PDA

View Full Version : Fuselage inspection after ground loop



clipquito
09-22-2010, 02:39 PM
Sad to report that I ground looped my beautifully and very recently rebuilt Clipper. Feel like I am back to square one with so many (novice!) questions about how to proceed with repairs. I'll start with fuselage which appears to be unharmed, but...

The wing did not drag during the ground loop. We turned 180 degrees, left main collapsed and the wing dropped to the ground. The wing bolts came out very easily. Connections appear NOT to be twisted. Same for the main gear leg -- bolts came out easily, no visible damage. How do I go about checking for cracks in the wing and gear connections -- assuming I should do that?

Took the front underside panels off -- between the mains. 1/4" channel they attach to is bent -- wavy. Wondering if I can just straighten that as it appears to be non-structural. Main tubes on the front underside appear to be unharmed. How would I go about checking whether or not they are straight as they appear to be?

Another 1/4" channel on the left front of the fuselage is also bent -- curved. Took the floor board under the seat off to look at it. Can't figure out how it got bent since the gear did not collapse onto it at all. I'm pretty sure I can just tap it down, but should I and how would I check the main fuselage tube adjacent to it to see if it is straight?

I am told by some A&Ps that the welds (those closest to the gear??? to the front of the fuselage???) need to be inspected for cracks. How do you go about doing this?

How would I know if the fuselage in general is straight -- that is, not torqued or twisted -- although it appears to be perfectly straight.

Finally, does an IA have to sign off on these items or can an A&P do them?

Thanks so much. I would appreciate any pointers in the right direction. I thought the rebuild was overwhelming, but this is something else altogether!

Curly
09-22-2010, 05:42 PM
Clipquito - I feel your pain! It's almost like hurting a person you love and care for.
However - one of the great things about our shortwings - they are like a old dog - they will love you whatever you do.

Good luck with the repairs! :smile:

clipquito
09-22-2010, 05:53 PM
Thanks for the empathy. It helps. Hoping to get some good info for how to proceed with inspections and repairs.

captbill1956
09-22-2010, 09:36 PM
I have not done a ground loop inspection on a shortwing, but I did learn that the structural tubing on a TriPacer can be bent substantially and not be readily visible from the outside. I had some tubes bent in the firewall area where the nose gear mount and engine mount bolt on, that could not be seen from the outside and weren't found until I stripped it to the bare frame. My point with this story, is that you MAY be looking at stripping the fabric off the fuselage partially, if not fully to find any possible damage. Small structure as you describe that is now wavy (previously straight) MAY indicate that the big structure to which it is attached is bent or broken. Same with your wing. If it dropped all the way to the ground, I would be wary of damage within that wing, or to its attach points and struts, that might not be readily apparent. Paying one the the guys on this list that make their living working on this stuff to come assess the damage, may be a worthwhile investment. Good luck with the project. I know it must be a gut wrenching experience. Keep us posted on your progress.
Bill Meredith
N7749D
Kingsland, TX

Steve Pierce
09-22-2010, 10:16 PM
The bolts coming out of the wing with little effort is a good sign. The landing gear fittings bend easily. Inspect around the welds with a magnifying glass. Install straight gear and see if it bolts up without having to beat it together. Look the fabric over and see if there are any wrinkles. I bought my Pacer from the insurance company as salvage. One gear was broken off, one gear was extremely bent, the wing drug the ground and the prop was damaged beyond repair. I rebuilt both landing gear in my jigs, did a prop strike inspection on the engine, inspected the internal structure of the wing through the access holes and looked for loose fabric. Varnished the exposed wing tip and patched the fabric. The 3/8" channel in the belly was bent so I used a flat piece of steel that would fit inside the channel and slowly and carefully tapped it back into place. I found no cracks anywhere and I flew my kids to New Holstein/Oshkosh in it after the repairs. These are pretty robust airplanes.

clipquito
09-23-2010, 09:08 AM
Thanks Bill and Steve for the input. Dumb question Steve, but do I need to strip(?) grind (?) the paint off the welds and gear fittings to inspect them? Will be looking at the wing today, but I believe it is a total rebuild -- both spars bent. Aileron looks beyond repair -- looking for a good used one. Hoping you will build me a new gear leg in the near future. Do you think I need to worry about the RT leg being torqued? There is a slight wrinkle on the trailing edge of the RT leg fabric. I added the balsa wood pointy things on the trailing edges -- don't know what to call them. That is where the wrinkle is. I'm inclined to think that is a gluing problem more than a torque. Someone told me to put two chalk marks on the ground and see if it rolls straight, but I will need the new left main to do that I would think. Elevator is bent (curved) slightly on the trailing edge -- looks to be an easy fix (ha! can't believe I said THAT!). Stabilizer brace wire twisted a bit -- will inspect the welds, but it looks like it will go back pretty easily or be replaced. I'm mostly worried about the fuselage. Really don't want to take fabric off it -- or boot cowl/windshield either. I see NO fabric wrinkles anywhere on the fuselage. Just have the curved channel issue on the left side that may indicate a problem with the main structural tube next to it, as Bill suggested. That's pretty much the extent of the damage. I would appreciate any other input you might have.

nicka
09-23-2010, 10:24 AM
When your looking over your fueselage there are some other small indicators you can look for, such as fit of the door, or the flight controls rubbing in places they did not before, that would indicate possibly bent structure,Also just stand back and look at how your cowls fit, Do they seem to be rubbing or interfering in places where they did not, all of these can be indicators of hidden damage.Also as far as your welds, if you as Steve said, look at them w/ a magnifying glass, you can also pick up a dye penetrant kit, if you think anything is cracked, Most aviation parts stores have them, they come in spray can like paint and you just have to follow the instructions on the can, its really easy to do, But just go over the fueselage and the way the parts fit is a good indicator of bent structure,Seems really bad now, but you will get it fixed and get going again.

clipquito
09-23-2010, 11:14 AM
Thanks so much. That is very helpful. I appreciate it. Thanks for the words of encouragement too. At the moment it does seem like it will never end. BA

nicka
09-23-2010, 12:04 PM
The famous airplane rebuild mantra I keep telling myself w/ my little fiasco, "It is only time and money" otherwise no big deal.

clipquito
09-23-2010, 08:22 PM
Roger. Wilco! What fiasco are you dealing with?

nicka
09-24-2010, 10:50 AM
I have a PA20 that is a complete ground up rebuild and I am rebuilding one of the wings right now, between repairs and the modifications that I am into it hard to tell someone that does not work on airplanes how much labor goes into these projects.

clipquito
09-24-2010, 11:06 AM
No kidding.