C 140 lANDING GEAR BOX CRACKS - REPLACEMENT?

[ndtom]

JUST ACQUIRED A '47 C 140. 8 LANDINGS AND 3 WEEKS OF OWNERSHIP, IN FOR FIRST GOOD ANNUAL. FOUND SIGNIFICANT CRACKS IN LANDING GEAR BOX AREA, AND EVIDENCE OF PREVIOUS REPAIRS. Would appreciate any CORPORATE KNOWLEDGE or thoughts on available replacement box and associated parts PROJECT. A BIT worried about reconstruction of deep airframe component...., WOULD LIKE TO FIND FOLKS WHO MAY BE ABLE TO TAKE ON AND FINISH PROJECT, IN MY LIFETIME, Thanks, Tom

[edidin]

Pics if you have them would help. Sometimes cranks can be repaired while gear boxes are in aircraft - for example welding of the little gussets if they have cracked. Still requires some de-riveting of the floor skin, but less invasive than gear box replacement which is major surgery.

[8368]

I recently acquired a storied ‘47 Cessna 140. Real nice airplane but it has Gearbox cracks found during a detailed inspection.

I’ve gotten to where we have the wings, struts and gear legs removed.

Today we removed the Seat Pan. It still looks challenging to get in to where the Gearboxes are.

Anyone out there familiar with either Gear Box removal techniques or welding Gearbox cracks in place?

Ric W

[6597]

You don't want to weld cracks with the gearbox in place. Past owner tried what appeared to be stick welding some cracks thru the hole where the strut enters. Was a real kluge job not to mention the potential damage to adjoining aluminum bulkheads.

My gearbox when I removed it was easily tig'd and then we put a rosebud flame to it to normalize it. Bead blast and chromate. Welding was the easiest part of the repair.

When we re-installed the gearbox only one rivet wouldn't go into place. We also used some huck fasteners in some difficult spots. Our biggest problem was bulkhead damage that had to be addressed with reinforcements as there were no rear bulkheads to be found back in 2003.

gearboxweldingA.JPG (26.31 KiB) Viewed 4072 times

bulkheadrepair1.JPG (51.03 KiB) Viewed 4072 times

bulkheadbracingA.JPG (52.49 KiB) Viewed 4070 times

[8368]

Thanks Dave for the advice.
We finally got the GearBoxes out. Now to get them welded.
I have similar cracks on the aft bulkhead where you installed a repair. Looks pretty darn good.

Curious; what fasteners did you use to replace the high shear NAS178-6-2 and NAS178-6-4 steel rivets?

-Ric W

[8368]

Also Dave, did you remove the Floor Panels under the Rudder Pedals to get to the fwd side of the Gearbox fasteners?

Ric W

[6597]

Ric,

I pm'd you my 337 that should help you figure out what we did back in 2003. IIRC we did remove the left floor panel to gain access, I see that I chromated it afterwards. And I just finished painting the fuselage the previous year, had to go over rivet heads on the outside with a fine brush for touchup........D

[8368]

Thanks Dave. Quite helpful. My poor baby has been thru a lot in its life including rough landings. Gearboxes are out and will be welded.

Several locations show signs of trauma in the form of deformation and cracks.

Will pattern my repairs and documentation along the lines of what you provided.

Again, thanks.

-Ric W