Prop governor won’t cycle on the ground but works fine in the air

[orionflt]

5 hours ago, Shadrach said:

This reads like there were other issues as well. Doesn’t the prop have a course and a fine pitch stop. I understand that a prop will fail to fine pitch if the governor fails which can result in an overspeed. However, 30% past redline is a huge overspeed. I don’t think that is a common failure scenario.

Actually the reduced flow was the only issue, the governor did not have enough flow to compensate for the sudden demand put on it. Engine and governor were sent out intact so they could be examined to determine what the failure was. Continental wanted to know what the issue was in case it was not an isolated incident. 

[Yetti]

What weight oil do you run?

[tigers2007]

Phillips XC 20W-50

[tigers2007]

I just thought of this: when taking off I can hear the propeller "surge" for a moment. I slowly increase the throttle to full on takeoff. I figured it was a wind gust (I've experienced this in the past) as both days I have flown were extremely windy. I don't recall seeing the RPM's go beyond the limits. The Tach fairly new and only has 330hrs on it. I'll not fly again until I get this figured out. I'm reading the Hartzell Propeller Owner's Manual right now and it is pointing the figure at the governor.

[jaylw314]

1 minute ago, tigers2007 said:

I just thought of this: when taking off I can hear the propeller "surge" for a moment. I slowly increase the throttle to full on takeoff. I figured it was a wind gust (I've experienced this in the past) as both days I have flown were extremely windy. I don't recall seeing the RPM's go beyond the limits. The Tach fairly new and only has 330hrs on it. I'll not fly again until I get this figured out. I'm reading the Hartzell Propeller Owner's Manual right now and it is pointing the figure at the governor.

I think I get that sound too, so it might be normal.  I think it's the motor building up speed, but when it hits 2700 RPM the prop blades come off the fine pitch stops, and the sound changes suddenly.

[carusoam]

Wind gust and change of wind direction will send the gov chasing...  the drag on the engine changes so rpms start to change...

PP thoughts only,

-a-

[FloridaMan]

Never experienced runaway prop myself, but I hear that it'll get your attention. Flat pitch prop == increased drag. 10% overspeed of your engine == teardown. 

https://www.lycoming.com/sites/default/files/SB369R Engine Inspection after Overspeed.pdf

[tigers2007]

Call me crazy but I think I’m missing a washer and a nut here...

 

The cable attachment shouldn’t be getting caught up in the mag leads either

 

 

 

Uh oh

 

 

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[Shadrach]

1 hour ago, tigers2007 said:

Call me crazy but I think I’m missing a washer and a nut here...

 

The cable attachment shouldn’t be getting caught up in the mag leads either

 

 

 

Uh oh

 

 

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Welll there's your problem right there...  This looks like a maintenance induced failure.

Edited May 8, 2019 by Shadrach

[Yetti]

Time for a conversation with the last person that was messing with the prop governor.    Good news is looks like you have a VERY easy fix.

[Skates97]

I had a problem shortly after getting my plane where it had been making 2,700 and wasn't anymore. It ended up that the cable had worked it's way up in the clamps and was not going all the way to the stop.

 

[carusoam]

Find a pic of what that is supposed to look like...

Don’t be afraid to buy new hardware for that...

looks like the aged locking hardware is no longer capable of locking...

That is a pic worthy of putting @M20Doc‘s eyes on...  prop control hardware

PP thoughts only, not a mechanic...

Best regards,

-a-

[Guest]

4 hours ago, Shadrach said:

Welll there's your problem right there...  This looks like a maintenance induced failure.

That not a maintenance induced failure, that's "a lack of maintenance failure"

Clarence

[Guest]

5 hours ago, tigers2007 said:

Call me crazy but I think I’m missing a washer and a nut here...

 

The cable attachment shouldn’t be getting caught up in the mag leads either

 

 

 

Uh oh

 

 

Sent from my iPhone using Tapatalk

 

Time for some new AN 742 clamps.  Remove the old clamps from the cable, measure the cable sleeve in 1/16" Each 1/16 is one dash number for the clamp, 5/16" diameter would be a AN742-5 and so on.

Clarence

[Shadrach]

22 minutes ago, M20Doc said:

That not a maintenance induced failure, that's "a lack of maintenance failure"

Clarence

 

18 minutes ago, M20Doc said:

Time for some new AN 742 clamps.  Remove the old clamps from the cable, measure the cable sleeve in 1/16" Each 1/16 is one dash number for the clamp, 5/16" diameter would be a AN742-5 and so on.

Clarence

Given the washers and nut are on the lower clamp, I assume that someone removed it and put the fasteners in place on the clamps during some sort of maintenance. The nut and washers likely vibrated off the upper clamp while the aircraft was being operated. 

Edited May 8, 2019 by Shadrach

[tigers2007]

April 2019 EAA’s Sport Aviation has a great article “Nut Basics” covering what I need to know.





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