Tail Rotor Problems
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Tail Rotor Problems
Tail rotor problems can take many forms. You can have a complete loss of T/R drive, requiring an Auto or many different combinations of problems, i.e. Aux Hyd/mixing unit problems in a 61, Cable jam/failure in a 76, fixed pitch problems and so on.
So lets hear from everyone about their ideas or thoughts about these types of problems. You don't have to have any actual T/R fail experience to contribute, only a desire to learn more on the topic. All are welcome.
Let the games begin!
Cheers, OffshoreIgor
So lets hear from everyone about their ideas or thoughts about these types of problems. You don't have to have any actual T/R fail experience to contribute, only a desire to learn more on the topic. All are welcome.
Let the games begin!
Cheers, OffshoreIgor
Last edited by Heliport; 7th Mar 2006 at 18:01.
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Ok, My opinion is that anyone with only a minimum amount of hours ie less than about two hundred, is going to be very lucky to walk away from a tail rotor failure of any type unless they're very lucky.
Saying that, it wouldn't make much difference if you had thousands of hours if the conditions were against you.
What would happen while doing sling load ops, low airspeed, hilly terrain. Might not be your best days flying!!
Saying that, it wouldn't make much difference if you had thousands of hours if the conditions were against you.
What would happen while doing sling load ops, low airspeed, hilly terrain. Might not be your best days flying!!
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OK, your point is well taken. However, I think a low time pilot may fair better than you think simply because he/she has probably been practicing them alot more recently than those of us who may or may not practice them once a year during recurrent training.
I for one have not had a simulated T/R drive failure in years. The closest we train to it is a jammed pedal or simulated cable failure on the 76/61.
Granted, experience may enable a calm, collected pilot to react better to a given situation, however, as you say, it may not be your day/night! i.e. Enroute to the rig at night over water and bang!!! Just look at the result of the 212 in the Maldives, that lost the T/R after the Co-Pilot's door was jetisoned in preperation for ditching! Not a good thing!
Food for thought. Cheers, OffshoreIgor
I for one have not had a simulated T/R drive failure in years. The closest we train to it is a jammed pedal or simulated cable failure on the 76/61.
Granted, experience may enable a calm, collected pilot to react better to a given situation, however, as you say, it may not be your day/night! i.e. Enroute to the rig at night over water and bang!!! Just look at the result of the 212 in the Maldives, that lost the T/R after the Co-Pilot's door was jetisoned in preperation for ditching! Not a good thing!
Food for thought. Cheers, OffshoreIgor
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an instructor of mine once demonstrated an interesting technique for a TR failure: begin with the shallow approach, minimizing maneuvering and power application, and if possible with a left crosswind (american helos and the like). As airspeed is bled off, the nose wants to turn right but if sufficient speed is held (and hopefully if the left crosswind is present) you will be able to continue toward your spot without actually rotating. now the tricky part, as speed gets really low and you are about where you want to be, maybe at a height equivelant to a high hover (and with the nose getting close to making you wonder why you are trying at all anymore) zero the airspeed as much as possible and hold the ship level while rolling off the throttle- from here you have more or less a basic hovering autorotation- waiting for the helo to settle then applying pitch (with the throttle held at idle to prevent more spinning). The main idea is to get to your spot without the nose getting farther than 90 degrees off of your path. This maneuver seems more compilcated than necessary, but might be just the thing into an area not suited for a ground slide.
[This message has been edited by lmlanphere (edited 13 February 2001).]
[This message has been edited by lmlanphere (edited 13 February 2001).]
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On paper ...when you start to read this it may come across rather fussy or complicated.
But - in practice the Loss of the TR Drive is fairly final it's going to require a bloody swift reaction, to be able to engine off from the hover in order to have a chance of being in a attitude to achieve a decent cushioned landing. In forward flight - well if you manage to contain the yaw you might be able to postion (using low power or suitable PWR/IAS combo) the helo to a safe area for an EOL or you'll just have to enter auto, shutdown the engines and accept an interest EOL at the bottom. All very challenging and something I would rather not try unless I was in a sim.....that said if I was on the NOTAR I suppose I wouldn't have the problem ....probably something else to think about though ....I'm sure.
Now - If you have a Tail Rotor control failure
There's quite alot you can achieve. If you take your time:
1. Define the problem - is it AFCS, Hydraulics, a jam, cable snap or somebody's bag rat wedged behind the pedal. It could be as simple as that - somebody's FOD.
2. Check fuel - if you've got loads we can take all the time in the world to get it right, if not then you'll have to do the same assessments but with a sensible level of alacrity.
3. You need to consider what configuration the jam or failure has left for you to deal with. Is it either:
1. low power controlled flight (pedal Positon)
or
2. High Powered controlled flight (pedal pos'n)
I make this broad assessment criteria based on the position of the applied pedal at the time of the problem first coming to light.
The pedal applied will vary as to type and MR blade rotation.
First of all you need to do a handling check:
which should take the following form:
1. Maintain Wings level
2. Fly at Min power speed (usually 60-70kts)
3. Using collective apply a power setting that will bring the 'ball' in to the centre.
Don't concern yourself with collective and power settings too much.
Then check you RCDI and note the following
A. LOW POWER pedal situation -
for example: you find you have Wings level, Ball in middle and a ROD of 1000'/ min
This means that you could return to a large grass field in a skidded helo or a large runway in wheeled helo and carry out a pre-briefed auto or low powered descent to the ground touchng down at up to approx 60 knots and smoothly shutting down the engine(s) as you enjoy the rutted camel ride from hell across the airfield or you can differentially break if you have them fitted - Luxury. Now a 60kt touch down is very saucy but, in many aircraft a, doable get out of jail type manoeuvre. Obviously - a high wind day of 30 knots straight down your landing area is going to help immensely.
This is good news - you can now decide whether you want to do another handling check to see if you can still maintain your Wings level ball in middle at a slower speed and lower rate of descent. Who knows .....but if you have the fuel keep trying.
B. HIGH POWER PEDAL situation -
Lets do the handling check again -
WINGS LEVEL and put the BALL IN THE CENTRE with collective and find out where the power ends up. Lets say it provides the worse case scenario of a power higher than that required to hover.
We already know that the if we bring the IAS back towards a very low IAS that the PWR REQ'D will increase. As we decel we continue to try to maintain - WINGS LEVEL,BALL IN MIDDLE now by pulling collective to maintian our condition.
We see that we are climbing slowly - so what can we vary ?
1. Weight - it's reducing as we burn fuel ..so it ain't helping us
2. Even less IAS almost or even hovering .....but once we reach this we're at a point where the power req'd is now a MAX value.....but we are still climbing slowly.
3. Nr - if we vary Nr by way of a carefully controlled brief to co-pilot or crew member or self brief by the single pilot we can retard the throttle or SSL's to start a controlled reduction of Nr thus reducing Total Rotor Thrust - but maintaining useful power on Nr values. You should practice this before attemting the approach. If the Nr should decay too much too early use lever t regain Nr until you have had time to apply a little more throttle. Try to aim for a ROD around 200-300'/min
Your approach config should be practiced at altitude above your intended LS and your approach planned so that you start on an extraordinary long final (terrain dependant of course)to achieve a short final by approx 300 - 500' where you are continuing to reduce speed progressively and controlling your reduced Nr to give you a ROD around 200-300'per min at this stage on the approach the aircraft will not be pointing straight or wings level until you reach your IAS you assessed earlier. However, as you approach the hover you will have ground effect to contend with and will have to further reduce the Nr (retarding throttles and SSL's even further. As you approach the Hover or low speed you should aim to be satisfied with your heading, attitude and sink rate ...if so then smoothly retard the levers/lever or twist off the remaining power nice'n'gently and the helo will descend through the GE and you can .....shutdown and go back to the bar for several beers.
During both of these procedures you can always throw it away if you need to...... accepting the awkward manner of flight that you will achieve (out of balance wing low etc) Climb up, line yourself up again and practice it all over again - provided you haven't had to do the Engine OFf bit that is.
I have taught these techniques as have many other instructors - I'm sure, but the problems above are worth practising. If you've ever had a birdstrike that was big and it came through the perspex and wrapped it's wings and colon around your pedals ...you will want to have tried this at some point.
One important point tho' is don't get too wrapped up inside the cockpit it is possible to fly reasonably normally during the preparation and positioning. But at the end if it looks right outside the cockpit, the chances are everything will be alright so keep looking out and flying the beast.!!!
Sorry if it's long winded or if it's stuff you already know......I'm probably the only mug trying to attempt to paint the picture on paper..... back to my Guiness byeeee
[This message has been edited by eden (edited 13 February 2001).]
[This message has been edited by eden (edited 13 February 2001).]
But - in practice the Loss of the TR Drive is fairly final it's going to require a bloody swift reaction, to be able to engine off from the hover in order to have a chance of being in a attitude to achieve a decent cushioned landing. In forward flight - well if you manage to contain the yaw you might be able to postion (using low power or suitable PWR/IAS combo) the helo to a safe area for an EOL or you'll just have to enter auto, shutdown the engines and accept an interest EOL at the bottom. All very challenging and something I would rather not try unless I was in a sim.....that said if I was on the NOTAR I suppose I wouldn't have the problem ....probably something else to think about though ....I'm sure.
Now - If you have a Tail Rotor control failure
There's quite alot you can achieve. If you take your time:
1. Define the problem - is it AFCS, Hydraulics, a jam, cable snap or somebody's bag rat wedged behind the pedal. It could be as simple as that - somebody's FOD.
2. Check fuel - if you've got loads we can take all the time in the world to get it right, if not then you'll have to do the same assessments but with a sensible level of alacrity.
3. You need to consider what configuration the jam or failure has left for you to deal with. Is it either:
1. low power controlled flight (pedal Positon)
or
2. High Powered controlled flight (pedal pos'n)
I make this broad assessment criteria based on the position of the applied pedal at the time of the problem first coming to light.
The pedal applied will vary as to type and MR blade rotation.
First of all you need to do a handling check:
which should take the following form:
1. Maintain Wings level
2. Fly at Min power speed (usually 60-70kts)
3. Using collective apply a power setting that will bring the 'ball' in to the centre.
Don't concern yourself with collective and power settings too much.
Then check you RCDI and note the following
A. LOW POWER pedal situation -
for example: you find you have Wings level, Ball in middle and a ROD of 1000'/ min
This means that you could return to a large grass field in a skidded helo or a large runway in wheeled helo and carry out a pre-briefed auto or low powered descent to the ground touchng down at up to approx 60 knots and smoothly shutting down the engine(s) as you enjoy the rutted camel ride from hell across the airfield or you can differentially break if you have them fitted - Luxury. Now a 60kt touch down is very saucy but, in many aircraft a, doable get out of jail type manoeuvre. Obviously - a high wind day of 30 knots straight down your landing area is going to help immensely.
This is good news - you can now decide whether you want to do another handling check to see if you can still maintain your Wings level ball in middle at a slower speed and lower rate of descent. Who knows .....but if you have the fuel keep trying.
B. HIGH POWER PEDAL situation -
Lets do the handling check again -
WINGS LEVEL and put the BALL IN THE CENTRE with collective and find out where the power ends up. Lets say it provides the worse case scenario of a power higher than that required to hover.
We already know that the if we bring the IAS back towards a very low IAS that the PWR REQ'D will increase. As we decel we continue to try to maintain - WINGS LEVEL,BALL IN MIDDLE now by pulling collective to maintian our condition.
We see that we are climbing slowly - so what can we vary ?
1. Weight - it's reducing as we burn fuel ..so it ain't helping us
2. Even less IAS almost or even hovering .....but once we reach this we're at a point where the power req'd is now a MAX value.....but we are still climbing slowly.
3. Nr - if we vary Nr by way of a carefully controlled brief to co-pilot or crew member or self brief by the single pilot we can retard the throttle or SSL's to start a controlled reduction of Nr thus reducing Total Rotor Thrust - but maintaining useful power on Nr values. You should practice this before attemting the approach. If the Nr should decay too much too early use lever t regain Nr until you have had time to apply a little more throttle. Try to aim for a ROD around 200-300'/min
Your approach config should be practiced at altitude above your intended LS and your approach planned so that you start on an extraordinary long final (terrain dependant of course)to achieve a short final by approx 300 - 500' where you are continuing to reduce speed progressively and controlling your reduced Nr to give you a ROD around 200-300'per min at this stage on the approach the aircraft will not be pointing straight or wings level until you reach your IAS you assessed earlier. However, as you approach the hover you will have ground effect to contend with and will have to further reduce the Nr (retarding throttles and SSL's even further. As you approach the Hover or low speed you should aim to be satisfied with your heading, attitude and sink rate ...if so then smoothly retard the levers/lever or twist off the remaining power nice'n'gently and the helo will descend through the GE and you can .....shutdown and go back to the bar for several beers.
During both of these procedures you can always throw it away if you need to...... accepting the awkward manner of flight that you will achieve (out of balance wing low etc) Climb up, line yourself up again and practice it all over again - provided you haven't had to do the Engine OFf bit that is.
I have taught these techniques as have many other instructors - I'm sure, but the problems above are worth practising. If you've ever had a birdstrike that was big and it came through the perspex and wrapped it's wings and colon around your pedals ...you will want to have tried this at some point.
One important point tho' is don't get too wrapped up inside the cockpit it is possible to fly reasonably normally during the preparation and positioning. But at the end if it looks right outside the cockpit, the chances are everything will be alright so keep looking out and flying the beast.!!!
Sorry if it's long winded or if it's stuff you already know......I'm probably the only mug trying to attempt to paint the picture on paper..... back to my Guiness byeeee
[This message has been edited by eden (edited 13 February 2001).]
[This message has been edited by eden (edited 13 February 2001).]
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ImIanphere,
(Sorry if I've got your ID wrong as I can't tell if they are Is or ls!)
Although your T/R drive loss technique may work on an R-22 or other small single piston-engined aircraft it might not be applicable to turbine engined ones, if only for the reason that they often don't have throttles that are within reach of a pilot with his hands full of sticks. Co-ordination then becomes a problem if a second crew member is not available (or present)to assist.
I have flown a lot of time in one aircraft type that is very likely go out of control if autorotation is not entered immediately and both throttles subsequently chopped before flaring to land; the only sure speed / power combination being nil power and 75 to 80 kts in autorotation. I did a lot of time carrying out simulator training on this type [both in the hot seat and operating the sim from down the rear] and the experiences of those unlucky enough to try it for real confirm what we found. Simulators are not always accurate because they depend on good data being programmed into them. If that's not available then an "off model" best guess is put into the software programme by the designer.
The AFM usually gives some guidance but can't be relied on as gospel 'cos manufacturers don't often practice it deliberately for obvious reasons.
-----------------------------------------
In the case of a cable jam /partial loss of control of T/R pitch where a powered approach is being considered:
As one who has flies American and European aircraft (different directions of main rotor rotation), to help prevent any confusion with phrases such as "Lucky Left" or "Right is Right" (depending which type I am flying) I now simply remember which side the retreating blade is on (I tend to remember this from the start-up)! This side is then the good side to have the nose "cocked off" towards on the approach. As collective is increased to cushion the (powered)touchdown, the nose will come round, from increased Tq reaction, to point straight ahead. The retreating blade side is also the good side to have the crosswind coming from.
Hope this helps the discussion.
ShyT.
(Sorry if I've got your ID wrong as I can't tell if they are Is or ls!)
Although your T/R drive loss technique may work on an R-22 or other small single piston-engined aircraft it might not be applicable to turbine engined ones, if only for the reason that they often don't have throttles that are within reach of a pilot with his hands full of sticks. Co-ordination then becomes a problem if a second crew member is not available (or present)to assist.
I have flown a lot of time in one aircraft type that is very likely go out of control if autorotation is not entered immediately and both throttles subsequently chopped before flaring to land; the only sure speed / power combination being nil power and 75 to 80 kts in autorotation. I did a lot of time carrying out simulator training on this type [both in the hot seat and operating the sim from down the rear] and the experiences of those unlucky enough to try it for real confirm what we found. Simulators are not always accurate because they depend on good data being programmed into them. If that's not available then an "off model" best guess is put into the software programme by the designer.
The AFM usually gives some guidance but can't be relied on as gospel 'cos manufacturers don't often practice it deliberately for obvious reasons.
-----------------------------------------
In the case of a cable jam /partial loss of control of T/R pitch where a powered approach is being considered:
As one who has flies American and European aircraft (different directions of main rotor rotation), to help prevent any confusion with phrases such as "Lucky Left" or "Right is Right" (depending which type I am flying) I now simply remember which side the retreating blade is on (I tend to remember this from the start-up)! This side is then the good side to have the nose "cocked off" towards on the approach. As collective is increased to cushion the (powered)touchdown, the nose will come round, from increased Tq reaction, to point straight ahead. The retreating blade side is also the good side to have the crosswind coming from.
Hope this helps the discussion.
ShyT.
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Helimutt,
I might not have put over my point too well
(on the thread this disccusion began).
I wanted to start it the right place, which is to take a look at the often misused term
'TR failure' but it appears to be getting done now.
I have to say that the difference between a
true TR failure and a TR drive failure would be completely unoticeable and agree with you on that point, as the result would still be zero TR thrust to balance torque whether the blades are still on the Heli. or not.
But I think the difference between the above and jammed pedals/controls or control disconnection WOULD be clear because the Heli would not yaw right at anything like the initial rate, even if its pitch reduced to minimum. Easy on paper though, quite different in the heat of the moment and if that is where you were going then I agree with that too.
But all good training begins with fully understanding what is going on first, and that is where I began.
A good thread which I will read fully and contribute to when I have finished work.
The last time I renewed by Inst. rating in UK We did TRUE TR failure in the hover and it was surprisingly easy to master. Intersting for me because I have witnessed a
loss of TR control on an R22 in UK but more of that later.
Lovely sunny day, slingloading is today's order and I'm off to help a very able student take a heap of tyres for a flying lesson of their own! (Yes, using an R22, and within MAUW and C of G!)
I might not have put over my point too well
(on the thread this disccusion began).
I wanted to start it the right place, which is to take a look at the often misused term
'TR failure' but it appears to be getting done now.
I have to say that the difference between a
true TR failure and a TR drive failure would be completely unoticeable and agree with you on that point, as the result would still be zero TR thrust to balance torque whether the blades are still on the Heli. or not.
But I think the difference between the above and jammed pedals/controls or control disconnection WOULD be clear because the Heli would not yaw right at anything like the initial rate, even if its pitch reduced to minimum. Easy on paper though, quite different in the heat of the moment and if that is where you were going then I agree with that too.
But all good training begins with fully understanding what is going on first, and that is where I began.
A good thread which I will read fully and contribute to when I have finished work.
The last time I renewed by Inst. rating in UK We did TRUE TR failure in the hover and it was surprisingly easy to master. Intersting for me because I have witnessed a
loss of TR control on an R22 in UK but more of that later.
Lovely sunny day, slingloading is today's order and I'm off to help a very able student take a heap of tyres for a flying lesson of their own! (Yes, using an R22, and within MAUW and C of G!)
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IHL:
The CoJo was a long time friend of mine and his background was Mil. The only thing that has come out of the inquiry is that he had been trained to jettison the door prior to water contact in an imminent ditching situation. Knowing his background, I can't figure out who would advocate the door being jettisoned above translational.
From what has been published by TSB in Canada, the aircraft appeared to be returning to shore, when it went down. The initial report points to the door jettison as the cause of the loss of T/R. The door went throught the mast and then through the T/R.
As to why it was jettisoned, I guess we'll never know. I guess the best question to ask in this forum is, When should you jettison the doors. My opinion is only when you have a controlled ditching situation and only at a reduced airspeed i.e. less than 35 KIAS.
As for the responses to this topic, I think we've found a winner. No shortage of expertise here. I think this will be a real benefit to all pilots as the techniques we use on mediums and heavies are not always taught to those flying SE Light Helis. Although the same procedures will generaly work on all types.
One procedure I haven't heard yet is for a jammed pedal situation. On the 76 we teach our pilots to 'Beep Up' for a stuck right pedal and to 'Beep Down' for a stuck left pedal. The logic being, more power to reduce for the RPF (i.e. nose swings left) and more power available for the LPF (i.e. nose swings right). This technique can be equally useful for a 206, 500, 355 etc. Remember, the engine will still help you in the recovery whether it is a power reduction or power increase.
Cheers, OffshoreIgor
The CoJo was a long time friend of mine and his background was Mil. The only thing that has come out of the inquiry is that he had been trained to jettison the door prior to water contact in an imminent ditching situation. Knowing his background, I can't figure out who would advocate the door being jettisoned above translational.
From what has been published by TSB in Canada, the aircraft appeared to be returning to shore, when it went down. The initial report points to the door jettison as the cause of the loss of T/R. The door went throught the mast and then through the T/R.
As to why it was jettisoned, I guess we'll never know. I guess the best question to ask in this forum is, When should you jettison the doors. My opinion is only when you have a controlled ditching situation and only at a reduced airspeed i.e. less than 35 KIAS.
As for the responses to this topic, I think we've found a winner. No shortage of expertise here. I think this will be a real benefit to all pilots as the techniques we use on mediums and heavies are not always taught to those flying SE Light Helis. Although the same procedures will generaly work on all types.
One procedure I haven't heard yet is for a jammed pedal situation. On the 76 we teach our pilots to 'Beep Up' for a stuck right pedal and to 'Beep Down' for a stuck left pedal. The logic being, more power to reduce for the RPF (i.e. nose swings left) and more power available for the LPF (i.e. nose swings right). This technique can be equally useful for a 206, 500, 355 etc. Remember, the engine will still help you in the recovery whether it is a power reduction or power increase.
Cheers, OffshoreIgor
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The procedure I have tried to put across will work for jammed pedals, problems arising from cabling and negative force gradient spring residual problems, stuck or jammed pitch setings on the TR - in short any CONTROL you might get. We all obviously pray that we don't get the extremes of left or right - but that could be the way the cookey crumbleth.
If you run back to looking outside and seeing what the different combinations of airspeed, wings level and ball in middle as a result of lever position(thus power being used) you can determine the type of approach you need to consider.
I obviously didn't explain it very well ....never was good at this writing thing! I'll have to stick to the frantic egg whisk flying I reckon!
If you run back to looking outside and seeing what the different combinations of airspeed, wings level and ball in middle as a result of lever position(thus power being used) you can determine the type of approach you need to consider.
I obviously didn't explain it very well ....never was good at this writing thing! I'll have to stick to the frantic egg whisk flying I reckon!
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Offshore: Good on you to start this one. It would be great to hear from a 'novice' about their views on such a sinister malfunction. We always seem to hear from the same 'pro's'....
Eden: Guess who's been thru beefers school then!! Brilliant contribution..if only it was so predictable in real life!!
SPS: How on earth can you 'practice' real TR failures in the hover. Do you have a disconnect coupling in the drive train??
Thing to remember, in addition to the effects of surviving the initial bang....if the TR decides to take off, you're left with a major C of G problem [as per the story of the vietnam helo pilot who got his tail blown off with a SAM 7].
Different a/c types have their pros and cons too. Fenestrons offer advantages w.r.t. some TR problems. Can someone out there offer observations on the 902 series with TR problems (equivalent).
What goes round...comes round.
------------------
Thermal runaway.
Eden: Guess who's been thru beefers school then!! Brilliant contribution..if only it was so predictable in real life!!
SPS: How on earth can you 'practice' real TR failures in the hover. Do you have a disconnect coupling in the drive train??
Thing to remember, in addition to the effects of surviving the initial bang....if the TR decides to take off, you're left with a major C of G problem [as per the story of the vietnam helo pilot who got his tail blown off with a SAM 7].
Different a/c types have their pros and cons too. Fenestrons offer advantages w.r.t. some TR problems. Can someone out there offer observations on the 902 series with TR problems (equivalent).
What goes round...comes round.
------------------
Thermal runaway.
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Shytorque,
Glad you pointed that one out. We use to use a B222 on marine pilot transfers and the norm was to lose the door on short final due to the floats. We now use a BK117, which seems to be a little more forgiving when it comes to the doors. Although the rear sliding doors do come into contact with the floats whilst jettisoning, it dosn't stop the pax from getting out.
On the single engine stuff, I am under the impression that you will most likely need a small amount of power during the auto and flare if you have a 'basic' drive failure. All got to do with drag etc from the transmission.
One other thing to nut over. Does the tail rotor go into auto itself if you boot in right pedal during a drive failure (American heli's)? Maybe it could give an additional, albeit small, amount of stability to an unstable situation. (could you overspeed a T/R)
Food for thought if nothing else.
Glad you pointed that one out. We use to use a B222 on marine pilot transfers and the norm was to lose the door on short final due to the floats. We now use a BK117, which seems to be a little more forgiving when it comes to the doors. Although the rear sliding doors do come into contact with the floats whilst jettisoning, it dosn't stop the pax from getting out.
On the single engine stuff, I am under the impression that you will most likely need a small amount of power during the auto and flare if you have a 'basic' drive failure. All got to do with drag etc from the transmission.
One other thing to nut over. Does the tail rotor go into auto itself if you boot in right pedal during a drive failure (American heli's)? Maybe it could give an additional, albeit small, amount of stability to an unstable situation. (could you overspeed a T/R)
Food for thought if nothing else.
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As a low timer, my only experience of TR problems is my CPL instructor's boot on the pedals (I never practiced or had this demonstrated at PPL). All I can say is that I would NOT like to do it for real! Things were stressful enough and wild enough close to the ground in the practice situation.
Eden's post is great, and I'm printing it off for future reference. One thing, though, I was briefed to aim for a runway if poss, as the concrete is somewhat more forgiving if the touchdown is made pointing more sideways than might otherwise be prudent. Having practiced to grass, I was hoping concrete would be slightly easier.
I've decided, reading this thread, to grab my old instructor and have him jam his boot on the pedal again and see how I get on.
Eden's post is great, and I'm printing it off for future reference. One thing, though, I was briefed to aim for a runway if poss, as the concrete is somewhat more forgiving if the touchdown is made pointing more sideways than might otherwise be prudent. Having practiced to grass, I was hoping concrete would be slightly easier.
I've decided, reading this thread, to grab my old instructor and have him jam his boot on the pedal again and see how I get on.
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Thomas Coupling -
I wrote 'The last time I renewed by Inst. rating in UK We did TRUE TR failure in the hover'
I used 'true' in preference to 'real' as I thought the latter unsuitable.
I can see your point, we can only simulate having no TR thrust but cannot disconnect the TR so we have to get as close as possible
by using full right pedal.
Isn't this actually a very accurate simulation though? The TR has to be capable of making thrust in both left and right directions, one of the main reasons for that requirement being that friction effect in autorotation (nose yaws left) must be balanced by TR thrust in the opposite direction to powered flight.
(The neutral position for TR thrust on the ground in an R22 is with the right pedal a good deal forward, not with the pedals level with each other. The TR is rigged to give more control range to the left for powered flight)
Somewhere inbetween full left pedal and full right pedal there is a completely neutral TR pitch setting which is the same as having no TR thrust at all. If you use full right pedal you are actually PAST the zero TR thrust to the right value and into the (narrower)thrust to the left range. That must be ADDING to the speed of right yaw that would result from having no TR thrust due to a true (true making the distinction between a complete loss of TR thrust and other problems such as control failure or jamming) TR failure.
So it seems to me that full right pedal in the hover is a very realistic way of simulating a complete loss of TR thrust in the hover. It gives a greater yaw rate than a complete loss of TR thrust would do in the same profile.
I agree that it would be good to hear from any low hours pilots reading on the sideline, I think that the forum would benefit if more of that were to happen.
Moving on, The control failure in the hover (UK) that I saw was caused by a TR swashplate bearing siezure. The swashplate then wanted to rotate with the TR driveshaft which broke the horn control connection and left the TR in a fixed pitch state. The Instructor got it down fine although it was yawing slowly, I cant remember in which direction but guess that it must have been to the left as the lever was lowered to land.
It is important to note that this was a machine left outside in all UK weathers and had done around 1200 hrs. The bearing is lifed for 2000 hrs but leaving it to be ravaged by those conditions can do it no good at all.
I wrote 'The last time I renewed by Inst. rating in UK We did TRUE TR failure in the hover'
I used 'true' in preference to 'real' as I thought the latter unsuitable.
I can see your point, we can only simulate having no TR thrust but cannot disconnect the TR so we have to get as close as possible
by using full right pedal.
Isn't this actually a very accurate simulation though? The TR has to be capable of making thrust in both left and right directions, one of the main reasons for that requirement being that friction effect in autorotation (nose yaws left) must be balanced by TR thrust in the opposite direction to powered flight.
(The neutral position for TR thrust on the ground in an R22 is with the right pedal a good deal forward, not with the pedals level with each other. The TR is rigged to give more control range to the left for powered flight)
Somewhere inbetween full left pedal and full right pedal there is a completely neutral TR pitch setting which is the same as having no TR thrust at all. If you use full right pedal you are actually PAST the zero TR thrust to the right value and into the (narrower)thrust to the left range. That must be ADDING to the speed of right yaw that would result from having no TR thrust due to a true (true making the distinction between a complete loss of TR thrust and other problems such as control failure or jamming) TR failure.
So it seems to me that full right pedal in the hover is a very realistic way of simulating a complete loss of TR thrust in the hover. It gives a greater yaw rate than a complete loss of TR thrust would do in the same profile.
I agree that it would be good to hear from any low hours pilots reading on the sideline, I think that the forum would benefit if more of that were to happen.
Moving on, The control failure in the hover (UK) that I saw was caused by a TR swashplate bearing siezure. The swashplate then wanted to rotate with the TR driveshaft which broke the horn control connection and left the TR in a fixed pitch state. The Instructor got it down fine although it was yawing slowly, I cant remember in which direction but guess that it must have been to the left as the lever was lowered to land.
It is important to note that this was a machine left outside in all UK weathers and had done around 1200 hrs. The bearing is lifed for 2000 hrs but leaving it to be ravaged by those conditions can do it no good at all.
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To Offshore
Great Subject, lots of experienced pilots "experiences" for novices to learn something from, however putting this into practice real time for us novices is another matter.
To Thomas Coupling
I think I fit in to the novice category very well (PPLH gained 10 months and some 200 hours ago in the UK)So here goes on my experiences/thoughts on the prospect of a TR failure.
When doing my PPL H experience of Simulated TR failure was limited to approximately 10 minutes of demonstration by my instructor, at this point the following thoughts sprung to mind.
1. Sh**
2. I hope that never happens to me.
3. How on earth can you Practic TR failure in its various forms.
4. I now know enough to make me think that if it happened to me I had NO chance.
Luckily after gaining my PPL H (which after all is only a licence to learn) I had to go to the US to do a conversion course onto a NOTAR helicopter(more of that later) but during the course we covered TR (fan) failures in all their various forms Fan failure and or fixed left pedal in the hover being my particular favourite. These failures proved very realistic (I guess) and only required flying the heli with your instructor working the pedals (the factory test pilots who have actually had the failures for real)This then gave me the following thoughts.
1.The PPL H course in the UK should either not cover it at all(ignorance is bliss!)or do it properely(maybe this was just my instructors and not the course ?)
2.I still have a lot to learn.
3.OK while it was only simulated, I now feel more comfortable with TR failures.
4.I would react better to the situation.
5.If it does happen I won't just be waiting for the crash , I will be trying to do something about it when I crash !!!!!!
6.BUT no one told life/situations to follow what it says in the book!
To Eden
You mentined the NOTAR system in one of your posts, and the fact it may be better with a failure. In my experience if the fan fails its jsut like any loss of TR, except for maybe above 35 Knots IAS when the steerable verticals are in effect, but then if you have a fixed pedal scenario they make it even worse in certain cases. The drive to the fan can fail just the same as a TR, the big bonus is that the fan is less likely to strike anything to cause the failurein the first place! Wether in flight or in the hover.
To All Novices like Me
Remember this in your quest for flying knowledge:
"In the life that is helicopter flying we start off with 2 Bags, One bag of LUCK which is FULL, the other bag is for EXPERIENCE and is EMPTY, Make sure you FILL the bag of EXPERIENCE BEFORE your bag of LUCK runs OUT"
Cant remember who told me this/wrote it but they are very wise.
Regards
hoverbover
Great Subject, lots of experienced pilots "experiences" for novices to learn something from, however putting this into practice real time for us novices is another matter.
To Thomas Coupling
I think I fit in to the novice category very well (PPLH gained 10 months and some 200 hours ago in the UK)So here goes on my experiences/thoughts on the prospect of a TR failure.
When doing my PPL H experience of Simulated TR failure was limited to approximately 10 minutes of demonstration by my instructor, at this point the following thoughts sprung to mind.
1. Sh**
2. I hope that never happens to me.
3. How on earth can you Practic TR failure in its various forms.
4. I now know enough to make me think that if it happened to me I had NO chance.
Luckily after gaining my PPL H (which after all is only a licence to learn) I had to go to the US to do a conversion course onto a NOTAR helicopter(more of that later) but during the course we covered TR (fan) failures in all their various forms Fan failure and or fixed left pedal in the hover being my particular favourite. These failures proved very realistic (I guess) and only required flying the heli with your instructor working the pedals (the factory test pilots who have actually had the failures for real)This then gave me the following thoughts.
1.The PPL H course in the UK should either not cover it at all(ignorance is bliss!)or do it properely(maybe this was just my instructors and not the course ?)
2.I still have a lot to learn.
3.OK while it was only simulated, I now feel more comfortable with TR failures.
4.I would react better to the situation.
5.If it does happen I won't just be waiting for the crash , I will be trying to do something about it when I crash !!!!!!
6.BUT no one told life/situations to follow what it says in the book!
To Eden
You mentined the NOTAR system in one of your posts, and the fact it may be better with a failure. In my experience if the fan fails its jsut like any loss of TR, except for maybe above 35 Knots IAS when the steerable verticals are in effect, but then if you have a fixed pedal scenario they make it even worse in certain cases. The drive to the fan can fail just the same as a TR, the big bonus is that the fan is less likely to strike anything to cause the failurein the first place! Wether in flight or in the hover.
To All Novices like Me
Remember this in your quest for flying knowledge:
"In the life that is helicopter flying we start off with 2 Bags, One bag of LUCK which is FULL, the other bag is for EXPERIENCE and is EMPTY, Make sure you FILL the bag of EXPERIENCE BEFORE your bag of LUCK runs OUT"
Cant remember who told me this/wrote it but they are very wise.
Regards
hoverbover
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I think the big thing to remember here is that with the exception of a total drive failure or actual loss of complete T/R assembly, the one thing you will have lots of, is time.
Don't be in a mad panic to get down. Take your time and experiment with power and airspeed combinations that will give the best profile for landing.
On wheel equipped A/C, you will be able to run the A/C on at a considerably higher than published speed i.e. S76 60-70 Kts! Skid equipped A/C, if recovered at a runway, can also run on at a fairly higher than normal speed (obviously not great for the skids but at least you get down in one piece).
Someone asked about the T/R being 'Auto'd'. The SH/UH60 has the tail rotor mounted on an angle (I forget the exact amount). If a total loss of T/R drive is experienced it is recommended that the aircraft be banked 20-30 degrees (I think to the left). This causes the T/R to autorotate to some extent returning, I believe about 50% tailrotor control.
Well keep it coming as I do believe this may turn into a very educational topic for all.
Cheers, OffshoreIgor
Don't be in a mad panic to get down. Take your time and experiment with power and airspeed combinations that will give the best profile for landing.
On wheel equipped A/C, you will be able to run the A/C on at a considerably higher than published speed i.e. S76 60-70 Kts! Skid equipped A/C, if recovered at a runway, can also run on at a fairly higher than normal speed (obviously not great for the skids but at least you get down in one piece).
Someone asked about the T/R being 'Auto'd'. The SH/UH60 has the tail rotor mounted on an angle (I forget the exact amount). If a total loss of T/R drive is experienced it is recommended that the aircraft be banked 20-30 degrees (I think to the left). This causes the T/R to autorotate to some extent returning, I believe about 50% tailrotor control.
Well keep it coming as I do believe this may turn into a very educational topic for all.
Cheers, OffshoreIgor
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hoverbover:
Thanks for that info' I was kind of alluding to the fact that I wasn't really aware or sure of what happened with these beasts, having never flown one. I felt that they might present a different set of problems and was kind of hoping that someone would jump on my ignorance a sort me out - so I am grateful for your advice.
Out of interest: for those who may have had a TR CONTROL problem (as opposed t failure) the techiques I describe work - having had a cockpit floor full of Seagull and derision wedged firmly amongst the pedals of a Gazelle during a low level sortie. Luckily -the problem it gave me enabled me to return for a slow speed running landing which was all very benign .....the greatest shock is a facefull of feathers, a facewash of Seagull blood but the remains made for good burgers at lunch!
Thanks for that info' I was kind of alluding to the fact that I wasn't really aware or sure of what happened with these beasts, having never flown one. I felt that they might present a different set of problems and was kind of hoping that someone would jump on my ignorance a sort me out - so I am grateful for your advice.
Out of interest: for those who may have had a TR CONTROL problem (as opposed t failure) the techiques I describe work - having had a cockpit floor full of Seagull and derision wedged firmly amongst the pedals of a Gazelle during a low level sortie. Luckily -the problem it gave me enabled me to return for a slow speed running landing which was all very benign .....the greatest shock is a facefull of feathers, a facewash of Seagull blood but the remains made for good burgers at lunch!