I am looking for any members who have done a gear box replacement. We had a nasty incident with a culvert that tore the port gear completely out of the fuselage including large chunks of the belly skins and some damage to the door post.
Specifically I'm looking for what was done on jigging.
It appears that here in Canada a project of this magnitude including the engine tear down can allow me to qualify for re registration in the experimental catagory so it should be an interesting project.
Gear Box Replacement
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
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N170BP
- Posts: 552
- Joined: Mon Jul 22, 2002 7:24 pm
I'm in the middle of a gearbox rebuild/replacement on a
'54 C-180. The Whittman style spring gear on the 170 (and
180) is a marvel in design. When you see it all apart (floorboards
drilled out, belly skins drilled out) you begin to appreciate the
wizardry and simplicity of the design.
All those nice things being said, when the gearbox area gets
tweaked, a bunch of "stuff" has to get drilled out/off to facilitate
repairs.
What we did (with the '54 180) is build a support structure out of
4"x 4" lumber that supports the fuselage from the upper door
frame sills. This way, we were able to drill out both fore & aft
gear-box formers without pulling the wings (the wings are supported
at the outer strut attach point with additional 4" x 4" lumber pieces).
I suppose it depends upon how much deformation occurred as to
whether or not you need to utilize "hard tooling" (jigging) to
rebuild the damage that has occured. In our case, the fore and
and aft gear-box formers were damaged/deformed, the inner
gear box webs were tweaked (upper & lower skin angles had all rivets
sheared off)., but other than that, the damage was (thankfully)
confined to parts that were easily drilled off / replaced.
The fancy answer to your question is to get a hold of a willing
C-170 airframe/owner from which you can build "hard tooling" (jig built off of the gear-box area) providing the damage is, indeed, severe enough to justify such efforts.
I can tell you that if it were up to an insurance company, the '53
180 we're working on would have been junked rather than repaired
(there is a fair amount of labor involed in rebuilding the gearbox
area on one of these birds....).
Bela P. Havasreti
'54 C-170B N170BP
'54 C-180. The Whittman style spring gear on the 170 (and
180) is a marvel in design. When you see it all apart (floorboards
drilled out, belly skins drilled out) you begin to appreciate the
wizardry and simplicity of the design.
All those nice things being said, when the gearbox area gets
tweaked, a bunch of "stuff" has to get drilled out/off to facilitate
repairs.
What we did (with the '54 180) is build a support structure out of
4"x 4" lumber that supports the fuselage from the upper door
frame sills. This way, we were able to drill out both fore & aft
gear-box formers without pulling the wings (the wings are supported
at the outer strut attach point with additional 4" x 4" lumber pieces).
I suppose it depends upon how much deformation occurred as to
whether or not you need to utilize "hard tooling" (jigging) to
rebuild the damage that has occured. In our case, the fore and
and aft gear-box formers were damaged/deformed, the inner
gear box webs were tweaked (upper & lower skin angles had all rivets
sheared off)., but other than that, the damage was (thankfully)
confined to parts that were easily drilled off / replaced.
The fancy answer to your question is to get a hold of a willing
C-170 airframe/owner from which you can build "hard tooling" (jig built off of the gear-box area) providing the damage is, indeed, severe enough to justify such efforts.
I can tell you that if it were up to an insurance company, the '53
180 we're working on would have been junked rather than repaired
(there is a fair amount of labor involed in rebuilding the gearbox
area on one of these birds....).
Bela P. Havasreti
'54 C-170B N170BP
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spiro
- Posts: 193
- Joined: Mon Jan 27, 2003 11:08 am
I've done this a couple times. No special jigging needed. If it's just a gearbox and the upper cabin section's undamaged hang the fuselage from the fwd carry-thru spar. Remove all damaged metal and the replacements should just cleco right into place. If not, you didn't remove all the damage.
It can be done without pulling the engine and wings but these are pretty easy to R&R and you don't have to worry about how much to support them. Most gearbox accidents are going to invole a wing or a prop/engine anyway...
Best advice I can give is to get someone's who's done this before, the more times the better.
It can be done without pulling the engine and wings but these are pretty easy to R&R and you don't have to worry about how much to support them. Most gearbox accidents are going to invole a wing or a prop/engine anyway...
Best advice I can give is to get someone's who's done this before, the more times the better.
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