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swisster

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Shouldn't the skid marks be straight? Or did he land it with power-on?? If so, it worked out okay but it was owed more to luck than proper emergency procedures for loss of tail rotor thrust.

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swisster:

People fly airplanes, pilots fly helicopters

 

By the way, Swisster, I fly airplanes as well as helicopters; what does that make me? Why the fixed-wing snobbery?

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Almost looks like he tried to bring it to a hover before putting it down. Either that or he WAS in a hover when it happened. Either way... pretty crazy.

 

Here's a thought provoking question for you guys. Assume forward flight, 70 kts or so. Tail rotor and it's gearbox goes flying off the aircraft. Other than the yaw and the now missing seat cushion, what else happens?

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Almost looks like he tried to bring it to a hover before putting it down. Either that or he WAS in a hover when it happened. Either way... pretty crazy.

 

Here's a thought provoking question for you guys. Assume forward flight, 70 kts or so. Tail rotor and it's gearbox goes flying off the aircraft. Other than the yaw and the now missing seat cushion, what else happens?

In an R44?

http://www.robinsonh...2008_summer.pdf

 

see page 3

 

"At 40 knots he executed a running landing, skidding 45 meters and stopping without injuring himself or fur- ther damaging the helicopter. "

 

 

The newsletter doesn't go into detail how the landing was performed, but I am pretty sure that there would still be some right yaw even at 45kts. My guess is that he was rolling the throttle off while touching down, at least that's how it is taught down here. This is a pretty tricky and risky manoeuvre to practice though, I personally don't like doing it.

Edited by lelebebbel
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Here's a thought provoking question for you guys. Assume forward flight, 70 kts or so. Tail rotor and it's gearbox goes flying off the aircraft. Other than the yaw and the now missing seat cushion, what else happens?

 

You lose anti-torque first thing, any streamlining will be by the vertical fin. However, even with 'neutral' pitch you lose the t/r disc's effect, you'll torque a bit.

Your cg shifts forward, the nose drops. Hopefully, new trim balance point is controllable and you didn't jerk the cyclic aft when the nose pitched down and chop your tailfeathers off.

The helo will roll, uh- forward, as it torques. Speed and power are now your yaw control, because the EFFING PEDALS ARE USELESS! Your head tells you that you can relax pressure on the pedals, but one is conditioned to do so...

You do the emergency procedure.

 

Pretty much the same in a hover except the yaw won't stop until the power is chopped with throttle or collective (Astar).

 

An adult beverage is appropriate at this point.

Edited by Wally
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lele: How is it performed? Roll throttle off as required to control yaw and raise collective to maintain the loss of lift from decreased RPM?

 

Wally: EP in the R-22 is to basically do a full down auto. I imagine it isn't too much different in other aircraft. What I was trying to get at was the CG shift that you mentioned. I know the horizontal stabilizer will keep the nose from dropping excessively while at speed, but how much nose drop can one expect? Will there be enough aft cyclic remaining to actually complete the flare portion of the auto?

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Wally: EP in the R-22 is to basically do a full down auto. I imagine it isn't too much different in other aircraft. What I was trying to get at was the CG shift that you mentioned. I know the horizontal stabilizer will keep the nose from dropping excessively while at speed, but how much nose drop can one expect? Will there be enough aft cyclic remaining to actually complete the flare portion of the auto?

 

I've never flown a Robbie, no idea of cyclic margin if your tailrotor/gearbox departs the aircraft. I would try to get to somewhere where some run on/yaw wouldn't roll you over, but it's a "survival first" situation if and when you have stuff flying off the aircraft. Sometimes survival is as much as you can hope for, sacrifice the airframe to ensure that happens- fly the pig as far into the crash as you can.

Hovering autos should be second nature, one thing I hate about the Astar is the ECL on the floor.

Edited by Wally
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Cyclic margin, I was just asking in general terms. The air crash investigation show that went on about the bird that crashed in the North Sea due to a lightning strike to the TR basically made it seem like if the TR had separated entirely there was no recovering. I know TV shows need to throw things like that in there for the shock value, but it made me wonder.

 

ECL?

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Here is the 2 page Stuck Pedal Procedure I have. For Left pedal it's not necessary to run it on. Careful arrival at the hover and small RRPM reduction will make a nice hover landing. The Right pedal requires a hover auto after arriving at hover altitude with no airspeed.

 

 

 

I seem to recall the good old lucky Left - rotten Right method for stuck pedal.

 

Are they still teaching stuck – restricted pedals this way or have they redesigned the wheel again?

 

FOR WHAT IT IS WORTH AND NOT TO REPLACE INSTRUCTION IN YOUR ACTUAL A/C.

 

This is my remembrance of the patter:

 

If you are able to control the A/C you have time to take a look at the problem while proceeding to a suitable run on area- check that nothing is obstructing pedal movement (aside from the instructor). - Attain 70-80 KTS - (we are talking 206 - 205 - 212 here) and level flight.

 

Look at which side the ball is on if not centered. Go to the opposite side - ball centered or Left go to the Right - you have a rotten Right which will require a LOW Power applied landing - the more the ball is off center the more exiting the problem of apt to be.

 

If the ball is off to the Right - go Left - you have a lucky Left and a landing with higher power applied is possible - once again the more the ball is out the (Better) worse the problem.

Having done this a plan is required

 

 

ROTTEN RIGHT LUCKY LEFT

 

 

Being as you have no “Pause”, “Exit” or “Save Game” function you are going to have to do something.

 

Actions such as whining on the radio (aside from the gathering of interested spectators, some with unhelpful advice, some with cameras and still others with forms to be filled out once the motion stops), cursing your career choices, and prayer, while comforting, are not immediately helpful.

 

Let's deal with lucky Left - more power is going to keep the nose straight.

Perhaps there is enough Left pedal to align the A/C with the runway for a low speed run on.

Perhaps there is so much Left pedal that a hover can be attained- this would be nice.

Perhaps however the pedal is stuck at a position which would give you a Left turn even in the hover.

 

Well, a lower RPM will reduce TR effectiveness, so once arriving on final approach let's reduce throttle (S) to reduce RPM to the bottom of the green Arc.

 

Let's also assume you have a good run on area.

 

Make very sure that the throttle friction(s) are set as to allow free movement – the inability to move the throttle (S) at the bottom can lead to fascinating problems.

 

 

Fly a normal approach with the nose off to the left; slowly reduce the airspeed to arrive over the end of the area at 30 Kts and 2 - 5 feet. If, on initial approach, the nose starts Right as you decelerate and pull power you may have misdiagnosed the problem and are dealing with a rotten right. Go around early and rethink.

 

Over the runway: Put the helicopter in a 5-10 Deg nose up attitude and let it decelerate, as it does apply collective to keep the a/c just off the ground.

As the helicopter decelerates the power applied should cause the nose to align (come right) with the runway. When aligned allow the a/c to touch down and come to a stop. Then slowly lower the collective while closing the throttle(S). Once aligned don’t allow the A/C to decelerate further or the nose will go Right – if this happens close the throttle as required to keep aligned – accept the run on.

If the A/C comes to a hover slowly lower the collective to land, if needed open / close the throttle a bit to keep the nose straight.

If the a/c comes to a very low hover and the nose starts Left twist the throttle towards open reasonably quickly - this should cause the nose to stop or even swing Right - put the darn thing down.

If all this is unsuccessful and the nose is still turning Left pull collective while slowly closing the throttle - RPM and tail rotor effectiveness will decrease and should stop the rotation - if not allow the a/c to touch down before the rpm decreases too much. A little rotation on touchdown should not be a problem if you are in a stable hover over the mythical "Hard Smooth Surface''

If the problem is a lot of Left pedal a Right xwind will help. Don't put it at more than 45 degrees or you could end up downwind if the a/c rotates left.

 

If you have full Left pedal in when it stuck you are going to need to pull a lot of power to stop the rotation. Good example is a student and instructor doing outo circuits – Student rotates and applies max power to attain a fast climb back to auto altitude. A lot of Left pedal is applied – cruel instructor freezes pedal – A/C now has enough Left pedal to spin Left like a top in the hover at the low gross weight. “Houston- We have a problem!”

 

 

 

 

 

Let’s visit the rotten Right scenario:

 

Once again the more the ball is deflected the worse the problem is likely to be.

 

Set yourself up at 1000 ft for a steep approach at normal approach speed – (60 -70 Knots in a 212.) If not sure of yourself start your approach even higher to allow lots of time to set yourself up or go around – don’t let the speed drop too far before making a decision to go around.

 

Make very sure that the throttle frictions are set as to allow free movement – the inability to close the throttle (S) at the bottom can lead to fascinating even mesmerizing problems.

 

Lower the collective until the nose is Left of your approach track.

 

If you get the collective all the way down and your nose is still Right you may need to close the throttle and do an autorotation. Before doing this – perhaps you misdiagnosed the problem – if able go around and rethink.

 

We will assume that the nose came left.

 

Continue the approach to the runway. Maintain your speed.

 

Do a reasonably hard flare at the bottom. This should require the collective to be lowered further and the nose to go further left. As you decelerate and pull collective to arrest your rate of sink the nose will start coming right. Co-ordinate your activities in order to set the a/c down as the nose aligns with the runway and close the throttle as necessary to remain aligned with the runway.

Remember to level the A/C so as not to scrape the tail.

 

Remember that this is for stuck pedals.

 

Loss of tail rotor or the drive thereto will probably require an immediate autorotation to whatever destination is immediately below you.

That is another kettle of fish altogether.

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It's 1/4 mile in heavy snow and freezing fog right now. The kind of day I could've had a beer for breakfast! A little bored so had the time to find a previous thread on stuck pedals. MikeMV had some great advice. As you can tell I'm not an advocate of high speed run on landings. Of course reverse everything in an Astar and wish the throttle was on the collective!

 

http://helicopterforum.verticalreference.com/topic/11654-stuck-pedals/page__hl__+lucky%20+left%20+rotten%20+right#entry84132

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ECL?

 

Engine Condition Lever.

Looks like a rotor brake lever with a button (starter ) on it. Overhead in most twins, on the floor between the seats (rotor brake, ECL, fuel shutoff valve) on a AS350B2 and earlier. Acts just like a throttle, and in moments of confusion I call it that.

The emergency procedure for loss of tail rotor thrust is collective down and land before yaw speed... uh, yeah. Fortunately the tail rotor is heck for stout and stuck on real good. Seen vertical/horizontal stabs shake loose/break spars before the TR GB detached.

Edited by Wally
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In an R44?

http://www.robinsonh...2008_summer.pdf

 

see page 3

 

"At 40 knots he executed a running landing, skidding 45 meters and stopping without injuring himself or fur- ther damaging the helicopter. "

 

 

The newsletter doesn't go into detail how the landing was performed, but I am pretty sure that there would still be some right yaw even at 45kts. My guess is that he was rolling the throttle off while touching down, at least that's how it is taught down here. This is a pretty tricky and risky manoeuvre to practice though, I personally don't like doing it.

 

Its interesting that the pilot in that article didn't perform an auto landing as prescribed in POH for "loss of tailrotor thrust"!

 

What would cause the tail rotor to just come off?

 

In his case, something flew out the door and ripped it off, other than that, who knows?

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lele: How is it performed? Roll throttle off as required to control yaw and raise collective to maintain the loss of lift from decreased RPM?

 

Pretty much. If you raise the collective, make sure to keep rolling the throttle off while doing so (or chop it right off into the overtravel spring like a hover auto). If you try to compensate the loss of RPM by raising collective with the engine on, you will end up with MORE right yaw, not less. The helicopter should be touching down while the throttle is being rolled off.

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Pretty much. If you raise the collective, make sure to keep rolling the throttle off while doing so (or chop it right off into the overtravel spring like a hover auto). If you try to compensate the loss of RPM by raising collective with the engine on, you will end up with MORE right yaw, not less. The helicopter should be touching down while the throttle is being rolled off.

 

Sounds like a good way to snap the MR blades off if you have much altitude. Adding collective will decrease RPM, not increase it.

 

Perhaps I missed something and you are referring to a hover auto?

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Sounds like a good way to snap the MR blades off if you have much altitude. Adding collective will decrease RPM, not increase it.

 

Perhaps I missed something and you are referring to a hover auto?

 

 

You don't do that at 1,000ft of course. What I am describing happens at 1ft above the ground and finishes in a run on landing, hopefully straight. It could be described as a slow-motion hovering auto.

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You're never going to be able to write out the procedures for all tail rotor emergencies you may face. We did quite a few practice tail rotor emergencies in flight school, both in the simulator and in the actual aircraft. Some of them you got the nose straight with throttle, others airspeed, others you were at a hover, some required autorotation...

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You're never going to be able to write out the procedures for all tail rotor emergencies you may face. We did quite a few practice tail rotor emergencies in flight school, both in the simulator and in the actual aircraft. Some of them you got the nose straight with throttle, others airspeed, others you were at a hover, some required autorotation...

 

Indeed. Even with the same mechanical failure, the results (and required action) are going to be very different depending on gross weight, altitude, wind, C of G etc.

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While in Guam, I met a dude who had an inflight tail rotor failure in a B47 while flying off a tuna boat. He said, as he was trucking along when he felt a vibration in the pedals and then a loud bang. After the bang he noticed he had lost yaw control which required a sideslip to remain aloft. While maneuvering to get close to the boat, he noticed the Korean Captain sitting next to him undue his seatbelt. He told the Captain to keep his seat belt on. The Captain complied. While circling to limit the side-slip, the pilot said he couldn’t remember the procedure for the particular 47 he was flying (apparently one model says to run it on while another says to auto). He eventually decided to descend an attempt to put in down (in the open ocean). While descending and focusing on the task at hand, at about 200 feet, the pilot looked to his right and saw the bottom of the Captains sandals as they cleared the floats. Shocked the Captain had bailed out; he continued to descend and just prior to touching down the machine began to spin when he blacked out. He said when he came to; the machine was idling upright, floating, and blades slowly spinning down. He had no recollection of how he got there…..

 

After a few hours of maneuvering the boat to wench the helicopter back onto the deck, he entered the galley to see his Captain on a table dead and the crew attempting to revive him with acupuncture. He said it was a real bummer to returning to port with the Captain in the freezer……..

Edited by Spike
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