feathering prop on wrong engine

olasek

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olasek
There is a discussion on another forum that relates to the recent crash of Navajo in Poland. Something like 10 skydivers + pilot perished. It is already known that one of the engines failed - possibly a wrong fuel was used. A quick question - if a pilot were to feather a wrong engine (the one that did not fail) what would it do?. Is it even possible to have an engine running at full power with a feathered prop? Any significant asymmetry in such scenario?
 
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Turn into a glider, but it wouldn't happen, you would realize what was going on before you got to an irreversible point. In fact, I'm not sure if the prop will fully feather if there is full power on it. I do know that on a run up I pull back into the feather detent before going forward again and I have never stalled the engine doing so. It's very obvious when you pull back on a prop that is the only one with power.

If he got loaded with JetA and switched tanks on both sides, he likely lost both engines, they don't last long when that happens.
 
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If he got loaded with JetA and switched tanks on both sides, he likely lost both engines, they don't last long when that happens.

I've seen the results of that in a pair of TIGO 541's. Not pretty. Airplane was totaled. Got to inspect the engine parts. What a mess; pistons beaten to death, connecting rods bent, ad infinitum.
 
Yeah, it's not pretty at all, about as extreme of detonation damage as it gets.
 
I don't think it was the case of using a Jet-A, they allegedly used some mogas from unauthorized (non-aviation related) source (they apparently had their own shady fuel container at the airport). For days before the failure people around noticed that this Navajo's exhaust was very 'smoky', not pretty, some even took photographs. A preliminary report (in Polish) was already published and though very sketchy it does mentioned potentially unauthorized fuel used. They also uncovered other multiple 'violations'. What emerges is a picture of the owner who tried to save on aircraft operating expenses while heavily using this aircraft for parachuting (some say the aircraft could do 10 trips a day).
 
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Turn into a glider, but it wouldn't happen, you would realize what was going on before you got to an irreversible point.
The record says otherwise, at least for piston engines. The wrong prop lever has been retarded before, and it has resulted in failure of the "good" engine resulting in an accident. It's largely a matter of training, and how fast the pilot chooses to execute the drill. When someone gets in the mode of "I gotta do it right now as fast as I can", bad things happen, and this is one possibility. Note that you don't have to get the prop lever all the way to the feather position before the RPM on an engine with the throttle full forward (which is where it should be if you're executing the engine failure drill in the correct order) gets so low it reaches the point of detonation, and that can kill the engine before the prop feathers -- even halfway back may be enough.

Whether that's what happened in the instant case is nothing but speculation at this point, and if it's a turbine engine, then it's a whole 'nother ball game. But the point I'm making is that while you want to get the engine failure drill completed in a timely manner, the extra two seconds it takes to verify that the prop lever you're retarding is the one on the "bad" engine isn't going to makes the difference between life and death. So during engine failure drills, take enough time to make sure you're doing the right thing at each step, and if the Law of Exercise works, you'll do the same in a real engine failure situation, and that could save your life.

In fact, I'm not sure if the prop will fully feather if there is full power on it.
On regular piston twins, it will, but not before serious damage is done to the engine.

I do know that on a run up I pull back into the feather detent before going forward again and I have never stalled the engine doing so.
You're typically at a very low power setting (maybe 50% or so) during the run-up feather check on a piston twin. Being at full throttle would be another story entirely.

All that said, if the issue was incorrect and unacceptable fuel, then the other engine was going to die soon enough after the first one anyway, and it really wouldn't matter what the pilot did (right or wrong) with the engine controls on the second engine.
 
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I don't think it was the case of using a Jet-A, they allegedly used some mogas from unauthorized (non-aviation related) source (they apparently had their own shady fuel container at the airport). For days before the failure people around noticed that this Navajo's exhaust was very 'smoky', not pretty, some even took photographs. A preliminary report (in Polish) was already published and though very sketchy it does mentioned potentially unauthorized fuel used. They also uncovered other multiple 'violations'. What emerges is a picture of the owner who tried to save on aircraft operating expenses while heavily using this aircraft for parachuting (some say the aircraft could do 10 trips a day).

dead victim count seems high for the number of seats a Navajo has. Wonder if weight was also a problem
 
There were 11 victims + 1 survivor.
It was a pressurized Navajo, outfitted for jumping, if you look at useful load of a PA-31P it is not out of realm of possibility to carry that many people.

The aircraft was on FAA "N" registry.

By the way someone just days before the accident took a photograph of this aircraft with smoking engines:

http://lotnictwo.net.pl/gallery/pho...ate/reg-N11WB/cn-31P-7630005/foto-254730.html
 
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There were 11 victims + 1 survivor.
It was a pressurized Navajo, outfitted for jumping, if you look at useful load of a PA-31P it is not out of realm of possibility to carry that many people.

You mean like that one in the Bahamas with nine passengers in a C-402B? Overloading even a little spoils engine-out performance in a piston twin faster than anyone can stand it.

I cringe at the thought of that much weight in a piston twin, on one engine. No matter what the book data says, brand-new airplane, with factory test pilot, with fresh engines.

Me wonders if an older bird, with a not-factory test pilot, could even be made to climb, with that kind of load.

And we are not even talking CG-shift, etc issues, unbelted passengers, etc.
 
By the way someone just days before the accident took a photograph of this aircraft with smoking engines:

http://lotnictwo.net.pl/gallery/pho...ate/reg-N11WB/cn-31P-7630005/foto-254730.html

That looks like tire smoke on landing to me, maybe touching down with the brakes on?

Having flown a P-Navajo for a year, I can't imagine using such a thing for jumpers. I've flown a Chieftain set up in commuter seating that would seat eleven, but the P-Navajo was shorter. It had club seats (4), a sideways facing seat and a removable seat for the baggage area plus the crew for a total of eight. On one engine, the other one just makes a lot of noise until the crash (+190 ft/min @ SL density, IIRC, but don't count on it any other time). In other words, you don't need to shut down the wrong engine to have a bad day even with avgas, especially if you're overloaded. Those are geared engines, man. Dropping and chopping in that all day? :yikes:

dtuuri
 
dead victim count seems high for the number of seats a Navajo has. Wonder if weight was also a problem

Not for a stripped out Chieftain, heck, even a stripped out 325 would likely still be ok, leave a bunch of fuel on the ground and a 310hp would work. Jump panes get pretty lightened up as far as interiors, and don't have to carry a bunch of fuel. Not saying for sure they were ok on weight, but I don't see where it's impossible to put 11 onboard and be ok.
 
There were 11 victims + 1 survivor.
It was a pressurized Navajo, outfitted for jumping, if you look at useful load of a PA-31P it is not out of realm of possibility to carry that many people.

The aircraft was on FAA "N" registry.

By the way someone just days before the accident took a photograph of this aircraft with smoking engines:

http://lotnictwo.net.pl/gallery/pho...ate/reg-N11WB/cn-31P-7630005/foto-254730.html

A P-Nav? WTF? That makes no sense to use as a jump plane. He must have got it for free.
 
Not for a stripped out Chieftain, heck, even a stripped out 325 would likely still be ok, leave a bunch of fuel on the ground and a 310hp would work. Jump panes get pretty lightened up as far as interiors, and don't have to carry a bunch of fuel. Not saying for sure they were ok on weight, but I don't see where it's impossible to put 11 onboard and be ok.

was a P-Navajo

http://aviation-safety.net/wikibase/wiki.php?id=167788

N11WB: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=11WB

http://www.planespotters.net/Aviation_Photos/photo.show?id=468579&size=l

AVCANADA Forums http://www.avcanada.ca/forums2/viewtopic.php?f=118&t=97551
 
That looks like tire smoke on landing to me, maybe touching down with the brakes on?

Having flown a P-Navajo for a year, I can't imagine using such a thing for jumpers. I've flown a Chieftain set up in commuter seating that would seat eleven, but the P-Navajo was shorter. It had club seats (4), a sideways facing seat and a removable seat for the baggage area plus the crew for a total of eight. On one engine, the other one just makes a lot of noise until the crash (+190 ft/min @ SL density, IIRC, but don't count on it any other time). In other words, you don't need to shut down the wrong engine to have a bad day even with avgas, especially if you're overloaded. Those are geared engines, man. Dropping and chopping in that all day? :yikes:

dtuuri


Skydivers are not required to be in seats (typically they just sit on the floor). Seatbelts are either non-existant, or they just somehow secure their parachute straps to the wall. You can fit a lot of folks in a plane with each one sitting between the person behind them's legs. That, and it's not a problem for the flight to operate with minimum fuel.
 
Skydivers are not required to be in seats (typically they just sit on the floor). Seatbelts are either non-existant, or they just somehow secure their parachute straps to the wall. You can fit a lot of folks in a plane with each one sitting between the person behind them's legs. That, and it's not a problem for the flight to operate with minimum fuel.

I plead ignorance of anything to do with jump operations. Maybe they were just looking at the horsepower? The thing has 425 HP/side. Let's see, if you remove the bar and ice bucket, all the leather seats, one alternator, air conditioner, locker tank, pressure pump for the flight instruments, the heavy airstair door and the pressurization controller and then only put in enough avgas for an hour's flight (about 50 gallons)... maybe it would be real profitable? :dunno:

Still won't climb on one engine...

dtuuri
 
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The record says otherwise, at least for piston engines. The wrong prop lever has been retarded before, and it has resulted in failure of the "good" engine resulting in an accident. .

Yep, I found this to be a short coming of doing the 'verify' stage of identify, verify, and feather process with the throttle. It introduces the chance to grab the wrong handle after verifying. If you use the prop to verify, you are consciously listening for a reduction in noise to tell you you have the working engine, if that
Doesn't happen by the time you hit the detent, continue in and feather. It also cuts a couple of seconds off the process when it counts on take off.
 
How does a sky dive plane NOT have an emergency field in gliding distance? Honestly, in a loaded piston twin I'd not even think about the SE performance. Extend the glide is a bonus...
 
Yep, I found this to be a short coming of doing the 'verify' stage of identify, verify, and feather process with the throttle. It introduces the chance to grab the wrong handle after verifying. If you use the prop to verify, you are consciously listening for a reduction in noise to tell you you have the working engine, if that
I've been an ME instructor a long time, and I've never heard of anyone recommending using the prop lever to verify. First, pulling back the prop lever is going to get a big noise change on a bad engine just as on a good engine if the bad engine is still spinning up to speed (and they often are). Second, I see too much chance of destroying the good engine by being too quick to continue back to the feather position if you have grabbed the prop lever on the good engine.

Doesn't happen by the time you hit the detent, continue in and feather.
With the throttles full forward anywhere near cruising speed, you can destroy the good engine before you get to the feather detent.
It also cuts a couple of seconds off the process when it counts on take off.
If you think two seconds is the difference in a Part 23 light twin, you need to be skipping all that stuff and just go "Throttles - retard, land straight ahead". They just aren't designed to give you that level of protection, and the penalty for getting it wrong is death.
 
I've been an ME instructor a long time, and I've never heard of anyone recommending using the prop lever to verify.
So what's the proper technique to verify - with the rudder? - "dead foot dead engine"?
 
I've been an ME instructor a long time, and I've never heard of anyone recommending using the prop lever to verify. First, pulling back the prop lever is going to get a big noise change on a bad engine just as on a good engine if the bad engine is still spinning up to speed (and they often are). Second, I see too much chance of destroying the good engine by being too quick to continue back to the feather position if you have grabbed the prop lever on the good engine.

With the throttles full forward anywhere near cruising speed, you can destroy the good engine before you get to the feather detent.
If you think two seconds is the difference in a Part 23 light twin, you need to be skipping all that stuff and just go "Throttles - retard, land straight ahead". They just aren't designed to give you that level of protection, and the penalty for getting it wrong is death.

Ask Bruce.;) along with the hand foot coordination drill.
 
So what's the proper technique to verify - with the rudder? - "dead foot dead engine"?
Rudder ("dead foot - dead engine") is "Identify" -- the leg that isn't doing anything ("dead leg") is the dead engine. Throttle is the "Verify" -- you pull it back and nothing changes, "you've got the right one, baby." If you pull it back and the airplane yaws back the other way, you've pulled the good one.
 
Ask Bruce.;) along with the hand foot coordination drill.
Better yet -- when you take your CFI-ME ride, ask the examiner administering the ride. Or just read the FAA's Airplane Flying Handbook:
The “verify” step directs the pilot
to retard the throttle of the engine thought to have​
failed. No change in performance when the suspected
throttle is retarded is verification that the​
correct engine has been identified as failed.​
AFH, page 12-20.

For the reasons discussed above, retarding the prop lever on a piston twin can be an irrevocable mistake, but retarding the throttle is almost never an irrevocable mistake, especially since you'll recognize you've pulled the wrong one after only an inch or two of travel -- and that's not equally true of the prop control. Hence, for piston twins, identify with rudder/leg, verify with throttle, and only then feather with prop.
 
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Rudder ("dead foot - dead engine") is "Identify" -- the leg that isn't doing anything ("dead leg") is the dead engine. Throttle is the "Verify" -- you pull it back and nothing changes, "you've got the right one, baby." If you pull it back and the airplane yaws back the other way, you've pulled the good one.
"Identify" better agrees with "Verify" :wink2:
I reckon one must be pretty quick in all this detective work ...
 
My MEI also taught to put the heading bug on runway heading. After a failure on takeoff, the bug points to the working engine.

Turbulence can sometimes make it take a bit to figure out what the "ball" is doing.
 
The one time I went skydiving we were in a Skylane. I don't know how many people were in it, but the number was way north of 4.
 
I reckon one must be pretty quick in all this detective work ...
Well, maybe, but don't rush it. Old story about an overly hasty BOAC crew...

Hot (at least by British standards) summer afternoon in London, England. A BOAC 707 (which dates the story two ways) is departing Heathrow for New York (JFK? maybe still Idlewild then? :dunno:). Summer means lots of folks visiting England, so the flight is chock full, and with range of a 707 and the winds on a westbound transatlantic flight, the fuel tanks are equally full. Right after takeoff, they get a fire light on the #1 engine. The crew leaps into action, and performs what is, according to the CVR, the fastest engine shutdown drill ever seen in training or operational experience...


...on the #2 engine.


Oops.

Problem now is that once you pull the E-handle on a 707, the fuel shutoff valves in the pylon are irrevocably closed -- only way to re-open them is to go out there with a wrench, and unlike the old China Clippers PanAm used to fly, that's not an option on a 707, so #2 is on the bench for the rest of the match. Further, fully loaded, with two engines out on the same side, the 707's Vmc is faster than you can go and still have any climb capability, so now they can't shut down #1 and still make it back to the runway.

As they say over there, "Bugger."

The crew bites the bullet, keeps #1 running, hollers for help, and bends the plane back around to the runway visually. They land it OK, and finally pull the #1 E-handle (as well as #3 and #4 as part of the emergency evacuation drill), but by then the fire has spread above the #1 pylon to the wing, so there was no stopping that show. They did get everyone out the doors without any serious injuries, but as Martina McBride put it:
Well she lit up the sky that fourth of July
By the time that the firemen come
They just put out the flames, and took down some names...

...and took what was left of the plane to the scrap yard.

Moral of the story is in an emergency, doing the right thing in a timely but not excessively hasty manner is almost always more important than doing something really, really fast and maybe doing it wrong.

Or as my old CAG CAPT Foster S. "Tooter" Teague (aka "The Bossier City Bearcat") used to say, "When an emergency happens, first thing you do is wind the clock in the panel -- then start doing the procedure calmly, coolly, and professionally." If the plane comes apart in that amount of time, you weren't going to save it anyway, but you may prevent yourself from screwing the pooch in your haste.
 
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I have a friend that used to own a Navajo, he was low time ME pilot and luckily his MEI was with him when he departed with a load of JET-A!! :yikes:
I think they got to 1200 feet or so, lost both engines in pretty quick succession, but did make it back to the runway unharmed, no damage except the two engines, which the FBO gladly replaced.:D
 
Well, maybe, but don't rush it. Old story about an overly hasty BOAC crew...

Hot (at least by British standards) summer afternoon in London, England. A BOAC 707 (which dates the story two ways) is departing Heathrow for New York (JFK? maybe still Idlewild then? :dunno:). Summer means lots of folks visiting England, so the flight is chock full, and with range of a 707 and the winds on a westbound transatlantic flight, the fuel tanks are equally full. Right after takeoff, they get a fire light on the #1 engine. The crew leaps into action, and performs what is, according to the CVR, the fastest engine shutdown drill ever seen in training or operational experience...


...on the #2 engine.


Oops.

Problem now is that once you pull the E-handle on a 707, the fuel shutoff valves in the pylon are irrevocably closed -- only way to re-open them is to go out there with a wrench, and unlike the old China Clippers PanAm used to fly, that's not an option on a 707, so #2 is on the bench for the rest of the match. Further, fully loaded, with two engines out on the same side, the 707's Vmc is faster than you can go and still have any climb capability, so now they can't shut down #1 and still make it back to the runway.

As they say over there, "Bugger."

The crew bites the bullet, keeps #1 running, hollers for help, and bends the plane back around to the runway visually. They land it OK, and finally pull the #1 E-handle (as well as #3 and #4 as part of the emergency evacuation drill), but by then the fire has spread above the #1 pylon to the wing, so there was no stopping that show. They did get everyone out the doors without any serious injuries, but as Martina McBride put it:
Well she lit up the sky that fourth of July
By the time that the firemen come
They just put out the flames, and took down some names...

...and took what was left of the plane to the scrap yard.

Moral of the story is in an emergency, doing the right thing in a timely but not excessively hasty manner is almost always more important than doing something really, really fast and maybe doing it wrong.

Or as my old CAG CAPT Foster S. "Tooter" Teague (aka "The Bossier City Bearcat") used to say, "When an emergency happens, first thing you do is wind the clock in the panel -- then start doing the procedure calmly, coolly, and professionally." If the plane comes apart in that amount of time, you weren't going to save it anyway, but you may prevent yourself from screwing the pooch in your haste.

On the B707 the fire handles are either on the forward glare shield or mounted on the overhead panel. Either way they work the same, that is when a fire is detected on loop A or Loop B the handle lights up (RED) and the fire bell goes off.

The "fire light" on the #1 engine would light the fire handle as it's one in the same. It would be pretty hard to see the #1 handle light up bright red with the fire bell going off, and reach up and pull the #2 handle (not lit up). :rolleyes2:

Now let's discuss the procedure, the "engine shut down drill" as you called it. In a transport aircraft no one is going to move a thrust lever, pull a thrust lever back or move a fuel cutoff without a confirmation. This isn't a one man show.


Further, fully loaded, with two engines out on the same side, the 707's Vmc is faster than you can go and still have any climb capability, so now they can't shut down #1 and still make it back to the runway.

The B707 has a fuel dump system. Also, the aircraft is certified to fly with 2 engines inop on the same side, so I'm not sure where the "VMC is faster than you can go" comment comes from, certainly not Boeing. :dunno:

I went back and looked up the B707 accidents with BOAC (British Airways) and your story isn't there. There is this story about an engine fire on a BOAC 707.

Boeing_707-123_B_1959_Cockpit_zpsc4eab6ec.jpg
1446594_zps9761fa6c.jpg
 
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I would have said only an idiot could feather the wrong engine, until I did it. It was in the sim and with plenty of distractions, but it sure made the point.
 
On the B707 the fire handles are either on the forward glare shield or mounted on the overhead panel. Either way they work the same, that is when a fire is detected on loop A or Loop B the handle lights up (RED) and the fire bell goes off.

The "fire light" on the #1 engine would light the fire handle as it's one in the same. It would be pretty hard to see the #1 handle light up bright red with the fire bell going off, and reach up and pull the #2 handle (not lit up). :rolleyes2:

Now let's discuss the procedure, the "engine shut down drill" as you called it. In a transport aircraft no one is going to move a thrust lever, pull a thrust lever back or move a fuel cutoff without a confirmation. This isn't a one man show.
I agree. Nevertheless, according to the professor from Cranfield Institute who studied the accident, they managed in their haste to get it wrong.

The B707 has a fuel dump system. Also, the aircraft is certified to fly with 2 engines inop on the same side, so I'm not sure where the "VMC is faster than you can go" comment comes from, certainly not Boeing. :dunno:
According to my professor, while control can be maintained in level flight, the 707 loaded that heavily lacks sufficient excess thrust on the two remaining engines to climb at Vmc for two engines inoperative on the same side.

Beyond that, you'd have to ask Prof. Patrick Waring at Cranfield Instritute (now Cranfield University) in the UK, although that might be difficult as I believe he died a few years ago. I'm just quoting from my class notes circa 1984.
 
Ron, do you have specific data that suggests you'll destroy an engine taking it from full power to feather immediately? I've done similar exercises to that in test cells, along with running at all kinds of points you're not supposed to. While I'd not state those actions were good for the engine, I never had a crank fail.
 
I agree. Nevertheless, according to the professor from Cranfield Institute who studied the accident, they managed in their haste to get it wrong.

According to my professor, while control can be maintained in level flight, the 707 loaded that heavily lacks sufficient excess thrust on the two remaining engines to climb at Vmc for two engines inoperative on the same side.

Beyond that, you'd have to ask Prof. Patrick Waring at Cranfield Instritute (now Cranfield University) in the UK, although that might be difficult as I believe he died a few years ago. I'm just quoting from my class notes circa 1984.

Your Professor was full of it. The incident can't be found in any database, and since it's a US produced aircraft, an accident of this magnitude would have been investigated by the NTSB.

And for anyone who's familiar with the systems and procedures, they know better. :rolleyes2:
 
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Ron, do you have specific data that suggests you'll destroy an engine taking it from full power to feather immediately? I've done similar exercises to that in test cells, along with running at all kinds of points you're not supposed to. While I'd not state those actions were good for the engine, I never had a crank fail.
You will destroy the engine? No. You could cause enough damage to the engine by feathering with full throttle that you don't have enough power for OEI flight? I think that's a given.
 
Your Professor was full of it. The incident can't be found in any database, and since it's a US produced aircraft, an accident of this magnitude would have been investigated by the NTSB.
Never researched it personally, just took it as good advice. And whether it's accurate or not, I'm sure you won't argue with the object lesson, either.
And for anyone who's familiar with the systems and procedures, they know better. :rolleyes2:
After reading a lot of years of accident reports involving air carrier crews, I'm not willing to accept that they all "know better". How could an airline crew descend to 1900 feet 30 miles NW of Dulles inbound to RWY 12? How could an airline crew not see a localizer "OFF" flag? How could an airline crew run themselves out of gas working a gear problem? :dunno: And the list goes on...and those were all 3-person crews, too. :sad:
 
Never researched it personally, just took it as good advice. And whether it's accurate or not, I'm sure you won't argue with the object lesson, either.
After reading a lot of years of accident reports involving air carrier crews, I'm not willing to accept that they all "know better". How could an airline crew descend to 1900 feet 30 miles NW of Dulles inbound to RWY 12? How could an airline crew not see a localizer "OFF" flag? How could an airline crew run themselves out of gas working a gear problem? :dunno: And the list goes on...and those were all 3-person crews, too. :sad:

Ron,

The fire handle lights up RED. Even a complete dumbass will look up, see a bright red handle and think "Duh, that's the one on fire!" And the second guy that will verify before pulling it will also notice bright RED handle versus the non lit handles.

Since you do so much reading of accident reports, please do us a favor and locate the report on your supposed story. I tried, and it's nowhere to be found.

Sorry, your tale just don't make sense as it's full of very inaccurate information.
 
You will destroy the engine? No. You could cause enough damage to the engine by feathering with full throttle that you don't have enough power for OEI flight? I think that's a given.

Well, I'd not be convinced it's a given.
 
I've been an ME instructor a long time, and I've never heard of anyone recommending using the prop lever to verify.

Not really using prop to verify, but either Simcom or FSI (can't recall which) has been teaching high performance piston guys for a while now to put the hand on the prop levers after selecting gear up. The idea being that in the event of a catastrophic failure during the initial climbout, you go straight from identify to feather- pull the prop back to feather on the side the nose yaws to.
 
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