Thorp Air Command - T18.net

Haha, I'm a little slow!

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

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.

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

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

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.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Wow. Lotta love! Nice job.
Cubes

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

RB

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.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

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

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Bruce Finney
N18JF T-18C #262
Yelm, WA USA

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.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

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.

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Bob Highley
N711SH
SN 835
KLAL

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 !

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

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.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

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.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

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.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Mine likes castellated nuts and drill bolts/carter pin .

RB