Prop went full pitch on runup...

[FloridaMan]

Post annual run-up by IA. He called me and set the prop went full pitch and the engine wouldn't go past 2000 RPM. He pulled the prop and governor and sent it off. Has anyone experienced this? My best guess is an obstruction in the governor causing this, but also, this would be a bad thing to have happen on my 2800ft runway if she decided to feather halfway down my takeoff roll. 

[carusoam]

1 hour ago, FloridaMan said:

Post annual run-up by IA. He called me and set the prop went full pitch and the engine wouldn't go past 2000 RPM. He pulled the prop and governor and sent it off. Has anyone experienced this? My best guess is an obstruction in the governor causing this, but also, this would be a bad thing to have happen on my 2800ft runway if she decided to feather halfway down my takeoff roll. 

Important to note….

Full pitch fine…  full pitch coarse…?

 

Are we discussing Rocket?  We must be…

Rocket props fail in full feather mode, when the Gov’s gear pump fails to deliver oil pressure to the prop…

Great for engine out, at altitude…

Horrible for gov failure during the first 1k’ climb…

Could be gov valve, gov pump, or an internal oil leak draining the pressure back to the case…

Find Cody… he is both our prop guy and Rocket owner… @Cody Stallings

 

The more you think about failure modes… the better that four blade prop starts looking…. 

 

My M20C had a simple internal oil leak, misplaced shaft seal… it failed the ground run-up test, prop never came off the high pitch stops… engine can overspeed depending on how well the stops have been placed… pilot can control the rpm with MP, it won’t overspeed, but it won’t deliver a lot of power either…

Old plane issues….   fortunately, the run-up is pretty good at ferreting out these issues moments in advance of pushing the throttle in for T/O….

Good luck with your next steps…

I’m only an ordinary Private Pilot, not a mechanic…

Best regards,

-a-

[Will.iam]

It would help to update your profile with type of airplane you have or include it in your post. As committed above if your airplane is not modified by rocket engineering then this would be a perplexing issue. 

[MikeOH]

Do I understand correctly that your A&P sent off your prop and gov without calling you first?

[carusoam]

9 minutes ago, Will.iam said:

It would help to update your profile with type of airplane you have or include it in your post. As committed above if your airplane is not modified by rocket engineering then this would be a perplexing issue. 

Will,

The challenge may be… some people have more than one Mooney… 

Imagine your slow plane is an M20F….  
 

We have one MSer with two Rockets…

and one MSer whose slow plane is a rocket…

 

Go MS!

Best regards,

-a-

[Austintatious]

16 minutes ago, carusoam said:

 @Cody Stallings

 

The more you think about failure modes… the better that four blade prop starts looking…. 

 

 

I dunno, I have thought a lot about this and I am not certain that if I went with a 4 blade prop that I would not still prefer the full feathering.  Now, keep in mind that I have been in a crash after takeoff and have experienced a Prop governor malfunction in the Mooney Rocket... though it was just erratic RPM.

Yes, we can certainly think up scenarios where a feathering prop would not be preferable... this of course being a prop governor failure between insufficient runway remaining ahead and about 500-750 feet AGL. 

So yes, in that one particular scenario, I would rather the prop not feather.  The good news is that if you find yourself with that emergency, with a feathering prop, at least you have a good glide ratio and can perhaps pick your crash better.  A feathering prop also allows "the impossible turn" to be successful at a lower altitude.  I suspect as low as about 300-400 feet where you might need 750 without a feathering prop, YMMV.

However... When I think about ENGINE failure after takeoff, well, you lose thrust no matter your prop... so feathering is preferred.

And, should the engine fail in cruise, certainly a feathering prop is preferable.  Now you may be thinking, what if the prop governor fails in cruise?  If that happens, again, at least you have  good glide ratio and can likely make an airport safely.

Consider an engine failure during approach... With a full feathering prop, you can still make the runway on a 3 degree path.  Without a full feathering prop you cannot.  And if you have a full feathering prop, and the prop gov fails, at least you can make the runway.

Just my .02

 

[carusoam]

Thanks Austin,

The key thing here…

Is for everyone to know their prop’s gov as well as you do….   
 

We have seen a few govs fail on the ground around here…

and probably a couple in flight, including the prop control failures… knob falling apart on an Ovation…

Fortunately, no disasters that I can recall…

 

Are there two Rockets in your stable?  
 

That would make your input worth $0.04….   

Best regards,

-a-

[EricJ]

3 hours ago, FloridaMan said:

Post annual run-up by IA. He called me and set the prop went full pitch and the engine wouldn't go past 2000 RPM. He pulled the prop and governor and sent it off. Has anyone experienced this? My best guess is an obstruction in the governor causing this, but also, this would be a bad thing to have happen on my 2800ft runway if she decided to feather halfway down my takeoff roll. 

A post-annual runup failure on something that was working fine pre-annual is most likely maintenance related rather than an equipment failure, I'd think.   Something may have gotten knocked loose or not put back properly.   Was the prop taken off during annual by any chance?

 

[Austintatious]

18 hours ago, carusoam said:

Thanks Austin,

The key thing here…

Is for everyone to know their prop’s gov as well as you do….   
 

We have seen a few govs fail on the ground around here…

and probably a couple in flight, including the prop control failures… knob falling apart on an Ovation…

Fortunately, no disasters that I can recall…

 

Are there two Rockets in your stable?  
 

That would make your input worth $0.04….   

Best regards,

-a-

I agree, everyone should know the prop type they have and fly accordingly. 

I do own two Rockets, however I only own half of each, so it looks like I am back down to $0.02   !!

[A64Pilot]

On 8/19/2022 at 10:00 AM, Austintatious said:

I agree, everyone should know the prop type they have and fly accordingly. 

Pretty easy, if when walking up to the airplane if the props feathered, then if you lose oil pressure it will feather, cause you lose pressure on shutdown.

Garret’s and some Pratt’s on seaplanes will have start locks. So they won’t be feathered before start but do auto feather in flight if the engine quits.

Every turbine I’ve flown except one will feather on loss of oil pressure, so of course that was the one I had an engine failure on, a windmilling prop on a turbine is an enormous amount of drag.

Oh, some, most maybe aerobatic props go to high pitch on loss of oil pressure, that keeps the engine RPM from going through the roof if you lose pressure in a routine.

This Reno racer lost pressure to the prop governor, so the pitch went flat, Engine seized, but before it did the RPM went so high the prop exploded. Be sure to listen to the sound.

 

[Austintatious]

12 hours ago, A64Pilot said:

Pretty easy, if when walking up to the airplane if the props feathered, then if you lose oil pressure it will feather, cause you lose pressure on shutdown.

Garret’s and some Pratt’s on seaplanes will have start locks. So they won’t be feathered before start but do auto feather in flight if the engine quits.

Every turbine I’ve flown except one will feather on loss of oil pressure, so of course that was the one I had an engine failure on, a windmilling prop on a turbine is an enormous amount of drag.

Oh, some, most maybe aerobatic props go to high pitch on loss of oil pressure, that keeps the engine RPM from going through the roof if you lose pressure in a routine.

This Reno racer lost pressure to the prop governor, so the pitch went flat, Engine seized, but before it did the RPM went so high the prop exploded. Be sure to listen to the sound.

Unfortunately, I got to experience what this is like shortly after takeoff in a Piper meridian... Engine rolled to idle and that big ol prop dragged me back to terra firma real fast!.

[Parker_Woodruff]

On 8/18/2022 at 12:02 PM, FloridaMan said:

Post annual run-up by IA. He called me and set the prop went full pitch and the engine wouldn't go past 2000 RPM. He pulled the prop and governor and sent it off. Has anyone experienced this? My best guess is an obstruction in the governor causing this, but also, this would be a bad thing to have happen on my 2800ft runway if she decided to feather halfway down my takeoff roll. 

Happened to me in an M20R.  Cycled prop on runup and it wouldn't go back to low pitch when advancing the prop lever.  The governor had just been overhauled.  I think it was a snap ring to blame.

[A64Pilot]

7 hours ago, Austintatious said:

Unfortunately, I got to experience what this is like shortly after takeoff in a Piper meridian... Engine rolled to idle and that big ol prop dragged me back to terra firma real fast!.

P3 pressure line leak? I know several fuel controls had cracking bellows problems

[Austintatious]

On 8/21/2022 at 3:24 PM, A64Pilot said:

P3 pressure line leak? I know several fuel controls had cracking bellows problems

Cause was never determined.