Strut Attach/Wing Tie Down Fittings

While hanging out at Oshkosh my Dad and I were asked to look at a Tri-Pacer that had some questionable front strut attach fittings. It was interesting because the airplane belongs to the president of the Short Wing Piper Club.



He latter came by and asked us to look at it as well.




I knew he had left the airplane for several weeks after getting stranded by weather and figured it was tied down in a wind storm when looking at the damaged strut attach fittings. He asked me if I thought it was safe to fly and I let him know that I did not. Anyway, we got Univair to FedEx in some new strut attach fittings and new hardware and behindpropellers dropped off a nice collection of tools including a cordless Bosch sheet metal shear along with a 1/2" swivel socket and long extensions. My Dad and I were able to swap out the fittings at the owners parking spot in the Vintage area. Only real challenge was on the left side at the bend. Was hard to bend the fitting enough to get a socket on it.







After the fact I believe the fittings have been this way for a long time. Curious to hear if it flew any different.

Steve Pierce said:

View attachment 38338
After the fact I believe the fittings have been this way for a long time.

Click to expand...

Looking at the rust in the bent area it does look as though it has been bent for a while.

Wow! That's quite a bend. Did the strut attachment for the other wing look like that? What did the bolts look like?

Did he say what he used to tie it down? I'm thinking about the several discussion on this forum about rope vs chains, etc.

Jim

Those look pretty similar to the ones from the Cub I flew in Kodiak. Plane had been tied down with chains over winter several years before I got there. The accident in Anchorage was what prompted us to look more closely at the fittings. The right was pretty bad, the left not so much. Scary stuff.

Good for you for getting him going and safely again. And thanks for the reminder. Seems like this needs to be brought up every once in a while as a reminder.

Thankfully, this reminder has a happy ending.

Memo to all: DON’T TIE DOWN WITH CHAINS!!

MTV

Don't tie down to strut fittings. Atlee has a fix for that.

Bolts appeared to be ok but replaced them anyway. Both sides were the same. Owner had no idea and for all he knows it could have been that way for the 20 plus years he has owned it.

For guys who don’t have spar tiedowns installed. I can’t imagine changing out bent front attach fixtures without including these. http://www.fadodge.com/lift-strut-reinforcement-bracket/

Steve, I think I read that you were able to replace the damaged parts on site at Oshkosh...true or false? If so, I assume you were able to do so without opening up the wing? I would be interested in knowing how you did that, what tools you used, etc.

Stewart, I looked at the pdf you referred to and am not sure how extensive/difficult it is to make that change.

Randy

WindOnHisNose said:

Steve, I think I read that you were able to replace the damaged parts on site at Oshkosh...true or false? If so, I assume you were able to do so without opening up the wing? I would be interested in knowing how you did that, what tools you used, etc.

Stewart, I looked at the pdf you referred to and am not sure how extensive/difficult it is to make that change.

Randy

Click to expand...

Takes less than an hour

Cut a small hole in leading edge for inspection plate on bottom.
Drill hole up through top above installation point and cut a small hole there
Slide tiedown in place
Install 2 bolts
Put covers on or patch holes


Sent from my iPhone using SuperCub.Org mobile app

I think Mike’s describing the hurricane tie. The reinforcement I linked is a doubler that fits nicely into the spar attach fitting when you bolt it on. It’s made to prevent the bending shown in Steve’s photos. The hurricane tie is a better solution but probably more than guys who usually park in hangars need.

WindOnHisNose said:

Steve, I think I read that you were able to replace the damaged parts on site at Oshkosh...true or false? If so, I assume you were able to do so without opening up the wing? I would be interested in knowing how you did that, what tools you used, etc.

Stewart, I looked at the pdf you referred to and am not sure how extensive/difficult it is to make that change.

Randy

Click to expand...

Cut another inspection hole in the leading edge with the Bosch cordless sheet metal shear. Had to try and bend the fitting where it had kinked to get a socket on it. The 1/2" swivel socket and long extension were key along with some line up bars.

I think the hurricane tie downs are key to not having this issue. The Atlee Dodge reinforcement that Stewart linked would not work on this Tri-Pacer and would be hard to fabricate because the fittings are shorter than the Super Cub with the bolts closer together.

Given the evidence that it's a weak spot? It would be worth making something to address it. I can't think of many parts that would be so simple to fabricate. Kracke would probably do them on request.