Landing gear boxes

[8376]

Pleased to announce project complete and thank you to every for pictures and input.

Below is a quick run down of this that fixed in the process:
-gear boxes - removed and welded, three rounds through NDI and welding, in total 33 crack in welds repaired, most at the level where only NDI revealed them
-forward elevator bell crank replaced with a serviceable donor (was unknown other bearings were that bad prior to this project)
-floor attach points for forward elevator bell crank repaired (was unknown that two of the legs had cracks)
-replaced rudder pulleys that were worn
-found and repaired the dreaded doorpost crack, service kit produced in house based on diagram
-all areas under floor primed for corrosion resistance
-trim actuator attachment bracket (where it attaches to trim tab) removed and replaced (crack found under the bolt)

-dual USB port installed
-hooker harnesses installed
-door lock reinstalled

I have plenty of pictures and will upload a few later. Until the wrapping started coming off the package it was unknown how much was going on due to the years of debris and dirt that had accumulated.

Got it back up on a test flight and felt great

Jimmy

[8292]

I'm likely about to embark in a similar "adventure" in my 1950 140A. Found a few cracks that likely had been undetected for years in both gearboxes. A couple along the angled support, and one in the center of the upper "U" channel beneath the landing gear wedge nutplates. While I think we were leaning toward monitoring said cracks, I found a crack in the forward gearbox bulkhead. It's in the radius where the edge of the bulkhead turns to attach to the exterior skin.

Before I embark on what my IA ballparked as a 200 man hour job I'm wondering if anyone has experience with Cessna engineering or an FAA DAR who could evaluate and determine whether it's something to monitor or needs to come out now.

140BulkheadCrackM.jpg (238.12 KiB) Viewed 4129 times

140GearboxCrackM.jpg (274.44 KiB) Viewed 4129 times

140GearboxCrack2M.jpg (177.08 KiB) Viewed 4129 times

Finally, as I'm expecting that this is going to happen, for those that have done this, what have you done for jigs to keep the fuselage straight with the seat pan, and both the top and bottom of the gearbox bulkhead assembly removed?

Thanks.

[klyde sessna]

There is a good thread with pictures on this issue on the Cessna 120/140 Club Facebook page, if you have access to that.

[2066]

Here's a link to an excellent "gear box" related "documentary" with great photos: https://www.google.com/url?sa=t&rct=j&q ... lscj4JliRL

[8292]

To follow up:

I’ve got my gearboxes and bulkheads out. One of the gearboxes has some cracks in the “U” channel as well as cracks on the welds where the web is attached to the forward and aft faces of the gearbox. Before just ordering a new one from Univair, I wondered about whether its worth repairing, and who the experts are for said repairs. I’m located in the Chicago suburbs, but have access to a flying plane and can travel within economical distances for this.

Lastly, does anyone have a LH Gearbox in good condition they would like to part with?

[a64pilot]

I realize I’m coming into the middle of this thread and apologize if this has already been brought up, but with the extensive welding I guess that needs to be done are you guys “normalizing” the gear boxes after welding? Ideally in an oven.

[edidin]

To follow up:

I’ve got my gearboxes and bulkheads out. One of the gearboxes has some cracks in the “U” channel as well as cracks on the welds where the web is attached to the forward and aft faces of the gearbox. Before just ordering a new one from Univair, I wondered about whether its worth repairing, and who the experts are for said repairs. I’m located in the Chicago suburbs, but have access to a flying plane and can travel within economical distances for this.

Lastly, does anyone have a LH Gearbox in good condition they would like to part with?

Since I'm spending other peoples' money, will ask if you wouldn't just want to get new ones after getting in that deep after 75 years?

[8292]

To follow up:

I’ve got my gearboxes and bulkheads out. One of the gearboxes has some cracks in the “U” channel as well as cracks on the welds where the web is attached to the forward and aft faces of the gearbox. Before just ordering a new one from Univair, I wondered about whether its worth repairing, and who the experts are for said repairs. I’m located in the Chicago suburbs, but have access to a flying plane and can travel within economical distances for this.

Lastly, does anyone have a LH Gearbox in good condition they would like to part with?

Since I'm spending other peoples' money, will ask if you wouldn't just want to get new ones after getting in that deep after 75 years?

As it turns out, I did end up ordering a new one from Univair. A mere $1775...

Now I'm trying to avoid having to spend another $1,000 on the doorpost kit through Univair. Does anyone have a template for the updated doorpost? It's listed in the service kit as part 0409012-2.

Thanks.

[lenny]

Gentleman,
I'm a new member and am looking at a 1947 C-120 to purchase. It has 6600 hours on the air frame has had 10 owners and spent its first 8 years (or so) at a flight school in Oxnard CA. It appears to be in good shape, is owned by an IA and has log books back to the first owner.
However I have been reviewing the cracks thru out the gear box as noted in posts on this site. Some can been seen visually others are in underlying structure and are revealed during disassembly to repair the visual ones. It would not appear that there is an AD to repair the gear box assemblies on either side of the fuselage but repair assemblies are available . Can any of you folks that have had experience with repairs in this area give me a ball park on the price of removing and repairing the left and right gear boxes?
This will be my first airplane purchase and I want it to be a good one.