The International Cessna^® 170 Association

Had a freak on the ground incident at some point last week and wanted to get some advice from the fine folks on this forum. I likely won't express my thanks as clearly as some can but know that I do appreciate your help.

So my plane sets on my Uncles property under an open type 40 x 50 hanger. On back left corner of the hanger a small ford tractor is parked as well. It sets about 10 feet to the left of the tail wheel tie down point. My uncle was out doing work around the place as he does on most every day and he notice that the left side of the plane was setting down a lot lower than usual and suspected that I had a flat. At some point he decided to check it out before calling me to let me know before I showed up to fly and be disappointed.

What he found was surprising to say the least. The small ford tractor was pulled up against the left wing tie down strap to the point that both mains has jumped their chocks and the tail wheel had jumped a 2x4 used to keep it in line when towing out. It had the 26" good year tire on the left side squatted to the point that it looked almost flat. I did not get to see any of this as he thought I was out of town and did not call me until he got the tractor backed off the tie down strap and the plane back in the proper position.

He questioned his grandson that had parked the tractor last, trying to figure out who ran it into the strap. His grandson denied and thus the investigation followed. In his effort to get the tractor off the strap the battery was dead. So he had to get something to jump it and get it backed up to the proper parking location. As he left the tractor he made it about 20 feet behind it and the tractors starter kicked in and to his amazement it started right back down the same path which was the tie down strap. He was able to get to the tractor before hitting the strap for a second time. In all of this, his tone of voice while tell me this made me chuckle. He was in complete awe that his tractor just tried to start on it's own right in front of his eyes. So he parked the tractor again and pull battery cable off. During all of his work to resolve the issue his tractor was actually starting itself before it was over. Obviously there is a short somewhere causing it to bypass the proper safety switches but now to my real question.

The only visible damage is to the plane is in the tail wheel area. The tie down rope bent one of the ears where the change hooks to that is hooked to the spring. I am not a 170 expert so I have concerns about any other stress type damage that might have been done that is not visible to the naked eye or specifically my naked eye.

My annual is due so the timing is good I guess but my uncle's response of those wing struts are tough and it fine is not good enough for me to not think about it the next time I want to leave the ground.

I did not get the pictures placed in line with the store but the last one is looking from the tractors point of view and the tie down strap it pushed on.

Thanks for any input you can provide.

I say you were very lucky! It's very fortunate the tractor did not start or otherwise the plane would have probably been destroyed. Pointing the tractor away from the plane when it's parked might be a good idea too. In case it starts again it will drive itself away from the plane. He might want to leave it parked in neutral and chock the wheels to keep it from running over something else.

Just going by the pictures, if there is no distorted, bent, or warped metal anywhere, the plane is probably alright. But don't assume anything. If possible, I would get the mechanic to come do the inspection where the plane is hangared and not fly it to the shop. Or if he says it's ok to ferry after he looks at it, go ahead.

The tailwheel steering arm is a heat treated part which is more brittle than soft steel. It may crack or even break if you try to straighten it. In any case, I would take the tailwheel off and have it repaired by a mechanic familiar with Scott 3200 tailwheels before I flew it again.

The movie "Christine" comes to mind.

I was thinking Maxinum Overdrive.

Thanks for the reply folks. I can't see any distortion but it just makes me nervous to see that much pressure put on that on wing for that long of a period. Exact period is unknown, parked the evening before and found midday the next day. Long enough for the battery to run dead.

Justin

Presuming that all the tractor did was pull down on the tie down strap it most likely did no damage to the wing. Wrinkling in wing skins would be evident. However I would have the landing gear fittings inspected in the area where the landing gear attaches inboard & outboard on that side as from what you describe the tie down was literally lifting the wing on the opposite side of the airplane using the landing gear for a fulcrum. It is also possible that damage may have been done to the axle on the side that had the tire flattened, it could be cracked or bent. And you do not want to find out when you fly it.
It is likely that the landing gear attach bolt on the inboard side of the gear was in a compression load which would not have hurt it. but it may have experienced a shear load as well which could have damaged it. If you are going to remove it to inspect it you may as well replace it.
The wing between the outboard strut attach and wing attach at the fuselage was in tension so it probably did no damage to it. but the Lift strut would have been in compression the fasteners and strut should be examined for any deformity. My guess and it is just a guess that no real damage was done to either the strut or wing, but i think they should be looked at by someone who knows what they are looking for.

Well I called it down but it was more like the tractor pushed outward on the strap until the mains jumped the chocks and the tail wheel was pulled over the 2x4 runner in the same direction the tractor was push on. I guess when the tractor go so far upon the strap it started pulling in a down/forward motion. So there was a tugging match between the tractor pushing on the left wing tie down strap and the tail wheel being held somewhat in place by the tie down strap for it. The tail wheel tie down only holds for forward movement not side to side. Then you had the tie down strap on the right wing hold that wing down in place short of whatever give it had when the other wing was pulled forward/down.

Thank you for your input Metal Master. I don't fully understand everything you said, no sense in pretending I do. Hopefully my IA will have some clue on how to make sure this bird is safe for me and family.

What Metalmaster was saying was that the wing struts are designed to be strongest in tension.... such as if you were pulling on both ends of it to stretch it. They were not intended to be particularly strong in compression..... such as if you were trying to shorten them by pushing inward on both ends.
The same is true of your wings and the attach-points at the struts and the wing-root.... They were intended to lift the weight of the airplane, suspended beneath.... Not to "fulcrum" it over the wheel/gearlegs by pulling down outboard of the strut-attach.

Look for signs of stress on the left wing such as wrinkles in the lower wingskins and at the lower strut-to-fuselage attach point. (The right wing was subjected to far less stress and whatever it experienced was more normal for it's design.)

Thanks for the info George. I think I unstood what "Metal Master" was saying but wanted to try to make sure I had been clear about what took place.

Is this something I should notify my insurance about or wait to see if the inspection reveals anything suspect.

Justin

Wait to see if your inspection reveals any damage. Best not to get the insurance company involved unless you do find damage.