Attention! All experts! Respected and others.

[M Towsley]

Re: Attention! All experts! Respected and others.

Hank, and all,

I remember the 'good' hinge brackets in my '43 L-2B. Besides cost, (probably), why did the factory go to magnesium...weight savings, easier to manufacture, cheaper, easy to start a campfire after you crash land from the broken hinge bracket, all of the above? Then again, I don't think they probably thought their airplanes would be flying 75 years later.

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

I'm afraid it was because magnesium was a fairly new "wonder metal" for general aviation around the end of the war and a cast magnesium fitting was a lot cheaper and lighter to manufacture. By the time they had enough service time to realize it was a bad mistake, the company was going through a lot worse problems with restructuring and management changes. It just became a part of the design.
Hank

[Obelix]

Re: Attention! All experts! Respected and others.

If someone has it available I would love to see a pic of the welded bracket vs. the magnesium one. Maybe also a pic of where we should pay attention to, to find that possible crack. My project also have the magnesium ones

[Guest]

Re: Attention! All experts! Respected and others.

If someone has it available I would love to see a pic of the welded bracket vs. the magnesium one. Maybe also a pic of where we should pay attention to, to find that possible crack. My project also have the magnesium ones

Hey guys, Zak has a very good request here.

If we or some of us think that Josh died because of faulty aileron hardware and someone here has evidence of alileron hardware cracking then that evidence should be shared with a sense of urgency. Don't lives depend on this even independent of what happened to Josh? A broken aileron bracket is a serious thing.

Hank please post some pictures.

Guys I think we spent way too much time poking fun at some guy in a thread called "dumb ass mechanic" or something like that and have missed the boat here completely.

Dave

[M Towsley]

Re: Attention! All experts! Respected and others.

Zak,

The aileron hinge bracket I saw fractured where there is a metal tab bolted through at the rear of the bracket. Disimilar metals corrosion started in this area where it finally weakened it and finally fractured.

Though probably hard to find now, I remember from years ago pictures of the two types of brackets being posted on the forum. I will do a little searching later to try and find them.

After a quick search I found these pictures. I am sure I can find more later.

The second picture of a bracket is on an L-2, I believe. The first picture shows where the break can occur with the magnesium bracket. Where you see the tabs attach to the bracket that attaches to the aileron cove sheet metal is the location.

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

Before everyone gets too excited, Josh's plane DID NOT crash because of the broken bracket. The bracket failed because of the crash. The FAA jumped on it early but withdrew it as a potential cause once we explained the failure mode. When a wing strikes the ground there is a high tension "jerk" on the aileron cables to the other wing that can break the bellcrank support hinge. That is what happened to Josh's plane.
I will try and get out to the airport and photograph the types of hinge fitting today. I will try to post them this afternoon or tonight. In the mean time, preflight your plane carefully and raise the ailerons so you can look at and wiggle the hinge fittings. If they are loose, CHECK IT OUT! If they ARE loose, but not cracked DON'T just crank down on the bolts and crush the wood in the spar! Over-tightening the bolts is a real fast way to ruin the spar and break the bolt flanges on the aileron fitting.
If there is ANY chance anyone else could be at risk from anything found about Josh's plane you guys will be the first to know. If we find a suspected contributing condition, we will tell it that way (this COULD have been a problem, everybody go look at it). If we find a CAUSE of his crash, we will call the FAA & NTSB in, but you can bet we will let everyone here know at the same time.
Whenever any of you guys find something that doesn't look right we should share it here. If we all run out and look at 100 questionable problems and only ONE turns out to be a real safety risk, it will be worth it, but DON'T overreact to a suspected problem! I have seen way too many planes damaged by panic about a problem that wasn't a real hazard. Dave is right that we went after the "dumb ass mechanic" the wrong way. He thought he had a problem and he handled it the way he was taught. That is what a GOOD mechanic does, not a "dumb ass". There was a better way to handle it, and being able to learn the better way is the sign of a GREAT mechanic. We can (and should) make good mechanics into GREAT mechanics.
Hank

[Guest]

Re: Attention! All experts! Respected and others.

Hi Hank,

Please include pictures of the cracked magnesium brackets also.

I am working from memory but I think that it was you that may have said that all of your magnesium brackest were cracked. Would love to see details.

Thanks, Dave.

[Ragwing nut]

Re: Attention! All experts! Respected and others.

prewar welded brackets look like the l-2, just a different dimension where they bolt to the spar. the mag brackets crack through the bolt holes where the hinge bracket is attached, and is usually the end bolt that breaks off

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

Dave,
All of the JUNK BOX Magnesium brackets are cracked (in other word I have no spare post war parts). I have some of what I think are good ones in the extra set of wings I have. I haven't opened them up to inspect the fittings. If I can, I want to replace the cast ones with welded ones. I brought a sample set of welded ones from the airport today and found one old broken magnesium one in the junk box. There should be more broken ones in the barn. I remember having a whole box of them but since they were all broken I didn't pay much attention to them.
I got pictures of the cast Magnesium and welded ones and will post them as soon as I get them down loaded.
Hank

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

Here are some photos of the aileron attach fittings. First shot is of the steel crank fitting in a covered wing with the aileron off. Second is a cast crank fitting. The third one is of the broken cast one I found in my junk box with the set of NOS welded steel ones. Note that the cast one is snapped off where it came through the wing aileron cove piece. The steel bolts in the cast one are solidly corroded in place into the magnesium and the flanges where the bolts go through the rear spar are heavily corroded, but amazingly I didn't see any cracks there. I seem to remember the common failure in the box was broken off lugs for the spar bolts.
Hank

[Guest]

Re: Attention! All experts! Respected and others.

Thanks for the pictures and info Mike, Marty, Hank.

[Obelix]

Re: Attention! All experts! Respected and others.

Thanks for the pictures and info Mike, Marty, Hank.

Yes, thanks everyone.

When I bought my project, the wings were already re-covered but I did notice the one aileron bracket could be wiggled somewhat. Nothing vissible from the outside but I will definitly open up and check carefully. Lets hope it is only loose and can be tightened, otherwise I will be in need of a spare or a drawing to make a welded one. Will let the tribe know once I have found the reason.

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

DON'T crush the spar when you tighten the bolts! It is easy to do. There will probably be a thin plywood bearing surface on the spar and there should be large washers to distribute the load on the front face of the spar. Be sure those are good and don't crush them into the spar.
Hank