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Old 02-24-2012, 10:11 PM
Michael Burbidge Michael Burbidge is offline
Join Date: May 2006
Location: Sammamish, WA
Posts: 667
Default Big mistake mounting horizontal stab...


If one hole can ruin an airplane, I might have done it. I am so discouraged!

A few nights ago I mounted my horizontal stabilizer. I thought everything went pretty smoothly and was pleased with my work. Well today I got looking at the holes that were drilled through the HS-908 attach angles into the F-714 deck and I discovered a big problem that I didn't know existed.

I noticed a slight notch on one side of one of the holes. When I got looking at it closer it was the entry point of the initial #40 hole I had drilled through the attach angle and into the deck below. But when I looked closer I saw that the #40 hole went off at a pretty sharp angle. I remember that I made that initial hole with a 6 inch bit and that I saw that the tip bent and went in at an angle. But I had no idea it bent that much. When I enlarged the hole to a #12, I made sure to straighten out the angle, and thought everything was fixed at that point. But as can be seen from the photos below the angle was more dramatic than I was aware of at the time. There's a photo from the top and from below.

I have no idea how I would go about fixing this. With some trouble I can remove the deck and replace the bottom angle, but I have no idea what I would need to do about the longeron, which obviously has a somewhat enlarged hole in it.

Thanks for any suggestions you might have,

Michael Burbidge
Sammamish, WA
RV-14A Wings
RV-9A Flying 340 hours!
Last Donation: December 2020
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Old 02-24-2012, 10:28 PM
airguy's Avatar
airguy airguy is offline
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,319

Your pictures are really good - I would send them to Vans on Monday and ask their opinion, but I'm betting they will tell you to drill it out to the next AN bolt size and build on. Worse mistakes than this have been made and corrected. The edge distance on the off-angle hole is into the direction of the web of the angle where you have excess material, this is the best of a bad situation.

I'm not a mechanical engineer, and I'm not telling not to panic - I'm just telling you not to panic until Vans says panic. At this stage in the build there are about seventeen hundred other items you can work on for a week until you get an answer.
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2021 dues paid
N16GN flying 750 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, IFD440
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.

Last edited by airguy : 02-24-2012 at 10:32 PM.
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Old 02-24-2012, 10:45 PM
alpinelakespilot2000 alpinelakespilot2000 is offline
Join Date: Jan 2005
Posts: 3,683

Don't get too discouraged Michael! We've all had those moments when we've wondered if we've really messed something up. Let us know what Van's says.
Steve M.
Ellensburg WA
RV-9 Flying, 0-320, Catto

Donation reminder: Jan. 2022
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Old 02-24-2012, 11:12 PM
Rupester Rupester is offline
Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,195
Default Also keep in mind ...

... The primary force on the HS is downward. It's not like there will be constant or significant loads pulling upward on that rr deck. I suspect drilling out to the next larger bolt size will work, but Vans can/will confirm or deny that.
Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '18)
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Old 02-25-2012, 12:02 AM
vmirv8bldr's Avatar
vmirv8bldr vmirv8bldr is offline
Join Date: Jun 2005
Location: Eastvale, CA
Posts: 378
Default I did the same thing. Twice.

Don't feel bad about it, I did the same thing only I did it twice. I noticed the mistake before riveting though and opted to replace all the affected parts. It was the most expensive mistake on the whole plane at about $200 +/-. I was later able to use the scrap parts elsewhere in the plane as stiffeners, etc.

I've learned two things building the plane:
1. I'm going to mess things up occasionally.
2. Anything I mess up, I can usually fix.
Bart Filipiak
Eastvale, CA
RV-8 N74VB

Barrett IO-390
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Old 02-25-2012, 08:07 AM
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jcaplins jcaplins is offline
Join Date: Feb 2006
Location: Davis, CA, USA
Posts: 544
Default fill-n-drill?

Would it be considered acceptable to fill the holes with JB-Weld and re-drill?
Jeff Caplins
(started: Feb 2002 --> Completed: May 2016)
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Old 02-25-2012, 08:26 AM
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flion flion is offline
Join Date: Dec 2007
Location: Flagstaff, AZ
Posts: 2,672

I was thinking along the same lines, though I'd still check with Van's. Since it's so very near the end of the longeron, you could fill the holes, back up the longeron with a 1/16" thick piece of aluminum stock, and redrill. Then use a slightly longer bolt through the redrlled hole and backing piece. I'd probably make the backing piece long enough that both bolt holes pierced it.
Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
EAA Technical Counselor #5357
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Old 02-25-2012, 08:42 AM
Rupester Rupester is offline
Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,195
Default On the wall of my hangar ....

"Any mistake can be fixed. Sometimes with time, sometimes with money - - but usually both."
Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '18)
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Old 02-25-2012, 09:39 AM
Tom Martin Tom Martin is offline
Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,564

As suggested, call Van's. If it was my plane I would replace the underlying angle at the very least. I have some concerns that the additional hole in the main longeron weakens that primary structure. JB weld is a great product, and has it's uses, but all it is going to do here is make you feel better. It is not going to remove the stress point.
Van will likely tell you to replace the underlying angle and move on but do get their opinion and follow their advice.
Tom Martin RV1 pilot 4.6hours!
CPL & IFR rated
EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
RV14 Tail dragger

Fairlea Field
St.Thomas, Ontario Canada, CYQS
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Old 02-25-2012, 09:56 AM
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rocketbob rocketbob is offline
Join Date: Jun 2006
Location: 8I3
Posts: 3,647

I've been around aircraft stuctures a long time and have seen quite a few repairs in the certified world and my opinion here is you really don't have much to worry about. There would have to be a tremendous negative-g force required to fail this joint as-is. For this joint to fail the longeron would have to bend out of the way, and angle attached to the bulkhead would have to be ripped from it. Going the other way (compression), all the bolt is doing is holding the HS in position with virtually no load. You could put a triangular reinforcement, a shim forward of the angle underneath the longeron, and bolt this in to add some more strength to this joint.

Please don't PM me! Email only!

Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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