Prop Hunting and Surging

MarkC · #1 12-08-2006, 06:14 AM

Hi All,

I just started flying my RV-7 (first flight was on Sunday 12/02). It flies great except for a little issue I'm having with (I think) the prop governor. At certain speeds the RPM's vary by up to 100 up and down from where the prop is set. it smooths out after a while and flies just fine but when I change power, off it goes again. Anyone had anything like this happen? The governor is an MT from Van's. The only real advice I've had thus far is "pull it off and send it back to van"s". As I'm only about 7 hours on the plane now the idea of taking the plane down for a month while Van's gets around to shipping me a new one is not too appealing.

Just wondering if there is anything I'm missing.

Thanks,

Mark
RV-7 - N234C - 7 Hours and counting.
http://websites.expercraft.com/markc

sjhurlbut · #2 12-08-2006, 09:30 AM

I know the solution. 100 hours now and I'm on my third governor.

What you need to do is look at the serial number on the governor. It must end in -C or -D. Yours is probably -B.

I have -D in mine and its perfect. Talk to Jeurgen at MT in Florida. MT was fantastic helping me sort this out.

Don't talk to Vans about it. I relayed the info to them but they were unfamiliar with the problem. Deal directly with MT.

In the meantime MT and I decided the airplane was ok to fly while waiting for the new governor. You'll notice if you pull back the power a bit after about 500 AGL, it will do away.

Steve
RV7A

gmcjetpilot · #3 12-08-2006, 01:20 PM

Third time I have heard of prop rpm issues with a MT gov. Woodward govs seem to not do this, last longer and are rebuild-able. I am told MT govs are worn out after getting to TBO from a prop shop? Can't verify that. Not saying they are bad, but they are more lightly build. Brand new Woodwards are priced too high, so the MT is an attractive buy.

grjtucson · #4 12-08-2006, 01:42 PM

I spoke with Bob Honig at Copperstate about Ameritech Industries in Redding - they do lots of engines and props, Superior, ECI, MT, Hartzell, they pretty much cover the spectrum. Bob appeared to be extremely knowledgeable.

He very stridently recommends a PCU 5000 governor, PMA'd, shorter and more compact than MT, 3 year warranty or engine TBO, $1,450 new. They claim that is less than most overhauls.

I'd sure look into this if I were you. http://www.americanpropeller.com/

George

MarkC · #5 12-08-2006, 02:39 PM

Quote:

Originally Posted by sjhurlbut

I know the solution. 100 hours now and I'm on my third governor.

What you need to do is look at the serial number on the governor. It must end in -C or -D. Yours is probably -B.

I have -D in mine and its perfect. Talk to Jeurgen at MT in Florida. MT was fantastic helping me sort this out.

Don't talk to Vans about it. I relayed the info to them but they were unfamiliar with the problem. Deal directly with MT.

In the meantime MT and I decided the airplane was ok to fly while waiting for the new governor. You'll notice if you pull back the power a bit after about 500 AGL, it will do away.

Steve
RV7A

Ahh, that sounds exactly like the issue I'm seeing. I'll give the guy at MT a call and check the serial number next I'm down there.

Thanks for your help,

Mark

gshipman · #6 12-08-2006, 11:59 PM

So, with almost 50 hours on the plane my prop started hunting and surging as well, I was very lucky to be at an airport that has a prop rebuild shop on site. Apparently they heard my plane going around the pattern and said they hadn't ever heard one surge so much. This has never been an issue before but today it was quite apparent. I am working with one of the MT distributors who was very helpful. I will let you know how this goes, I hope this is a simple issue of replacing the governor but it could be something else.

- Galen

scard · #7 12-09-2006, 08:00 AM

This thread is starting to concern me. I just installed an MT governor with a 'B' serial number on my 320. What is MT saying about these. Are they freely swapping them out or only after we see +-300 rpm (dangerous in my opinion)?

13brv3 · #8 12-10-2006, 06:13 PM

You guys have my attention as well. My plane only has 10 hours on it, and the "B" MT gov has worked great so far. Is this something that will just start happening one day? Are these "recalled" by MT, or just when you have problems?

Thanks,
Rusty (used to be happy to get a B)

Captain_John · #9 12-10-2006, 06:22 PM

Quote:

Originally Posted by grjtucson

I spoke with Bob Honig at Copperstate about Ameritech Industries in Redding - they do lots of engines and props, Superior, ECI, MT, Hartzell, they pretty much cover the spectrum. Bob appeared to be extremely knowledgeable.

He very stridently recommends a PCU 500 governor, PMA'd, shorter and more compact than MT, 3 year warranty or engine TBO, $1,450 new. They claim that is less than most overhauls.

I'd sure look into this if I were you. http://www.americanpropeller.com/

George

See also www.pcu5000.com for the company website.

CJ

sjhurlbut · #10 12-11-2006, 06:44 AM

Quote:

Originally Posted by 13brv3

You guys have my attention as well. My plane only has 10 hours on it, and the "B" MT gov has worked great so far. Is this something that will just start happening one day? Are these "recalled" by MT, or just when you have problems?

Thanks,
Rusty (used to be happy to get a B)

No they are not "recalled" and it doesn't happen to all -B mods. If you get surging however call MT and get it swapped out. The current mod is -D. This is what I'm using, and its perfect now.

Steve
RV7A