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N12055 SN79 Coming Back
http://thorp18.com/thorpforum/viewtopic.php?f=36&t=7876
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Author:  jtwigg [ Thu May 25, 2017 7:52 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Haha, I'm a little slow! :o :-\

Author:  rhartmaier [ Fri May 26, 2017 11:18 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Best de-greaser in the world is Dollar Tree "LA's Totally Awesome Oxygen Orange". The just plain "LA's Totally Awesome" is pretty good also. I use it to de-grease the drive train on my road bike.

Author:  jtwigg [ Wed May 31, 2017 7:10 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Thanks for the tip - I'll go get some and try it out!

Author:  jtwigg [ Wed May 31, 2017 7:37 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Some of the work done the week:
* Went to Annapolis and Washington DC over Sat/Sun, so no work done until Memorial Day when we got back
* Checked the condition of the steel inserts inside the O-290G (converted to an O-290D or D2) engine mounts and found zero rust on this 43-year old aircraft.
* On the main gear A-frame, I sanded the old brown paint off until I got down to primer
* I painted the A-frame orange/red to try to match N12055's color
* I found zero rust on the A-frame's steel inserts at the lower gear attach points
* I began to replace the rubber gear shock inserts and washers that I got from Cubes
* I polished the oil breather tubes with Rolite aluminum polish with Amazing results.

Attachments:
File comment: Zero rust in O-290G steel inserts.
20170529_111317.jpg
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File comment: Sanding good enough to start painting
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File comment: The painted A-frame
20170529_170713.jpg
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File comment: Zero rust in the main gear steel inserts - nice!
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File comment: The finished tube looked just like the non-polished tube before I started.
20170529_220633.jpg
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Author:  James Grahn [ Wed May 31, 2017 8:00 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Wow. Lotta love! Nice job.
Cubes

Author:  Rich Brazell [ Wed May 31, 2017 8:45 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Attention to detail ! ;) Looking good ! The hard part is maintaining it to keep it that way ! ???

RB O0

Author:  jtwigg [ Tue Jun 06, 2017 12:08 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Does anyone know how much we're supposed to torque the engine mount and A-frame nuts by? I don't see them in my plans. I'll be ready to reassemble the gear and mount next week. Almost all of the parts are painted. Waiting a full 7 days so that the paint gets chip-resistant.

Author:  bfinney [ Tue Jun 06, 2017 12:35 pm ]
Post subject:  Re: N12055 SN79 Coming Back

AC 43.13-1B section 7-40 - the mechanic's bible.

Author:  jtwigg [ Tue Jun 06, 2017 3:37 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Thanks, Bruce! I do have a copy of 1B and the formula is on p363 I think... I thought that specific torque values would be provided by Thorp for the T-18's engine mount.

Author:  fytrplt [ Tue Jun 06, 2017 6:11 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Rubber mounts (vibration isolators) are NOT torqued to the spec of the size of bolt they are. You will crush the spacer tube. they just need to be snugged up.

Author:  jtwigg [ Wed Jun 07, 2017 7:16 am ]
Post subject:  Re: N12055 SN79 Coming Back

HI Bob, thanks for the clarification and reminder. I wasn't clear - I meant the 6 AN4 bolts that bolt the ring to mount tubes and the bolts for the A-frame. Thanks for having my back :) !

Author:  jtwigg [ Sat Jun 10, 2017 1:34 am ]
Post subject:  Re: N12055 SN79 Coming Back

Some of the work done this past week:
* Stripped, primed, and painted the engine mount tubes and ring
* Polished the other oil breather line with Rolite
* Cleaned old paint overspray from the firewall and around the landing gear A-frame attachment points
* I decided NOT to polish the firewall with Rolite because it's already good enough and I want to be flying N12055
* Taped the engine in preparation for cleaning

Tomorrow (Sat), I'll be cleaning the engine. What started out as a small project to remove the engine to change the shock isolation mounts, of course became a larger project to remove and replace oil drain line rubber tubes and intake pipe rubber tubes, clamps, etc.

I'm starting to see some light in this tunnel. Got some great advice this week from forum members about torque values for engine mount and A-frame bolts. (Shock mount bolts are not torqued-just snugged as I was reminded). I have a big list still, but I think I can get N12055 out to the airport right after Oshkosh and have it ready for its condition inspection.

Attachments:
File comment: The second oil breather tube amazingly restored with Rolite polish
20170604_175725.jpg
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File comment: Stripped the engine mount parts and checked their welds visually
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File comment: Engine and painted parts are hanging from the ceiling
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File comment: The firewall needed just a little cleaning to look great after 43 years.
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File comment: Engine almost ready for cleaning tomorrow
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Author:  jrevens [ Sat Jun 10, 2017 3:32 pm ]
Post subject:  Re: N12055 SN79 Coming Back

John,

IMHO, you should tighten the engine mount bolts that go throught the center of the Lord mounts to standard torque values for that size bolt. The spacers, if made of the proper material, are 4130 N tubing. They should not be deformed from those levels of tightness/torque. If you want to confirm that, just take a bolt, washers & nut & tighten them on a spacer to those values of torque. I've honestly never seen any deformation occuring on mine after tightening to standard torque values. Also, be sure to take into account the "running torque" of the assembly before contact occurs, and add that to the standard torque value for that size bolt when you are setting your torque wrench. If others disagree with this I'd like to hear about it.

Author:  jtwigg [ Sat Jun 10, 2017 5:16 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Hey John, you bring up a good point. I'd be interested in what the consensus is too.

Also, when I bought it, my plane had drilled shank bolts and castellated nuts on each of those 4 bolts. What do most people use? I bought both undrilled and drilled bolts and 363 and castle nuts just in case. I have concerns about 365 nuts in the engine compartment.

Author:  Rich Brazell [ Sat Jun 10, 2017 6:16 pm ]
Post subject:  Re: N12055 SN79 Coming Back

Mine likes castellated nuts and drill bolts/carter pin . :P

RB O0

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