Bald Eagle Aviation

51fixer · **Posted:** Sat Nov 03, 2012 5:06 pm

Some work done on 22-
Years ago I purchased a couple T-6 Surfaces out of Omaha NE. One of the parts was a Vertical. It looked pretty good, at least I was told that, but it was full of mouse or rat housing so ended up sitting on the shelf. I remembered it was AT-6A so I drug it down as I wanted a couple items off of it.

S/N 41-16345
Google shows it was Ground Looped on Landing 6/11/45 at Truax Field, WI while part of 3508BU.

The Data Plate on the AT-6A Vertical shows-

P/N 55-23001-16K
S/N 558-T-896
MFG Date- 12-21-41

Compare with SNJ #22s Vertical-

From the SNJ-3 BU 01796
Vertical P/N 55-23001-1
S/N 558-T-750
MFG Date- 12-11-41

So it looks like it took 10 days to make an 146 Vertical Stabs in the Middle to Late Dec of 1941. The acceptance date for SNJ #22 was Dec 29th with S/N 750 vertical. Wonder when 41-16345 was accepted?

The parts I wanted are the Rudder Attach Brackets from the AT-6A Vertical-

I had my youngest son remove them, (glad these have nut plates) and here are some details-

It looks like the Spar was painted Silver as an assembly. The flange side of the brackets are green-

The bracket green is a bit lighter than this other original green we have identified (the lighter green is orig and the darker green is from CC O/H in 44)-

The Silver on the AT-6A Spar-

The reason for using the AT-6A Brackets is I found this on one of 22s Elevator attach brackets-

Apparently at Corpus Christy they bored all the brackets OS and bushed them with an NAS75 Type Bushing pressed in place. The Inner part of the bushing doesn't match the machined edge of the bracket and steel pressed into forged alum presents a corrosion issue. This can lead to the crack as found and shown in the photo.

Speaking of cracks, there is an AD issued on the T-6 Horizontal Spar End Fittings. All the fittings for SNJ #22 were in a box when we collected this project and not bolted in place.

I broke out my Horizontal Fixture and put one in place so I can try to match up which fitting goes where. The best part is this came with 5 used fittings in the box. A single A/C has 4, 2 on each horizontal. So where did the 5th one come from?
The Horizontals are symmetrical and fit either side. The same with each Elevator Surface.
Going back to the AD-

These are the cracks that can form on the fittings and the reason for the AD.

AvroAvian · **Posted:** Sun Nov 04, 2012 7:33 am

Would you fit the later model two piece fittings in their place Rich? I believe there is no further inspection requirement for them.

51fixer · **Posted:** Sun Nov 04, 2012 9:20 am

All the "Later Fittings" are is the orig type cut in 2 parallel with the spar.
The AD will be complied with. There is 2 ways to comply.
By installing the split type fittings.
By measuring any gap that exists when the orig type fitting is in place and adding a shim if needed.
It is the gap that causes the problem and the cracks.
This A/C had been under restoration when the AD was issued but the way the AD is written it only applies to T-6D, F and G. The AT-6A or SNJ-3 isn't named in the AD.

FAA AD here-
http://rgl.faa.gov/Regulatory_and_Guida ... #_Section8

AvroAvian · **Posted:** Mon Nov 05, 2012 7:51 am

This http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAD.nsf/0/D1595A2361D5F4D686256A450068CE7C?OpenDocument is applicable to the SNJ-3, but it only mentions shimming any gap between the fitting and the spar. I am surprised that the use of the later two piece fittings are not mentioned as an AMOC. My interest in this is with the Wirraway, which is roughly equivalent to the BC-1 and suffers from the same problem.

bdk · **Joined:** Sun May 02, 2004 1:16 am **Posts:** 11324

You can get these new from Lance in NAA packaging in either the single piece or two piece configuration. I got the two piece for one side and cut the other side myself. You can also oversize the holes to the next larger diameter bolt size per the structural repair manual if you need to clean up the holes.

51fixer · **Posted:** Mon Nov 05, 2012 9:46 am

AvroAvian wrote:

This http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAD.nsf/0/D1595A2361D5F4D686256A450068CE7C?OpenDocument is applicable to the SNJ-3, but it only mentions shimming any gap between the fitting and the spar. I am surprised that the use of the later two piece fittings are not mentioned as an AMOC. My interest in this is with the Wirraway, which is roughly equivalent to the BC-1 and suffers from the same problem.

I don't think the AMOC was prevalent back in 1950 when this AD was introduced. Many older ADs haven't been updated.

Matt Gunsch · **Posted:** Tue Nov 06, 2012 1:37 pm

Here are some samples from my show and tell collection
cracked and exfoliation corroded

cracked

NOS never installed

snj-5 · **Posted:** Tue Nov 06, 2012 7:14 pm

Here is the NAA drawing for those fittings. I had several shipsets on hand when I rebuilt my horizontal stabs for the SNJ-5, but most of them were junk (could only come up with one pair that passed muster which I cut in half myself). FYI, the NOS fittings I received from Lance didn't have the end mill / spot faced areas (for the bolt holes) like the original fittings have, so I had to buy a special end mill (I with the proper radius) to spot face the bolt holes once I through-drilled everything in the horizontal stab jig I built....

http://www.havasreti.com/images/attach_fittings.jpg

Bela P. Havasreti

51fixer · **Posted:** Tue Nov 06, 2012 9:32 pm

The cross tube for the MLG Uplock Release Tube is bent on one end so I got a new one which came in a cool NAA box-

Opening it the tube was covered in preservative and wrapped.

After cleaning in the solvent tank the Insp stamp shows for the 1st time since Jan 1948.

snj-5 · **Posted:** Tue Nov 06, 2012 10:01 pm

Neat! Some day those 60+ year old NOS boxes will be collector's items in their own right (if they aren't already so).

Bela P. Havasreti

51fixer · **Posted:** Tue Nov 06, 2012 11:45 pm

Opened up the 1st Horizontal to look over a couple areas of concern-

Skin assy removed-

I believe this skin had been removed by the Navy, probably at O/H in 44.
Found the rib inboard of the end rib to have a slight buckle, angle hitting the cutout and a rivet hole cracked-

DH82EH · **Posted:** Wed Nov 07, 2012 4:41 pm

When it comes time to lay that skin back down, or a new one if required, will you have to work from the centre out, in order to buck the rivets?

I also wonder if the Burmese Spitfires will be covered in the same preservative

Great thread Rich. Thank you.

Andy Scott

51fixer · **Posted:** Wed Nov 07, 2012 5:23 pm

DH82EH wrote:

When it comes time to lay that skin back down, or a new one if required, will you have to work from the centre out, in order to buck the rivets?

I also wonder if the Burmese Spitfires will be covered in the same preservative

Great thread Rich. Thank you.

Andy Scott

You work from the fwd spar aft reaching under the skin as long as possible.
Then you get people with skinny arms and go through the aft spar access holes for the rest of the ribs.
The 2 sides and the rear spar are easy with access from the outside with squeezers for the most part.

DH82EH · **Posted:** Wed Nov 07, 2012 5:45 pm

I guess that's why you're training your boys!!

For their skinny arms.

You must look back at this thread as a kind of family album. Nice gig!

Andy Scott

51fixer · **Posted:** Thu Nov 08, 2012 10:28 pm

My son removed a few more pieces as a few spots of corrosion are on the ribs.
We'll start with glass bead blasting and see if the ribs are worth saving.

Removing the leading edge-

Rib removal-

Dark areas on the lower flange are some of the light corrosion concerns-

Ribs removed-

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