Rocket and Missile Prop Governor Failure Mode

KevinR · October 28, 2015

No need to post the question. I just got off the phone with Rocket Engineering who verified the information. I can have a PM or phone conversation with anyone wanting details of who I spoke with but since this is public forum, I'm not going to list the individuals name.

OFFICIAL WORD: In the event of a governor failure (meaning loss of oil pressure to the prop governor) the prop on both the Missile and Rocket will indeed FEATHER - even with a working engine (the engine will shortly quit as well as we learned from Erik's test).

So, the true danger zone is a governor failing at takeoff or very low altitude, as then you are in a 16:1 glider a few hundred feet off the ground. Takeoff, get to 700+ feet, more likely 1000 feet AGL as fast as possible so in the event of a governor failure (or engine failure) you can make the impossible turn and land. The good news is that you're in an airplane with a full feathering prop.

The reason for this feature is due to the setup taken from a twin Cessna (which Rocket used as a blueprint for the setup - either the 340 or 414). They had to make it feather or the flat pitch prop at failure would have been a 1:1 glide ratio (or something like that - huge amount of drag). This way, should your governor die at altitude, you'll be a glider with a 16:1 glide ratio and hopefully miles of options to find a suitable landing destination.

So Erik, your change is that you no longer get a full feathered prop, and thus slightly lower your glide distance, but your airplane weighting balance is better with 30 pounds off the nose and a four blade prop.

Hope this clears up information about our Missile and Rocket conversions.

-Seth

Seth- I'd definitely like to discuss this further offline. Please PM me when you have a minute. What happened to the 1,700 RPM springs / pins that prevent feathering?

Regardless of of what the experts say, I'd like to run the experiment & try to feather the prop with power. HS any Rocket owner tried this?

KevinR · October 28, 2015

Just finished an informative conversation with a man who has been overhauling propellers for 35 years. Here's a quick recap:

(for the lawyers out there, the following is my interpretation of the conversation- your mileage may vary... don't try this at home...)

if the prop governor fails, the prop will go into feather if the governor is working properly
there are only three prop governor failure modes he has ever seen in his career:
1. complete loss of engine oil pressure which means your engine is about to quit anyway
2. some internal failure in the engine which injects more metal into the engine than can be held by the oil filter, which then clogs up the governor with metal, which means your engine is about to quit anyway
3. the shaft that transmits power from the engine to the governor shears. Only witnessed one time in 35 years.
since the same oil, approx one cup, stays in the governor until the prop is feathered, it is recommended that we cycle the prop into full feather at least once a year. Paraffin can build up in the oil which could prevent the prop from going into feather- that would be bad in the case of an engine failure. When we feather the prop, all of the oil is drained from the governor back into the engine oil sump. Feathering the prop cycles new oil into the governor. Maybe we should make feathering the prop part of our pre oil change routine- purge the old governor oil into the sump right before you drain the oil.
lock pins in the hub engage below around 600-800RPM. This is why our props don't go into feather at shutdown. Centrifugal force retracts the locks.
***see above: you must feather the prop before the locks engage if the engine fails and you want to feather the prop.
full explanation with pictures here: http://www.mccauley.textron.com/tech_guide.pdf

I haven't flown a multi-engine airplane with a propeller in several years. Jets are much easier to manage when one engine stops working. This thread reminded me that my Rocket isn't a normal single engine airplane- it's a twin without the second engine. Every Rocket owner would benefit from an hour or two of multi-engine training just to get familiar with the operation of a fully-feathering prop.

After I get a dozen hours post-overhaul, I will orbit the airport at 10,000 feet and feather the prop using this procedure (open to suggestions if I'm missing something):

refresh engine out / glider procedures. Decide on a restart min altitude. If the engine is not operating below that altitude, commit to landing power off. i.e. fly the airplane.
coordinate with tower. select a time with minimum traffic. home field is fairly low operation volume, 80' MSL and 7,500' runway.
climb to 10,000
slowly reduce power to 20" MP being careful to not exceed max cooldown rate
establish a orbit pattern directly over the airport
notify tower of start of test
record IAS
reduce prop to 1700 RPM, then quickly pull to feather
mixture cutoff
start the timer
maintain altitude until IAS = best glide speed for current weight
record the time at top of descent
record vertical speed when stable at best glide speed
record time, IAS, and VSI at 9,000' and every 500 feet until reaching 6,000'
at 6,000' begin restart
1. prop full forward
2. mixture rich
3. if prop does not begin turning, engage starter
4. if engine not restarted by 5,000', begin ENGINE FAILURE emergency procedure
5. if engine not restarted by 4,000', commit to engine out landing. FLY THE AIRPLANE
6. enter high key @ 3,000', low key @ 1,500', gear, flaps on final when landing is certain.
7. try to be like Bob Hoover and roll to parking spot with the engine off.

Seth · October 28, 2015

Just finished an informative conversation with a man who has been overhauling propellers for 35 years. Here's a quick recap:

(for the lawyers out there, the following is my interpretation of the conversation- your mileage may vary... don't try this at home...)

if the prop governor fails, the prop will go into feather if the governor is working properly

there are only three prop governor failure modes he has ever seen in his career:

complete loss of engine oil pressure which means your engine is about to quit anyway

some internal failure in the engine which injects more metal into the engine than can be held by the oil filter, which then clogs up the governor with metal, which means your engine is about to quit anyway

the shaft that transmits power from the engine to the governor shears. Only witnessed one time in 35 years.

since the same oil, approx one cup, stays in the governor until the prop is feathered, it is recommended that we cycle the prop into full feather at least once a year. Paraffin can build up in the oil which could prevent the prop from going into feather- that would be bad in the case of an engine failure. When we feather the prop, all of the oil is drained from the governor back into the engine oil sump. Feathering the prop cycles new oil into the governor. Maybe we should make feathering the prop part of our pre oil change routine- purge the old governor oil into the sump right before you drain the oil.

lock pins in the hub engage below around 600-800RPM. This is why our props don't go into feather at shutdown. Centrifugal force retracts the locks.

***see above: you must feather the prop before the locks engage if the engine fails and you want to feather the prop.

full explanation with pictures here: http://www.mccauley.textron.com/tech_guide.pdf

I haven't flown a multi-engine airplane with a propeller in several years. Jets are much easier to manage when one engine stops working. This thread reminded me that my Rocket isn't a normal single engine airplane- it's a twin without the second engine. Every Rocket owner would benefit from an hour or two of multi-engine training just to get familiar with the operation of a fully-feathering prop.

After I get a dozen hours post-overhaul, I will orbit the airport at 10,000 feet and feather the prop using this procedure (open to suggestions if I'm missing something):

refresh engine out / glider procedures. Decide on a restart min altitude. If the engine is not operating below that altitude, commit to landing power off. i.e. fly the airplane.

coordinate with tower. select a time with minimum traffic. home field is fairly low operation volume, 80' MSL and 7,500' runway.

climb to 10,000

slowly reduce power to 20" MP being careful to not exceed max cooldown rate

establish a orbit pattern directly over the airport

notify tower of start of test

record IAS

reduce prop to 1700 RPM, then quickly pull to feather

mixture cutoff

start the timer

maintain altitude until IAS = best glide speed for current weight

record the time at top of descent

record vertical speed when stable at best glide speed

record time, IAS, and VSI at 9,000' and every 500 feet until reaching 6,000'

at 6,000' begin restart

prop full forward

mixture rich

if prop does not begin turning, engage starter

if engine not restarted by 5,000', begin ENGINE FAILURE emergency procedure

if engine not restarted by 4,000', commit to engine out landing. FLY THE AIRPLANE

enter high key @ 3,000', low key @ 1,500', gear, flaps on final when landing is certain.

try to be like Bob Hoover and roll to parking spot with the engine off.

I like 15 - 7. Try to be like Bob Hoover and roll to parking spot with the engine off.

The problem is from a risk perspective. Even at 10,000 feet, I'm not sure if personally would want to actually feather the prop on a single engine. Though it'll just be heavy glider, if I were to bend the airframe, it's still a risk that I decided upon.

I'm not sure how a ground run would work. I don't even know if it's possible. For those who have, what occurs if you feather a prop on the ground?

For oil changes, does it make sense to feather it on the ground, change the oil, and then startup? What harm will occur to the engine with the locking pins that pop out at 600-800 RPM?

This is a VERY useful thread for the Rocket and Missile owners.

-Seth

M016576 · October 28, 2015

I like 15 - 7. Try to be like Bob Hoover and roll to parking spot with the engine off.

The problem is from a risk perspective. Even at 10,000 feet, I'm not sure if personally would want to actually feather the prop on a single engine. Though it'll just be heavy glider, if I were to bend the airframe, it's still a risk that I decided upon.

I'm not sure how a ground run would work. I don't even know if it's possible. For those who have, what occurs if you feather a prop on the ground?

For oil changes, does it make sense to feather it on the ground, change the oil, and then startup? What harm will occur to the engine with the locking pins that pop out at 600-800 RPM?

This is a VERY useful thread for the Rocket and Missile owners.

-Seth

prior to taking the runway, during your run up checks, don't you pull the condition lever all the way out to cycle the oil? That's feathering the prop, right? (I.e.- locking pins are retracted and condition lever comes all the way out).... Or is that an old habit pattern I have from another airplane?

M20F · October 28, 2015

prior to taking the runway, during your run up checks, don't you pull the condition lever all the way out to cycle the oil? That's feathering the prop, right? (I.e.- locking pins are retracted and condition lever comes all the way out).... Or is that an old habit pattern I have from another airplane?

The prop won't feather above the RPM threshold which is usually around 700RPM. So when you cycle you just go through pitch change and circulate the oil out of the governor (and make sure it is working). Feathering the prop puts the blades flat so that their is no drag from windmilling and minimal drag from the prop itself. Useful in a twin, not so much in a single.

RocketAviator · October 28, 2015

I like 15 - 7. Try to be like Bob Hoover and roll to parking spot with the engine off.

The problem is from a risk perspective. Even at 10,000 feet, I'm not sure if personally would want to actually feather the prop on a single engine. Though it'll just be heavy glider, if I were to bend the airframe, it's still a risk that I decided upon.

I'm not sure how a ground run would work. I don't even know if it's possible. For those who have, what occurs if you feather a prop on the ground?

For oil changes, does it make sense to feather it on the ground, change the oil, and then startup? What harm will occur to the engine with the locking pins that pop out at 600-800 RPM?

This is a VERY useful thread for the Rocket and Missile owners.

-Seth

i have featheredmy prop on the ground when shutting down once. No issues at all. When restart prop returned to normal... 150 hrs since no problem.

RocketAviator · October 28, 2015

Looked odd with prop flat... like a twin but NOT!

Houman · October 28, 2015

Looked odd with prop flat... like a twin but NOT!

I have always wondered about that, never done it my self tough !!!

**Yooper Rocketman** · October 29, 2015

I have feathered my prop on the ground. I didn't know that (keeping the RPM's up a bit) for feathering was important until I had an incident later.

A group of us local pilots had spent about 3 days looking for an old friend that went down while flying wolf patrol for the DNR. Later we found he had a heart attack, in his 80's, and died doing what he loved. The old Cessna 182 flew until it ran out of gas, in circles, and gently went into the trees. Not even sure if the plane got damaged much. Anyway, during lunch on one of those search days, I inquired about the "full feathering prop", as at the time I was a fairly new Rocket owner. A couple of commercial pilots and an IA I work with told me I could exercise it on the ground during my run up, but drop the RPM's down to about 1200 or so. I did, it worked.

A few days later I am doing a flight to a small, quiet airport about 30 minutes east of my home base, and center is keeping me up at 7000' due to traffic with an IFR clearance coming out of the same airport. I pulled power, progressively, expecting a slam dunk once he got off. By the time I got my descent clearance, I was high enough I thought why not try an emergency landing procedure. I pulled power to idle and pointed the nose down at best glide speed. Well, with the 3 blade prop, by the time I got down to 1,000' above the runway, it was apparent I wasn't going to make it. But hey, I was just told how great feathering the prop is, so.......I feathered it. Little did I realize a fully feathered prop at idle RPM is WAY TOO much drag on the engine, and about the time I realized it was going to kill it and put my hand on the prop knob, she quit.

After the "oh sh.t" moment (or two or three), I decided the most ingrained advice my flight instructor gave me would keep me a alive; fly the airplane. I looked down and I was about 500' above the airport, with a stopped fuel injected engine (never been easy to start hot) and a prop in full feather, If I screw around trying to get the prop out of feather and the engine running, I may full well crash this thing from inattention to the important thing, fly the airplane. I would clearly make the run out area, and the insurance company can replace the plane. My descent rate dropped from 500 FPM to 300 FPM. It was surreal, only hearing the wind noise (and no engine). As I further assessed the situation, it began to appear I would actually make the runway..........and I did, by about 1,000'.

I sat on the runway digesting what I had just did for about a minute or two. Then I realized I was picking up a customer to bring back to the dealership to close on an new log truck and drive the it home. I pushed the prop forward, cranked the engine, it came out of feather, started, and I taxied to the terminal (luckily where I was stopped on the runway was not visible from the building. Needless to say, the customer heard none of the details about my approach and landing, my biggest hope being there was no lingering smell from my shorts. It was a few days before I discussed this with anyone.

I will never do that again, but have full confidence on the glide ratio on a Rocket. It's pretty impressive. If I DO lose the engine, I will not hesitate to feather.

Tom

**aviatoreb** · October 29, 2015

I have feathered my prop on the ground. I didn't know that (keeping the RPM's up a bit) for feathering was important until I had an incident later.

A group of us local pilots had spent about 3 days looking for an old friend that went down while flying wolf patrol for the DNR. Later we found he had a heart attack, in his 80's, and died doing what he loved. The old Cessna 182 flew until it ran out of gas, in circles, and gently went into the trees. Not even sure if the plane got damaged much. Anyway, during lunch on one of those search days, I inquired about the "full feathering prop", as at the time I was a fairly new Rocket owner. A couple of commercial pilots and an IA I work with told me I could exercise it on the ground during my run up, but drop the RPM's down to about 1200 or so. I did, it worked.

A few days later I am doing a flight to a small, quiet airport about 30 minutes east of my home base, and center is keeping me up at 7000' due to traffic with an IFR clearance coming out of the same airport. I pulled power, progressively, expecting a slam dunk once he got off. By the time I got my descent clearance, I was high enough I thought why not try an emergency landing procedure. I pulled power to idle and pointed the nose down at best glide speed. Well, with the 3 blade prop, by the time I got down to 1,000' above the runway, it was apparent I wasn't going to make it. But hey, I was just told how great feathering the prop is, so.......I feathered it. Little did I realize a fully feathered prop at idle RPM is WAY TOO much drag on the engine, and about the time I realized it was going to kill it and put my hand on the prop knob, she quit.

After the "oh sh.t" moment (or two or three), I decided the most ingrained advice my flight instructor gave me would keep me a alive; fly the airplane. I looked down and I was about 500' above the airport, with a stopped fuel injected engine (never been easy to start hot) and a prop in full feather, If I screw around trying to get the prop out of feather and the engine running, I may full well crash this thing from inattention to the important thing, fly the airplane. I would clearly make the run out area, and the insurance company can replace the plane. My descent rate dropped from 500 FPM to 300 FPM. It was surreal, only hearing the wind noise (and no engine). As I further assessed the situation, it began to appear I would actually make the runway..........and I did, by about 1,000'.

I sat on the runway digesting what I had just did for about a minute or two. Then I realized I was picking up a customer to bring back to the dealership to close on an new log truck and drive the it home. I pushed the prop forward, cranked the engine, it came out of feather, started, and I taxied to the terminal (luckily where I was stopped on the runway was not visible from the building. Needless to say, the customer heard none of the details about my approach and landing, my biggest hope being there was no lingering smell from my shorts. It was a few days before I discussed this with anyone.

I will never do that again, but have full confidence on the glide ratio on a Rocket. It's pretty impressive. If I DO lose the engine, I will not hesitate to feather.

Tom

That was a surprise Tom.

As I said - I did the same, but by luck it was a much more benign scenario since I too was practicing engine outs and decided what the heck let me see what the full feather really does.....but I was already lined up on a long final for the runway. And so full feather at idle the engine quite, but my hand was still on the blue knob - so I did just like I heard to do if your engine ever quits right after you did something - undo it. So just at the moment it stopped - I relocated the blue knob to where it was before it quite - and it fired right up again due to windmilling. It was only shut down for a moment. Barely even - just enough that after the flight I was thinking - wow - that really happen?

Wow yes what a glide it has - it felt like it jumped up into the air.

M016576 · October 29, 2015

The prop won't feather above the RPM threshold which is usually around 700RPM. So when you cycle you just go through pitch change and circulate the oil out of the governor (and make sure it is working). Feathering the prop puts the blades flat so that their is no drag from windmilling and minimal drag from the prop itself. Useful in a twin, not so much in a single.

the way I'm reading the posts sbove, it seems like you must have more than 700 or so rpm to fully feather the prop.., thus pulling the condition lever back all the way while at 1600rpm would feather, right? Or do I have it backwards?

**jetdriven** · October 29, 2015

Just finished an informative conversation with a man who has been overhauling propellers for 35 years. Here's a quick recap:

(for the lawyers out there, the following is my interpretation of the conversation- your mileage may vary... don't try this at home...)

if the prop governor fails, the prop will go into feather if the governor is working properly

there are only three prop governor failure modes he has ever seen in his career:

complete loss of engine oil pressure which means your engine is about to quit anyway

some internal failure in the engine which injects more metal into the engine than can be held by the oil filter, which then clogs up the governor with metal, which means your engine is about to quit anyway

the shaft that transmits power from the engine to the governor shears. Only witnessed one time in 35 years.

since the same oil, approx one cup, stays in the governor until the prop is feathered, it is recommended that we cycle the prop into full feather at least once a year. Paraffin can build up in the oil which could prevent the prop from going into feather- that would be bad in the case of an engine failure. When we feather the prop, all of the oil is drained from the governor back into the engine oil sump. Feathering the prop cycles new oil into the governor. Maybe we should make feathering the prop part of our pre oil change routine- purge the old governor oil into the sump right before you drain the oil.

lock pins in the hub engage below around 600-800RPM. This is why our props don't go into feather at shutdown. Centrifugal force retracts the locks.

***see above: you must feather the prop before the locks engage if the engine fails and you want to feather the prop.

full explanation with pictures here: http://www.mccauley.textron.com/tech_guide.pdf

I haven't flown a multi-engine airplane with a propeller in several years. Jets are much easier to manage when one engine stops working. This thread reminded me that my Rocket isn't a normal single engine airplane- it's a twin without the second engine. Every Rocket owner would benefit from an hour or two of multi-engine training just to get familiar with the operation of a fully-feathering prop.

After I get a dozen hours post-overhaul, I will orbit the airport at 10,000 feet and feather the prop using this procedure (open to suggestions if I'm missing something):

refresh engine out / glider procedures. Decide on a restart min altitude. If the engine is not operating below that altitude, commit to landing power off. i.e. fly the airplane.

coordinate with tower. select a time with minimum traffic. home field is fairly low operation volume, 80' MSL and 7,500' runway.

climb to 10,000

slowly reduce power to 20" MP being careful to not exceed max cooldown rate

establish a orbit pattern directly over the airport

notify tower of start of test

record IAS

reduce prop to 1700 RPM, then quickly pull to feather

mixture cutoff

start the timer

maintain altitude until IAS = best glide speed for current weight

record the time at top of descent

record vertical speed when stable at best glide speed

record time, IAS, and VSI at 9,000' and every 500 feet until reaching 6,000'

at 6,000' begin restart

prop full forward

mixture rich

if prop does not begin turning, engage starter

if engine not restarted by 5,000', begin ENGINE FAILURE emergency procedure

if engine not restarted by 4,000', commit to engine out landing. FLY THE AIRPLANE

enter high key @ 3,000', low key @ 1,500', gear, flaps on final when landing is certain.

try to be like Bob Hoover and roll to parking spot with the engine off.

prop governor failure is rare. We are discussing soemthing that sonds and feels good but I cant find any evidence of this scenario happening.

It would be worthwhile to feather check the engine once a year but there is no way oil remains in the governor for a year. The oil is pressurized to ~600 PSI and it is always moving forward. the transfer bearing and the prop leak enough oil to refresh it every couple minutes.

I'd do it over an airport but I wouldnt initiate the emergency procedure at 5000, thats early...Just push the prop lever full forward, bump the starter if it wont unfeather, then give it the mixture. It will light off. Just let it warm up at 18" for a couple minutes before giving it hell.

M20F · October 29, 2015

the way I'm reading the posts sbove, it seems like you must have more than 700 or so rpm to fully feather the prop.., thus pulling the condition lever back all the way while at 1600rpm would feather, right? Or do I have it backwards?

On a twin engine set up (the missile and rocket use an engine from a twin) the propeller is constantly trying to go into feather through counterweights (Hartzell) or springs (Mcauley). The oil from the govenor pushes against these two things to keep the engine out of feather. When you lose all oil pressure the engine goes to feather. This is a safety feature as on a twin if one engine goes you have another to carry you along and a windmilling prop is about -150 FPM of drag.

When you turn the engine off obviously you lose oil pressure and having the prop fly into feather every shutdown isn't desireable. To counteract that, there are pins that when the prop is spinning above @700 rpm are pushed out by centrifugal force. Pull the prop to feather above 700 rpm and the oil runs out of it and it goes to feather. Below 700rpm there is not enough centrifugal force to hold the pins out so they slide in and prevent the counterweights/spring from putting the prop all the way to feather.

M20F · October 29, 2015

Just push the prop lever full forward, bump the starter if it wont unfeather, then give it the mixture. It will light off. Just let it warm up at 18" for a couple minutes before giving it hell.

If it is feathered it won't be windmilling and you will need to engage the starter and hope it has enough oomph to spin the prop around in the air. One shouldn't assume that just because the starter has the juice to pop it out of feather on the ground that it is going to have the same juice to do it in the air where there is a lot of drag on that prop to where the starter may not be able to overcome and spin it fast enough to start. Personally I would be a bit leery of feathering a single in the air for any reason the same way I am a bit leery of turning the engine off to practice engine outs.

**carusoam** · October 29, 2015

This thread shows the value of thinking things all the way through before acting on a good idea. I am glad you guys are openly sharing your experiences.

I am surprised the experienced prop guy hasn't seen the loss of the internal crank seal. A real loss of oil pressure from the govenor that doesn't produce an engine catastrophe. I learned about this problem by an EAA friend who was familiar with it. This was a few days before the word 'Google' was invented....

The seal is just a sheet metal aluminum plug on the crank, opposite the prop. See if your crank has this plug. Maybe it isn't bored completely through.

Pushing the prop all the way in to 2700 rpm adds enough braking you can feel it. Pulling the prop back, it feels like an acceleration. Going to full feather would require an adjustment in attitude to maintain best glide speed.

Best regards,

-a-

Edited October 29, 2015 by carusoam

Seth · October 29, 2015

The prop won't feather above the RPM threshold which is usually around 700RPM. So when you cycle you just go through pitch change and circulate the oil out of the governor (and make sure it is working). Feathering the prop puts the blades flat so that their is no drag from windmilling and minimal drag from the prop itself. Useful in a twin, not so much in a single.

Well, it does get you better glide when your engine quits in a single!

-Seth

Seth · October 29, 2015

i have featheredmy prop on the ground when shutting down once. No issues at all. When restart prop returned to normal... 150 hrs since no problem.

Was that by mistake or on purpose? This may be the new standard operating procedure just before oil changes.

-Seth

M20F · October 29, 2015

Well, it does get you better glide when your engine quits in a single!

-Seth

It can depending on the prop. In my M20F I have a scimitar prop and shoving in full pitch on descent has a drag impact of about zero so feathering it , probably wouldn't add anything appreciable to the equation. In a 320 I fly shoving in full prop is akin to throwing out two anchors on final. Personally I am not a fan of full feathering props on singles for all the reasons discussed, there are a lot more down sides than upsides to it and while you might squeak a bit more glide out in an emergency it probably wouldn't be enough to make a difference. I take nothing away from a Missile or a Rocket, great planes. Just like I see cabin size as a negative in my F versus say a Bonanza, I don't see the full feathering as an upside when looking objectively. My opinion only and I would look at cranking up the pins (assuming that is possible) so that it wasn't featherable.

I would add that where you need to be careful isn't the failure of the governor but oil pressure loss. As I talked about in a previous post on this thread we had a T-Bone based with us that had intermittent oil pressure issues which would cause the engine to fly into feather at all differing conditions of flight (it got fixed fairly quickly but because it was intermittent it took 2-3 occurrences to identify what the heck was going on) . This is going to be far more likely an situation than something breaking. Once the pressure can't keep the weights/springs held back it will feather and without that pressure you are never going to get it to start up again as it won't transition back out of feather. It can be a real nightmare trying to restart a twin where you have one good engine holding you up, odds of getting a single restarted are a little too unlikely for me to ever want to play around with that for real.

Good discussion though!

Seth · October 29, 2015

It can depending on the prop. In my M20F I have a scimitar prop and shoving in full pitch on descent has a drag impact of about zero so feathering it , probably wouldn't add anything appreciable to the equation. In a 320 I fly shoving in full prop is akin to throwing out two anchors on final. Personally I am not a fan of full feathering props on singles for all the reasons discussed, there are a lot more down sides than upsides to it and while you might squeak a bit more glide out in an emergency it probably wouldn't be enough to make a difference. I take nothing away from a Missile or a Rocket, great planes. Just like I see cabin size as a negative in my F versus say a Bonanza, I don't see the full feathering as an upside when looking objectively. My opinion only and I would look at cranking up the pins (assuming that is possible) so that it wasn't featherable.

I would add that where you need to be careful isn't the failure of the governor but oil pressure loss. As I talked about in a previous post on this thread we had a T-Bone based with us that had intermittent oil pressure issues which would cause the engine to fly into feather at all differing conditions of flight (it got fixed fairly quickly but because it was intermittent it took 2-3 occurrences to identify what the heck was going on) . This is going to be far more likely an situation than something breaking. Once the pressure can't keep the weights/springs held back it will feather and without that pressure you are never going to get it to start up again as it won't transition back out of feather. It can be a real nightmare trying to restart a twin where you have one good engine holding you up, odds of getting a single restarted are a little too unlikely for me to ever want to play around with that for real.

Good discussion though!

Good points.

-Seth

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