Thorp Air Command - T18.net

OK...talked with the folks at Custom Aircraft Parts concerning the slip joints that are "frozen." This is what they do to get the critters apart. No, not a hose with cold water !

1. Heat the joints with a torch until it turns red and then lightly tap the joint with a small ball pien hammer. DO NOT over heat the joint past the red color. If you heat it to a yellow color you are screwed ! You may have to repeat this process several times allowing the joint to cool each time. That's what they tell me.

2. Use ZEP Twister penetrant. It's the stuff they use. I looked this stuff up. About $15.00 a can. It may have magical powers, but not sure ? Sure sounds like PB Blaster to me. Again use the small ball pien hammer to "massage" the joint.

3. Mouse Milk penetrant.

4. Last option. Cut off wheel, remove the affected area and attach a new slip joint.

Info straight from the folks that build them.

RB
NX115RX

Thanks Rich,
Apparently I have not been heating it hot enough or banging on it hard enough and not using the proper penetrating goop. I'll have to give it another shot.

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

I would soak the crap out of it for a few days with the penetrant and at the same time rap it with the hammer to help break up any rust or grud between the pipes to allow the penetrant to seep in there and get business done, then heat it. Once you get the beast apart, I would smooth the parts down with some emery cloth and then goop on the copper high temp anti sieze upon assembly. May the Force be with you !

RB

50% acetone and 50% automatic transmission fluid is the best penetrant oil on the planet!

JB

Jeff,
Thanks, I knew that, just couldn't dredge it up out of the archival storage of my mind. Will go home tonight and mix a batch and give it a whirl.

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

After a week and a half of soaking, 50-50 ATF and acetone, and rapping (1 pound ball peen hammer) the pipes have separated without using any heat or a bigger hammer. The Force was with me. Thanks Rich and Jeff.

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

Excellent OB-one-Ka-No-Bee ! Can't say if the Copper High temp anti seize will work on re-assembly (should you try to take them apart again), I put it on my pipes, but they have yet to be taken apart. Worth the couple of bucks for a tube to find out ! The stuff was recommended by Custom Aircraft Parts.

Have you seen YODA ??

RB

Regarding PM on the slip joint. I just got off the phone with Custom Aircraft Products that made my exhaust and he says remove the exhaust every other annual, clean out the slip join and reapply the copper anti seize. They make the joint "slightly" oversize to avoid seizing, but if left to do it's own thing over the years carbon will build up in the joint causing the joint to seize and crack the flanges.

RB

Hey guys,

Let me put a little 'experimental' thinking into this homebuilders category. I've got to run blow-by overboard and like the idea of burning it off in the exhaust. I have an air/oil separator taking in the crankase vent tube, and also the exhaust from a wet vacuum pump. Not having done this before I'll assume the pump would waste a lot of oil if it wasn't returned to the engine, so I'll run the drain back in. The question in my mind is what to do with the separator outlet.

I'm afraid just setting it next to the exhaust might leave drippings in the air stream and still get all over the bottom skin. How about welding a small tube right into the tailpipe? Say about 6 inches from the end. I see RV's with the "AntiSplat" device which does this with a check valve to help evacuate the crankcase. But in my plan I still have the vacuum pump to exhaust. My thinking is that with pump running there will always be positive flow going out, the crankcase really has no net flow (in or out), and so not to worry about exhaust getting into the crankcase. Excess oil or fumes should burn up within the last 6 inches of the tailpipe or be ejected farther away from the skin. Would any residual back pressure from the vacuum pump exhaust be bad for the crankcase?

The original plane this engine came from had two separators in series. One for the vacuum pump, the other for the crankcase. Here I'm going single and trying to put it into the tailpipe. Even if it's a stupid idea, conversations on the thorplist are always good to have.

Any thoughts?

Les Krumel, Albuquerque

I've seen the RV guys drip the oil on the exhaust pipe without welding a fitting. Also there is a allen head pipe plug behind the oil filler tube that some use for a return. It's a bastard to get out.
Bob and I ran our vent down the gear leg inside the gear cover and let it exit just below the bottom of the wheelpant, works great. Be sure you drill a small hole in the hose where it vents at the back of the engine to prevent a vacuum and pulling oil out of the crankcase.

Engine experts say you need about +.3 psi (slight pressure, NO vacuum) on the vent. This keeps the oil and oil mist in the engine. The vent only serves to equalize pressure and prevent any large buildup which will blow the front seal. all that said, don't induce any pressure or vacuum to the vent.

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Bob Highley
N711SH
SN 835
KLAL

In my experience (I have one that has a chronic blow by issue), the breather is a good indication of engine health (sans the aforementioned plane) I like to see what's co in out ur breather. Burnt oil on my exhaust stack is not something I want. Plus it gives you a shady job to do at Oshkosh ... Clean the belly.

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

I have been entertaining the idea of changing my exhaust system out. I was looking at the Custom Aircraft Parts offerings but the picture of the model for the Thorp has a different airbox than mine and I am having trouble deciding what it would like installed on mine. Can someone confirm for me the Custom Aircraft Parts crossover exhaust for the T-18 will work on an O-320-B3B with a horizontal airbox with a forward facing Bracket air filter?

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson

Thorpies,

I've tried for several years now to get John Forsling to make a set of exhaust for my thorp and another one I'm restoring and while I did manage to speak with the man, I have not been able to convince him to get one started. He mentioned three times that he would get going on it right away and still no dice err... exhaust.

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In CowTown USA,
Don D-Day
NX18DD

I have the Custom Exhaust from California . Have you talked to Mary Ann or Clinton the owners ? Clinton knows his stuff and I've toured their facility and they were very helpful with making sure my exhaust system fit perfectly , which it did ! I have the pipes on my 0-360 A2A with the Usher carb heat box P/N 08-01604 from Spruce . No problems at all . CALL THE MAN !

RB