Well it's not a very good day for N91393 here's what my son found doing annual inspection.

So if anybody has a bracket p/n 0713495-8
and as if thats not enough, on further inspection the angle that the outboard bracket rivets to is also cracked p/n 0713495-5

This is a 1969 180H

Help

Marty

Check pponk.com they make those brackets.

PPONK makes a better and stronger bracket than Cessna.

Good used Cessna brackets are available through Skywagon City in Canada, Peter Muehlegg.

I'll soon be offering a better and stronger bracket than both the above, but it is not yet approved.

P Ponk was my first call. However they don't sell the inboard bracket, the one the beef-up kit attaches to, $1,360 on Yingling.

They don't sell the angle at the lower side of the outboard bracket either. P Ponk does sell the outboard bracket however.

Marty

I thought I would post a few more details as I have more time now since I'm home. Well we had started the annual a couple days ago, and after jacking the plane up we found the right gear to move ever so slightly. Upon further inspection the outboard gear leg bracket was found to be moving. At that point I removed the gear leg and that is when we could see the inner granular corrosion that you can see in the picture on the inboard gear leg bracket, this is the bracket that the P Ponk beef-up bracket bolts to. Then Ben my son and my A&P IA inspected further and found five seared rivets in the lower angle and the angle itself was cracked on the outboard gear leg bracket.

I kept trying to get him to wear some foggles but for some reason claimed he couldn't. But seriously the only other way to find this is to have the gear buckle under someday. So I'm very glad he found it when he did. The hardest part is this is my first annual after buying the plane last April. I sure however that the previous owner could NOT have known about this. The only way this could be found is pulling the gear leg.

So I will be replacing the outboard gear leg bracket with the new P Ponk bracket, but still need to find the other parts that P Ponk does not sell.

If anybody has any experience with this tpe of project let me know what I might expect, and what to look out for.

Thanks,

Marty

Marty, how did you lift the plane?

Can't your A&P/IA fabricate a replacement part himself?

Gump

Glidergeek, I built a couple of 4"x 4" partical board blocks 1 1/2" thick and then added some dense rubber to the top (the service manual called for 4"x 4" and 4 layers of 1/4" masonite). Then using aircraft jacks place them at the top of the wing strut centered on the wing spar and jack carefully. You also need to hold the tail down as the plane becomes very nose heavy.

After we did all of this and found the problems, I built a wooden support to place under the plane. Drilling out the top of the gear boxes would involve removing pieces that are structural, so the plane could not be supported by the wings alone at least not and be able to sleep at night.

I'll post picture of the on going project a little later.

Marty

Can't your A&P/IA fabricate a replacement part himself?

Gump

You know I talked to Ben about that and this particular part is a cast aluminum channel, at least 1/4" thick. I don't know what we could fabricate it from that would be the correct dimensions.

Marty

Any good machine shop should be able to do it, and as far as I know it's allowed by the regs.

Gump

Any good machine shop should be able to do it, and as far as I know it's allowed by the regs.

Gump

I'll talk to him tomorrow about that. I hadn't considered talking to a machine shop. Ben should have a pretty good idea about the regs. I hope your right that would have to be considerable cheaper.

Thanks Gump,

Marty

That's a bummer. Been there. My only advice is when you find the parts get the stuff for the other side too. That intergranular is sneaky stuff. When you get it buttoned back up make sure you have those rubber seals that go around the gear leg in place. Exhaust gas is what takes out most of those gearboxes, believe it or not.

Ok here are the pictures of what I did today. I'm pretty sure I have never drilled out this many rivets in one day before and I'm not done yet.

I didn't start taking pics until a couple hours into the day. Flap handle removed.


Trim wheel removed. You can see a repair done back in '82 on the LH gear box


This is the '82 repair, you can see along the inboard edge where there was enough movement of the repair to shear off six #6 cherry max rivets.


I have one more pic to upload , but Tapatalk will only let me do 3 at a time.

Marty

Here's the last pic of the day.

All opened up.


Should get it all out tomorrow, the good the bad and the ugly.

Marty

I just got off the phone with my IA, and his opinion is that under Part 43, major repairs, you're OK to fabricate a direct replacement part out of equal, or better, material as long as there are no alterations to the design. Such as a gear box part, firewall, etc, etc...

YMMV with your son's interpretation of the regs. But certainly worth looking in to.

Gump

Gump, I'll be looking into this first thing in the morning. Also not to look stupid but, YMMV?

Marty

Your Mileage May Vary

Even us old guys got this texting shit down pat!

Gump

I'd give a call to Beggles Aircraft in Greeley, CO and talk to either Scott or Dave . They rebuild more 180/185's than any other shop by far and have first hand knowledge on where and how much for the parts. They have 8 or more skywagons at any one time getting repaired or upgraded. They also part out skywagons.
Ron

180jocky wrote:
You know I talked to Ben about that and this particular part is a cast aluminum channel, at least 1/4" thick. I don't know what we could fabricate it from that would be the correct dimensions.

Marty

That part is an extrusion, not a casting. A casting would not be strong enough with that thin of a "wall thickness". Look at the main gear outboard bracket on a Cessna tricycle aircraft to see how much thicker a casting has to be than an extrusion.

The nominal distance between your front and rear gear box bulkheads (and doublers) is 6.875 inches. The inboard gear bracket is that distance in fore-aft length, outside to outside. The material is 2024-T4 or T-6. It is not standard T-3.

The shape of this inboard bracket, viewed from the side, is NOT a rectangle. It is a parallelogram 3 or 4 degrees "off-kilter". The hole pattern is identical front versus rear, but the hole patterns are OFFSET VERTICALLY by about .093"... the rear holes are higher than the front holes.

The main channel section can be machined out of a block of aluminum on a mill. Make sure there is a decent radius in the corner. If I am remembering, the "wall thickness" is nominal .1875 inches. You will have a fairly expensive pile of shavings on the ground. 2024 alloy cannot be 100% reliably welded like 6061 can, and the FAA engineers will be very uneasy (and justifiably so) about welded 2024 unless you are Boeing. So you cannot weld it out of 3/16" plate.

I believe PPONK makes the inboard mounting angle. If they do not, your machine shop can make this angle out of 2024 bar stock. The fancy radius can be done by milling, or to be honest you can just leave the radius out and have a huge massive rectangular bar. The weight difference will be a few ounces. There is a lot of load on the fasteners holding this angle into the main channel, and it is a poor design because the angle does not connect directly to the mounting flanges. So all of your loads go through the ten bolts, and these holes should be a good tight reamed fit, I suggest NAS bolts instead of AN bolts.

Your biggest problem will be drilling the holes in the replacement part to match the holes in the aircraft. Sorry, that's going to be a bitch, and this is the one place where you need perfect holes with no slop.

But the answer to the core question, regarding making an owner produced replacement part, is that this channel is not rocket science and any machine shop can hog this out of a block of metal.

EZ, you are very correct that it is extruded not cast. I got it out yesterday and found I was off base with my earlier assement.

I did talk to P Ponk again, and while they still have not started making this part he told me everything in the gearbox he thought was 2024 T3. After reading your post I'm questioning what it really is and how to go about finding out.

Lots of good information, thanks EZ,

Marty