Urgent A&P Help Near KDVT

[spurlockda]

Hi everyone,

Weird thing happening while I am going through my Initial Transition course. I bought N937DY up in Canada and when the Canadian Instructor and I flew down to KHND, we cruised nonstop at 17k with no issues whatsoever. Heat and pressurization were wonderful.

The plane sat on HND’s flight line for about two months while I wrangled with the Insurance cartels and finding a Initial/Transition school.

When the Initial school instructor and I flew to KDVT, we noted manifold pressures sub nominal for a turbo/pressurized aircraft. We flew it again the next day in a meticulous test profile and (here’s the weird part) both MPs are low to the point of seeming like a normally aspirated plane. Take off pressures are normal but as we get up to and past 10k, the MPs don’t keep up with the climbs and the cabin pressures don’t seem to keep up either. CHTs, TITs and etc are good; engines are leaned properly and everything else is conducted in accordance with the current POH.

Does anyone out there know of a great 337 A&P in the Phoenix area. We have elected to slow down or suspend the Initial/Transition training until we can get the A&P to check things out.

Please help - I want to fly my airplane solo!!!!!!!!

[hharney]

Check with Falcon Field in Mesa. They likely will have some experience.

Sounds like it's the waste gate sticking open. If the airplane has sat for a while it will need to mouse milk lube

[spurlockda]

Originally Posted by hharney

Check with Falcon Field in Mesa. They likely will have some experience.

Sounds like it's the waste gate sticking open. If the airplane has sat for a while it will need to mouse milk lube

Thanks Herb!

The weird part is that it is both engines. Both MP readings are abnormal. I suppose both waste gates could be sticking. I’m sure the plane is experiencing environmental shock since it went from always hangared up in cool British Colombia to out in the hot sun of Henderson NV.

My first guess was something wrong with the gauge but when we tested the various altitudes and there was definitely a performance degradation.

Take offs are great even at the hot & high altitudes of Prescott and Phoenix but once we get up to 10k and beyond the performance hit becomes evident.

I agree with the instructor about not doing any single engine practice until we get the problem fixed but the one time we did, it was eye-opening. 😳

[JimC]

I had that happen to a twin turbo plane (both wastegates stuck open at the same time after an extended sit.)

I didn't get off the ground - it showed up on the takeoff roll.

[general]

Herb is about 100% righ,
t you need to get it coated with mouse milk lubricant so the gages work properly. I've seen this problem, and the plains been setting in a dry climat like Phoenix
Good luck but don't let them try to sell you a couple of new turbos, check the wastegates first.

[spurlockda]

Thanks guys,

Do y’all think if is rust forming while it’s sitting? I’ll try the mouse milk if I can find some. Plus I’ll head over to Falcon.

I didn’t come down with tools so about the only thing I can do is beat ‘em with a big rock 🤭😂

[spurlockda]

Well, I liberally applied the mouse milk I found to the butterfly shaft ends and got my Initial nstructor ready for another test flight.

Then Murphy decided to kill my Gill battery!

Now the mouse milk has had time to soak 🤬

This is what the Instructor wrote down on the last flight. I thought he wrote down more data???

[ Manifold Pressures with cowl flaps open;

RPM top of green:
11k 30 33,
13k 30 30,
14k 30 30,

RPM to 2450:
14k 25 25 ]

If we can fly again, is there anything we should record better or use different aircraft configurations (like crowl flaps open/closed; cabin pressure on/off; etc?

[spurlockda]

Hi everyone,
Still looking for an A&P. Called virtually every A&P in the Phoenix valley based upon mechanics lists from the FSDO, A&P friends of friends, spot sightings of mechanics working on planes and everything else I could think of.

Now I have to broaden my search to other states. I’m willing to get a ferry permit from the FAA if required but I don’t really want to fly across the middle of the country.

Does anybody have any recommendations for competent, not-insanely-busy-with-month-long-waiting-lists, maybe willing to travel, Super 337 pressurized A&Ps?

Thanks in advance!
Dave

[dan1000]

Forgive me if I'm misinterpreting. But it seems like you just need a mechanic who is familiar with the engine (and turbo), not particularly a Skymaster mechanic. If I'm correct, finding someone to work on your engines shouldn't be too hard.

Those smarter than me might be able to speculate whether a problem with the pressurization system might cause the MP gauges to read wrong (though I don't think so).

Throttle cable slippage? Can you make full rated power on the ground?

Sorry I'm not able to be more helpful.

Dan

[dan1000]

If you don't mind a flight to San Diego, Advanced Aircraft just did a very thorough annual (that acted as a pre-buy) of N70S, my new (to me) 1974 Pressurized Skymaster. They are at Montgomery Field (KMYF).

The previous owner paid for the work, but I was very happy with the quality of what has been done.

Dan

[spurlockda]

Thanks Dan,

I’ll give them a call tomorrow.

Dave

PS: I’d like to meet up with you and check out your plane. When and where did you find it? You headed for Oshkosh?

[dan1000]

I posted a plane wanted ad on this forum, and was lucky enough to get a response from N70S's previous owner. I looked at many online, but N70S was by far the best combination of condition/equipment/TSOH that I found.

Not going to Oshkosh, but I will be at the Carson City Airport Fly-In on June 23. Would love to meet up with all 337/336 owners who want to stop in.

Dan

[kbecker]

Did you ever get this problem resolved?

Kevin