuse
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johnwcox(at)pacificnw.com
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PostPosted: Mon Feb 06, 2006 4:49 pm    Post subject: Tail cone bulkhead cracks Reply with quote

Sorry Ron, I don’t agree with the simplification as being just cautious behavior.  We have teams of inspectors at the airline using little Geiger counter like devices, looking for subsurface cracks (non visible cracks) on all of our Air Carrier aircraft (both metal and composite surfaces).  Those are cracks not visible to the naked eye.
 
Home builders would be shocked at the effort spent forth on surface preparation, corrosion removal, crack investigation and remediation.  Anyone selling cracked parts has a cracked customer.  Try convincing a new car purchaser that the cracked windshield or crack in a fender seam is Okay.  Properly executed cutouts, reams, folds and pressed parts are okay they are not cracks.
 
Usually the “to be formed” aluminum is untreated, natural Aluminum Clad (Temper – 0) which after correct forming, is sent to finish which might include various heat treatments and soak times (for a variety of conditions – solution heat, Precipitation Heat or Annealing/ Reheat) and then final assembly.  Then of course there is Strain Hardening (Roto peening).  Any good Structural Repair Manual whether General Aviation, Air Carrier or Owner Built is going to acknowledge a crack is a crack and it defines the loss of the material’s ability to handle stress, tension, compression, bending, torsion and shear.  Loss of ability can not be regained without additional weight of a patch or removal of the errant part. Period.
 
This dog won’t hunt in any color.  You get what you are willing to settle for.  Our standards are just different. Caution has nothing to do with it. Most builders don’t even read the SRM. Cracks are symbolic of the improper handling of the material prior to, during or subsequent to installation.  Had anyone mentioned the poor quality of the composite work lately? As an A & P, there are scores of wives (surviving spouses… PC correct) just waiting to engage attorneys to chase my assets for imprudent advise, incorrect actions or inactions.  23 years as an FAA Pilot Examiner and a current pilot who has lost 8 friends brings me a different cautiousness to the discussion than first time homebuilders.
 
Just go and enjoy the building process.  And John Gonzales, contact me offline for a short list of good books.  Imagine the scenario when you go to sell your cracked aircraft, the new owner must the use an A & P to maintain it (cause he didn’t build it) and the A & P requires the exterior skin be removed so the errant bulkhead can be brought Compliant.  Or I’m hired by the courts as an expert witness to provide testimony that established practices were intentionally ignored by the Owner/Builder.  Do it right once, use common sense or stay on the ground and help keep us flying pilot’s insurance rates lower.
 
If the RV-10s follow the pattern of the Lancairs, Cirrus, Glassairs and Kitfoxes, then with the scores of aircraft coming online in the next two years there is a clear potential for significant insurance claims.  These will come from, Prop Strikes, CFIT and flight into IFR conditions and a host of other pilot induced decisions.  The result is that the surviving pool of builder’s still riveting will get to financially cover those who precede them.
 
John – KUAO
 
PS -Remember the Airworthiness Claim that you are building this aircraft for your education and enjoyment.  Buy a book on SRM and read it.
 
DO NOT ARCHIVE
 

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of McGANN, Ron
Sent: Monday, February 06, 2006 1:57 PM
To: rv10-list(at)matronics.com
Subject: RE: Tail cone bulkhead cracks

 
John,
I have no problem with anyone erring on the side of caution.  But the cracks in the bulkheads were caused during the manufacturing process.  The stresses that caused the cracks have long been removed.  If the crack is appropriately treated (ie smoothed and relieved), why do you think there would be a continuing problem? 
cheers,
Ron
#187 fuse
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ricksked(at)earthlink.net
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PostPosted: Mon Feb 06, 2006 6:44 pm    Post subject: Tail cone bulkhead cracks Reply with quote

Don't feel too bad Ron,
 
I saw the "John Cox light" when I mentioned I was in the process of using regular bolts to hold the center spars together instead of the close tolerance bolts provided in the kit....bottom line was John was right in his answer and is right on track with this response. I combed over my bulkheads after first seeking this post months ago and found nothing wrong. I totally understand your reasoning. If I had found cracks I would rely on Van's to provide the proper fix, I use John to keep my thinking straight on these questions, cause deep down I know he is probably right.
 
Rick S.
40185
Fuselage
 
PS- When can I remove some of those bolts? It is needed to get clearence to rivet the side skins.
 
do not archive


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ron.mcgann(at)baesystems.
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PostPosted: Mon Feb 06, 2006 7:11 pm    Post subject: Tail cone bulkhead cracks Reply with quote

I take no offence.  The question I asked was simple enough. The stresses that caused the crack have been removed.  Why can't the crack be repaired?
 
I agree that Vans should be providing us defect free parts in the kit.  I had a cracked bulkhead, informed Vans, and they promptly replaced it.  None of us (except perhaps John) has built, or will ever build the perfect airplane.  Simple economics prevent us from always replacing any part with the slightest chip, scratch or dent with virgin parts.  Repairs in accordance with accepted practice are a part of the build process.
 
We all take pride in our work and do the best we can based on our backgrounds and innate ability.  These forums are an invaluable source of guidance and inspiration, even if some posts are 'over the top' and verge on the personal.
 
Ron
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indigoonlatigo(at)msn.com
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PostPosted: Mon Feb 06, 2006 7:39 pm    Post subject: Tail cone bulkhead cracks Reply with quote

Ron,

Please do not take it as an insult. Your points are valid and meaningful.
They represent the other side. We need to show all angles of the problem
and I did find your e-mail helpful. There are a lot of factors working here
in building these airplanes, too many to mention. I wish so badly that I
could get 100% results on everything. I even thought about using the first
empennage kit as practice, but I am a still working, no trust fund, have a
daughter and a wife and other commitments in life.

I thank you all and everyone has an opinion which is meaningful to me.

One consideration...simplicity in your panel design will save money for
psychiatric visits...Just kidding.

Thanks,

John G.
[quote]From: "McGANN, Ron" <ron.mcgann(at)baesystems.com>
Reply-To: rv10-list(at)matronics.com
To: <rv10-list(at)matronics.com>
Subject: RE: Tail cone bulkhead cracks
Date: Tue, 7 Feb 2006 13:36:38 +1030

I take no offence. The question I asked was simple enough. The stresses
that caused the crack have been removed. Why can't the crack be repaired?

I agree that Vans should be providing us defect free parts in the kit. I
had a cracked bulkhead, informed Vans, and they promptly replaced it. None
of us (except perhaps John) has built, or will ever build the perfect
airplane. Simple economics prevent us from always replacing any part with
the slightest chip, scratch or dent with virgin parts. Repairs in
accordance with accepted practice are a part of the build process.

We all take pride in our work and do the best we can based on our
backgrounds and innate ability. These forums are an invaluable source of
guidance and inspiration, even if some posts are 'over the top' and verge
on the personal.

Ron

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ricksked(at)earthlink.net
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PostPosted: Mon Feb 06, 2006 7:54 pm    Post subject: Tail cone bulkhead cracks Reply with quote

Until I saw your pictures I would have agreed with the stop drill option, It is OK to do that in some case (don't flame me, look at all the spam cans, F-4's and B-52's, with stop drilled cracks) but the location of those crack indicate the material was stretched until it tore. I think there may be more distress than meets the eye. Good call to replace the part.

Rick S.
40185
Fuselage


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jjessen(at)rcn.com
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PostPosted: Mon Feb 06, 2006 7:57 pm    Post subject: Tail cone bulkhead cracks Reply with quote

I find it disconcerting that we are told in the manual to deburr out little hearts out because a crack can form from the most benign little file or shear mark, then when a part is shipped with cracks (why was it not inspected for the cracks to begin with and replaced before shipment?) the attitude is that it's not a big deal, drill a hole, sand it out and just build it (I, too, have been told to "don't worry, just build it.).  I don't know.  Seems rather an odd disjoint between what is written and what is told when a part may need replacing.  All I know is I'm looking for cracks, am deburring with a renewed religious fervor, and any defective part goes right back. 
 
John Jessen
  ~328 (Tailcone, I think, but now looking for cracks)
 
do not archive

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of McGANN, Ron
Sent: Monday, February 06, 2006 7:07 PM
To: rv10-list(at)matronics.com
Subject: RE: Tail cone bulkhead cracks

I take no offence.  The question I asked was simple enough. The stresses that caused the crack have been removed.  Why can't the crack be repaired?
 
I agree that Vans should be providing us defect free parts in the kit.  I had a cracked bulkhead, informed Vans, and they promptly replaced it.  None of us (except perhaps John) has built, or will ever build the perfect airplane.  Simple economics prevent us from always replacing any part with the slightest chip, scratch or dent with virgin parts.  Repairs in accordance with accepted practice are a part of the build process.
 
We all take pride in our work and do the best we can based on our backgrounds and innate ability.  These forums are an invaluable source of guidance and inspiration, even if some posts are 'over the top' and verge on the personal.
 
Ron
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