Landing gear boxes

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8426
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Name: Rick M
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Landing gear boxes

Post by 8426 » Sun Apr 14, 2019 4:15 pm

My 120 has a crack on the edge of a weld on the upper portion of the angle support on the landing gear bulkhead support. Is there any tolerance for this discrepancy? Is there someone in the New England area who has experience with this that could advise me on my options? Thanks in advance for your help.
Rick

529
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Location: Michigan
Name: Victor G
Aircraft Type: C-120
Occupation: Work on airplanes till the cows come home..........they're still out.

Re: Landing gear boxes

Post by 529 » Mon Apr 15, 2019 8:51 pm

I realize you're working/looking down inside a small hole to inspect/see the gear box. Any chance of taking a picture or two? Perhaps including a parts book diagram of where the crack is located? (the reason I wrote that is many customers over the years send me an ultra close up of their defect, but I have no frame of reference, in other words stand back and show me a picture in relation to surroundings)

Several things.

1. Typically when cracks are found they are repaired. It's what "should be done".
2. when you find cracks in difficult to access locations and/or on parts that were installed almost "first" during construction of the airplane(boat, car, house etc) then people tend to "monitor them" due to the complexity or time involved with the repair.

I've know multiple IA's who have "monitored" such cracks over the years and the cracks seldom move.

That being said, if your crack is where the gear leg enters the gear box and is forward or aft of where the "wedges" snug up the leg, then I would say unfortunately the gear box should probably come up.

Let's start with a location or picture.

8426
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Re: Landing gear boxes

Post by 8426 » Tue Apr 16, 2019 5:20 am

Thanks for your response. Through the mirror the crack can be seen at the upper angle support weld.
Attachments
4-12-19 001.jpg
Crack along the edge of the weld
4-12-19 001.jpg (98.86 KiB) Viewed 212 times

8426
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Re: Landing gear boxes

Post by 8426 » Tue Apr 16, 2019 7:17 am

Here's a link to Dropbox that show a removed gear box and I have indicated the proximity of the crack. The file was too large to download here.





https://www.dropbox.com/s/ubmf2zu68yc6g ... 1.jpg?dl=0

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6643
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Aircraft Type: 1946 C140/C90
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Re: Landing gear boxes

Post by 6643 » Tue Apr 16, 2019 8:09 am

gear box.jpg
gear box.jpg (119.13 KiB) Viewed 200 times

8426
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Re: Landing gear boxes

Post by 8426 » Wed Apr 17, 2019 5:21 pm

My primary question to the forum is: Is this 120 considered scrap with the gearbox cracks, or is there an approved procedure that has been published that pertains to this problem? I cannot seem to find any info and request the forum's advice.
Thanks,
Rick

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Re: Landing gear boxes

Post by 8342 » Thu Apr 18, 2019 7:10 am

It appears that the material is steel.

If it is removed I would think a good welder would be able to fix it.

It will not be easy but I would think it do able.

Rick

8424
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Name: Steve H
Aircraft Type: 1950 C140A
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Re: Landing gear boxes

Post by 8424 » Thu Apr 18, 2019 7:50 am

Hi Rick.

"Is this 120 considered scrap with the gearbox cracks..."

No, the cost of repairs will not be equal to the value of your airplane. I have removed a damaged gearbox from a C140, had it repaired, and put it back in. It took a lot of hours and if I would have had to pay for those hours at the going rate of a repair facility, I probably wouldn't have been able to afford it. (I live on a pretty tight budget!) My IA kept a close eye on my work, and then did the paperwork and signed off the repair.

So the question you may actually be asking is: "Can I afford to fix it?" I bought the plane with the broken gear box for 1/3 of what I sold it for after flying it for 300 hours over a 10 year period. You would probably take a pretty good hit if you sold the plane with the damaged gear box. Get with an IA who has experience with repairing these planes and he should be able to give a ball park estimate of the time involved. I bet Victor G, who answered your original post would be great to work with if possible! The actual box repair will be relatively inexpensive...it'll be the coming out and going back in that will cost you! However, if you can do the work yourself, it won't be near as traumatic!

Tough decision time for sure!

Steve

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Re: Landing gear boxes

Post by 8424 » Thu Apr 18, 2019 9:05 am

Rick, is your plane on Barnstormers? If so, nice plane...keep it and fix it!

1946 CESSNA 120 • $15,500 • FOR SALE AS IS • Notice: Two small cracks....

Steve

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Re: Landing gear boxes

Post by 8413 » Thu Apr 18, 2019 10:51 am

Rick,
Out of curiosity, is this the 120 that was for sale on Barnstormers a few months ago in Georgia? If so, did your pre-buy miss the gear box cracks? I only ask because I'm in the market for a 120/140 and am concerned about just how difficult it is to find these cracks during a pre-buy inspection? Thanks
Josh

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