Flat pitch Hartzell

Deweyclawson · #1 12-28-2018, 07:42 PM

I recently purchased a 2012 RV10, 390 hrs, TTSMOH, TT airframe. IO540, Blended Airfoil Hartzell CS, MT prop controller.

I flew it home from TX, 7hrs, and Tue flew about an hour. Wed I took a puppy to just S of Albany, NY (2 hrs) and another guy took her on to her furever home in Maine. I took off on the return leg and was level at 8,000 IFR, just on top of the clag, about 63% power, 22inches, 2100rpm, or so and about to lean and the rpm ran away. 2700rom.

Yanked the throttle back, could not change the rpm with the prop lever. Prop had gone to flat pitch. Next thing I looked at was oil press. All OK. Started immediate turn back toward lower ground (was over the Catskills) and better wx and said the magic word....EMERGENCY. Landed at Kingston-Ulster airport, NY.

Found the only mechanic on the field. He was in the middle of 2 week vacation but came in to help me. We talked to Penn Yan and to NE Propeller Service. They gave us some ideas to look at.

1. Linkage was connected and worked OK ran eng and prop was not controllable.
2. Moved the prop by hand and each blade moved OK. rotate blades. OK
3. Stick a paper clip in the zirk fittings on the prop. Only grease in there.. OK
4. Removed the oil filter and inspected it for metal shavings. Looked OK. Front main bearing hasn't spun and blocked the oil passage.
5. Removed prop governor and drove 3 hours to New England Prop Service. They tested the governor and it checks OK.
Drove home 10 hours.
Out of ideas.

HELP!!!

Dave H. · #2 12-28-2018, 08:16 PM

I'll bet it was cold up there. OAT? Oil temp? Oil type?

rocketbob · #3 12-28-2018, 08:48 PM

This is your next step:

https://www.lycoming.com/sites/defau...0Procedure.pdf

Let me know if you need the test plate. I have one I would be more than happy to loan you.

BobTurner · #4 12-28-2018, 09:32 PM

The prop did not ?run away?. 2700 rpm is the normal red line. If the governor failed in cruise you would have seen a lot higher rpm. Somehow the governor setting slipped to the high rpm stop.

rocketbob · #5 12-28-2018, 10:07 PM

Quote:

Originally Posted by BobTurner

The prop did not ?run away?. 2700 rpm is the normal red line. If the governor failed in cruise you would have seen a lot higher rpm. Somehow the governor setting slipped to the high rpm stop.

Not necessarily.

The governor is nothing more than a pressure regulator. Oil pressure output from the gov increases blade angle, thus lowering RPM. If there is a large leak between the gov and the piston in the dome, or if there's not enough oil going into the gov, then the big spring in the dome will push the piston into the low pitch stop.

The test in the SI determines either of two things. 1. Excessive leakage after the governor, or 2. not enough oil being supplied to the governor. Since the governor checked out fine, possible failures are the big plug in crankshaft is leaking, one of the o-rings in the prop piston has failed, or there's not enough oil getting to the governor due to a blockage or there's a leak upstream.

BobTurner · #6 12-28-2018, 10:44 PM

Quote:

Originally Posted by rocketbob

Not necessarily.

, then the big spring in the dome will push the piston into the low pitch stop.

m.

If the stop has been properly adjusted to barely allow 2700 rpm at zero speed, then at cruise if you?re up against the stop you?ll see well over redline.
It could be a coincidence-system just leaky enough to get 2700 rpm, but no more- but that?s quite a coincidence.

Deweyclawson · #7 12-29-2018, 05:12 AM

"I'll bet it was cold up there. OAT? Oil temp? Oil type?"
Phillips 20w50, 25 hrs on the oil, Reiff pre heat, sump, cyls and oil cooler heated for 2 hours before first start. temp on gnd was about 35F. 120F befoe run up. 2 hrs at 9,000ft with everything in the green. 30 min to refuel then t/o. Cold oil could not possibly be an issue.

"If the governor failed in cruise you would have seen a lot higher rpm. Somehow the governor setting slipped to the high rpm stop."
New England Prop Services tested the governor and could find nothing wrong. I have a hard time believing the gov fixed itself.

"then at cruise if you’re up against the stop you’ll see well over redline."
But I had the throttle pulled back to about 22" MP. I did not spend a lot of time looking at the tiny rpm gauge on the EFIS. I just saw it was way higher than it should be and pulled the throttle back. It may have been past redline, but I wasn't going to stare at it long enough to figure that out.

I think RocketBob is correct, we need to determine if oil pressure is correct to the governor.

Bob, email sent.

rvbuilder2002 · #8 12-29-2018, 08:09 AM

Quote:

Originally Posted by Deweyclawson

I think RocketBob is correct, we need to determine if oil pressure is correct to the governor.

I agree.
And if you aren't sure what the max. RPM was, you should also download the EFIS data and confirm it didn't exceed the limit that requires a propeller inspection.

rocketbob · #9 12-29-2018, 08:46 AM

Quote:

Originally Posted by Deweyclawson

I think RocketBob is correct, we need to determine if oil pressure is correct to the governor.

Not only to the governor, but from it as well.

Full Throttle · #10 12-29-2018, 10:58 AM

With the governor off and looking at the governor base pad, you should be able to put air pressure in the bottom left oil hole in the governor base pad of the crank case. If the prop changes pitch, the prop is probably OK. If it does not change pitch, then listen for air leaking into the crank case. If the air is rushing threw the back freeze plug in the crank, you will hear it. If the freeze plug hass come loose, you'll have to pull the prop and replace it with a new one. Special tool needed to do it right.