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  #1  
Old 10-24-2017, 03:58 PM
flion's Avatar
flion flion is offline
 
Join Date: Dec 2007
Location: Flagstaff, AZ
Posts: 2,708
Unhappy Well %#@&!!!

It's taken me a few days to gain emotional distance enough to deal with a huge setback in my project. I had bought an aircraft lift, which seemed like a great assist, both letting me move both aircraft into the hangar and also positioning the aircraft to work at a convenient height. I had contacted the lift manufacturer for maintenance info (it was purchased from the estate of a pilot here in Flagstaff) and they recommended retro-fitting the jack-screw mechanism with a chain hoist. Well, I should have listened because the lift failed on the 16th while I was lowering it to work on the project. Fortunately, that meant that the -6A was safely outside the hangar and I was not under it because it is operated from the side.

I would estimate the weight of the lift yoke (which the fuselage on gear was strapped to) and the fuselage to be close to 3000 lbs. It did not free-fall due to the geometry of the lift but I came down very fast from between 3 and 4 feet, to a sudden stop on the hangar floor. Due to the added weight and the fact that the wings weren't on (no aerodynamic drag like you'd find in a stall landing at that height), I'm sure it's like stalling in from a greater height.

So, the good news first. You'd definitely survive such an incident. I'm not sure what the wing attachments would look like but the fuselage structure was largely intact. Now the bad news. On closer inspection, the side skins were wrinkled low behind the main spar carry through and the bottom skins were wrinkled behind the mains all the way across. The pictures don't show it too well. The was also slight wrinkling at the panel attachments to the side skin. More good news: I won't know for sure until I disassemble everything but it looks like all the rest of the structure is Ok. The floor and seat pans are fine and I'm hoping the ribs underneath are the same (though I will, of course, check. All lateral forms are fine. I expected to find some stress around the baggage door, which was open, but found none. The entire tail cone, including empennage attachments, show no signs of stress. And likewise on the firewall, which had the mount and engine. The gear also checks out.

The big disappointment is, even if the skins are the only things to replace, it means I will just about have to disassemble the entire project. The fiberglass top (fortunately not bonded) will have to come off, along with the engine and panel, seat and floor pans, tail cone, and likely much of the wiring runs, plus the possibility of finding some hidden damage. If the firewall had shown wrinkles, I would also be sending the engine mount back to be checked - no cracks but I'd worry about deformation.

So I'm not really posting all this to vent (Poor me!) but to give some praise for how tough this structure is. I'm not sure I'll trust a lift again. It worked great while I had it but the consequences of its failure is just too much to risk again. By the way, this thread is not about the lift, either. If you want to discuss the pros and cons of lifts, start a new thread. This really is about how the structure stood up to an unusual situation. Pictures follow:


The wrinkle in the side skin is hard to spot but is about at the third hole in the bottom skin aft of the spar and 'peters out' before the line of rivets about midway up the spar.


Again a little hard to see due to lighting but the wave where the two bottom skins overlap extends all the way across the fuselage.
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Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
http://www.mykitlog.com/flion/
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  #2  
Old 10-24-2017, 06:27 PM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 2,729
Default Oh Man....

Bummer....
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  #3  
Old 10-24-2017, 06:31 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
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Would insurance cover this kind of damage?
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  #4  
Old 10-24-2017, 06:54 PM
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Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 3,520
Default

gear could not flex. bummer, but consequences not as bad as failed jackscrew in Air Alaska flt 261. recently, I have been reviewing failed jackscrews, more common than you would think.
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Last edited by Steve Melton : 10-25-2017 at 05:19 AM.
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  #5  
Old 10-24-2017, 07:08 PM
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ColoCardinal ColoCardinal is offline
 
Join Date: May 2010
Location: Morrison, CO
Posts: 372
Default

So sorry to see that Patrick.
I'd like to say; look on the bright side, but other than not worrying about it's first ding, there really isn't one.
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  #6  
Old 10-24-2017, 07:32 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 4,676
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That stinks. Hopefully, you can get your mind around fixing it and moving forward.

If you were closer, I'd grab a drill and a 6 pack and help you drill everything apart...
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  #7  
Old 10-25-2017, 01:06 AM
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az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
Question

Definitely stinks...

Was the deformation of the skins caused by a compression of the spacer material between the two sections of the spar pass through?

Perhaps a precise measurement of that spacing top and bottom on both sides would be in order?
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  #8  
Old 10-25-2017, 12:30 PM
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ppilotmike ppilotmike is offline
 
Join Date: Jan 2010
Location: Denver, CO
Posts: 2,014
Default Jeez Patrick..

..I'm really sad to hear that. I really appreciate you starting this thread though, as it does show the robustness of the 10 design. I'm a bit confused by the comment about the gear not flexing. Wouldn't the gear flex during this event, taking some of the shock? Also, I bet that if the cabin top had been fixed to the fuselage, it would have taken some of the compression loads on the belly away, in the form of tension through the top's connections. Really, really bummed for you, man. I hope you'll get her fixed. I'm right behind you, although I haven't bought my panel, engine or prop yet.
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  #9  
Old 10-25-2017, 12:38 PM
Berchmans Berchmans is offline
 
Join Date: Nov 2009
Location: Anchorage, Alaska
Posts: 465
Default Aircraft lift

The jack screw system on my lift wore out as well. I noticed metal shavings on the screw when operating the lift. Fortunately I did not suffer a complete failure of the ACME nut causing the lift to fail. I did retro fit the lift with electric chain hoist but did not use the kit provided by the manufacturer. His kit is fine but after pricing and shipping costs to Alaska I found that fabricated my own design for the modification of the mast was much more cost effective. The electric chain hoist required is a 2 ton model. The way I modified my lift I did loose some of the lift range but I am limited by roof height anyway. I spent a total of about $3,400 on the retro fit. It does require some heavy lifting. My modification did not require any cutting on the mast but you do have to drill some holes.

You should inspect the jack screw closely after any operation and see if there any metal shavings in the threads after operation.
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  #10  
Old 10-25-2017, 01:09 PM
woxofswa woxofswa is offline
 
Join Date: Sep 2007
Location: Mesa Arizona
Posts: 662
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I am truly heartsick. You probably don?t want to hear this, but I think I would probably start over with a fresh QB fuselage simply because I think you would always be wondering where all that energy went and if you found every stress and tweak.
Let the community help get you back whole. If someone starts up a hull replacement fund, I?m in. I think lots of guys would contribute. Then you can take the old carcus out and blow it up or shoot it full of holes.
If you decide to repair and want help drilling out rivets, I?m also in.

Dayum, I feel for you. I?d still be throwing up. Nevertheless, don?t give up. It can be resolved.
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