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Helicopter down outside Leicester City Football Club

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Helicopter down outside Leicester City Football Club

Old 30th Oct 2022, 20:31
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I suggest we stay on topic….this accident was caused by mechanical failure, rather than a captaincy issue.
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Old 14th Nov 2022, 14:09
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Originally Posted by ShyTorque
I suggest we stay on topic….this accident was caused by mechanical failure, rather than a captaincy issue.
Was the accident caused by mechanical failure or the pilots inability to cope with or action training to cope with the mechanical failure? I have no idea the recurrent training that UK licences go through but as a long retired FAA ATPL holder the failure of the tail rotor assembly, or all manner of associated failures was beaten to death in annual proficiency checks in North America. I'm at a loss as to why so many posters on here say in the UK you never train for this, I'd like to hear why.
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Old 14th Nov 2022, 14:17
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It went to sub-minimum pitch which is below the lowest possible power setting conceived by the manufacturer. So even if you executed as much training you like it was beyond saving from a hover. And we do train for the scenario - a lot.
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Old 14th Nov 2022, 14:49
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Originally Posted by gipsymagpie
It went to sub-minimum pitch which is below the lowest possible power setting conceived by the manufacturer. So even if you executed as much training you like it was beyond saving from a hover. And we do train for the scenario - a lot.
I think it was at 430 ft? You couldn't get the collective down and the power off and get some forward airspeed and airflow over the fuselage? What did you practice when you train for that scenario since I'm failing to see how it was unrecoverable.
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Old 14th Nov 2022, 15:05
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mmm. yeah, good luck with that, especially at night

I imagine most pilots with a tail rotor failure in a hover, at height, would not be able to deal with it. after two rotations it's game over


Originally Posted by Pickuptruck
I think it was at 430 ft? You couldn't get the collective down and the power off and get some forward airspeed and airflow over the fuselage? What did you practice when you train for that scenario since I'm failing to see how it was unrecoverable.
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Old 14th Nov 2022, 15:44
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The tail rotor wasn't failed, it was sub minimum pitch. So even if you snapped the collective down it would continue to spin left (the tail rotor is driving the thing left rather than the yaw being a function of the torque reaction). So even with the lever full down and cyclic stuffed forward, you wouldn't gain much airspeed as you're yawing hard left despite the lever being down.

Of note the minimum position of the tail rotor is determined in design by some flight condition where left yaw is required at very low power. On several types I've operated this was defined (and tested during a maintenance test flight) as the ability to yaw left at a reasonable rate (cannot recall the exact condition) whilst in a zero speed autorotation (great fun to do that flight test). In this incident the yaw setting was even less than this due to the mode of failure. That's a lot of yaw and even by day at several thousand feet I would suggest you would struggle. I would expect the required recovery action would be to lower the lever, pitch hard nose down and roll - I think roll to oppose the yaw (and also further reducing power/torque requirements) so you could accelerate but rolling into the yaw might offer the chance to align the fuselage with the airflow. Pure speculation as you could never test it.

Those guys had a awful roll of the dice that night.
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Old 14th Nov 2022, 16:22
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You couldn't get the collective down and the power off and get some forward airspeed and airflow over the fuselage? What did you practice when you train for that scenario since I'm failing to see how it was unrecoverable.
Because the scenario they had is not the one in your head. I think their bad luck was compounded by landing on a small wall which ruptured the fuel tanks. It may well have been survivable up until that point.
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Old 14th Nov 2022, 17:48
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Originally Posted by Pickuptruck
Was the accident caused by mechanical failure or the pilots inability to cope with or action training to cope with the mechanical failure? I have no idea the recurrent training that UK licences go through but as a long retired FAA ATPL holder the failure of the tail rotor assembly, or all manner of associated failures was beaten to death in annual proficiency checks in North America. I'm at a loss as to why so many posters on here say in the UK you never train for this, I'd like to hear why.
I thought this had already been discussed at some length earlier on.

A tail rotor drive failure, believe it or not, is relatively straightforward to deal with, albeit needing altitude and time once the engines are shut down.

A tail rotor control failure is most definitely not the same kettle of fish and is likely to be far more difficult to deal with, unless the tail rotor blade pitch remains at a setting close to neutral. A control runaway to maximum positive pitch may require maximum collective pitch to slow the yaw (and then what, how do you get the aircraft down under control?).

A tail rotor which runs away to minimum pitch will very likely have enough authority to yaw the aircraft at a high rate even after the engines are shut down. If you think about this, a helicopter in full auto rotation needs enough tail rotor authority to enable full yaw control in both directions, so there is more negative pitch designed in than some might realise. For example, one aircraft I used to instruct (RAF Puma) had something like 35 degrees of positive pitch and 17 degrees of negative pitch. We regularly used a full motion simulator to practice tail rotor malfunctions of all types and it showed that runaways to negative pitch were usually impossible to deal with, especially if the failure occurred at high engine power settings, as in the Leicester accident being discussed here. The tail rotor control system failed and drove the tail rotor blades to full negative pitch. As recently stated by others here, shutting the engines down immediately the failure occurred would nothave stopped the yawing.

A helicopter yawing out of control in this instance is unlikely to remain stable in the roll and pitch attitudes and may go completely out of control despite the best crew in the world sitting in the cockpit.
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Old 14th Nov 2022, 21:46
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Originally Posted by Pickuptruck
I think it was at 430 ft? You couldn't get the collective down and the power off and get some forward airspeed and airflow over the fuselage? What did you practice when you train for that scenario since I'm failing to see how it was unrecoverable.
Seems likely that you are not a helicopter pilot. Or if you are, not one I’d like to fly with.
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Old 15th Nov 2022, 01:41
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Originally Posted by ShyTorque
I thought this had already been discussed at some length earlier on.

A tail rotor drive failure, believe it or not, is relatively straightforward to deal with, albeit needing altitude and time once the engines are shut down.

A tail rotor control failure is most definitely not the same kettle of fish and is likely to be far more difficult to deal with, unless the tail rotor blade pitch remains at a setting close to neutral. A control runaway to maximum positive pitch may require maximum collective pitch to slow the yaw (and then what, how do you get the aircraft down under control?).

A tail rotor which runs away to minimum pitch will very likely have enough authority to yaw the aircraft at a high rate even after the engines are shut down. If you think about this, a helicopter in full auto rotation needs enough tail rotor authority to enable full yaw control in both directions, so there is more negative pitch designed in than some might realise. For example, one aircraft I used to instruct (RAF Puma) had something like 35 degrees of positive pitch and 17 degrees of negative pitch. We regularly used a full motion simulator to practice tail rotor malfunctions of all types and it showed that runaways to negative pitch were usually impossible to deal with, especially if the failure occurred at high engine power settings, as in the Leicester accident being discussed here. The tail rotor control system failed and drove the tail rotor blades to full negative pitch. As recently stated by others here, shutting the engines down immediately the failure occurred would nothave stopped the yawing.

A helicopter yawing out of control in this instance is unlikely to remain stable in the roll and pitch attitudes and may go completely out of control despite the best crew in the world sitting in the cockpit.
Thank you for the explanation.
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Old 15th Nov 2022, 12:19
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Originally Posted by Pickuptruck
Thank you for the explanation.
Out of interest, how exactly did you train in the machine for TR failure? What ever you did, I doubt it was an accurate reflection of reality.
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Old 15th Nov 2022, 12:33
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Originally Posted by 212man
Out of interest, how exactly did you train in the machine for TR failure? What ever you did, I doubt it was an accurate reflection of reality.
It was a few decades ago and you're probably right, pedals jammed full left or full right or locked centre. Check airman was retired USMC.
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Old 15th Nov 2022, 20:33
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Originally Posted by Pickuptruck
It was a few decades ago and you're probably right, pedals jammed full left or full right or locked centre. Check airman was retired USMC.
Yes, done it that way myself.
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Old 15th Nov 2022, 22:21
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Originally Posted by MightyGem
Yes, done it that way myself.
So did the RAF. From what I experienced, for many years too little thought was put into the subject. When we first began using a capable simulator for tail rotor control malfunctions, rather than the “more simple” tail rotor drive failures, the learning curve was steep. It was a startling revelation.
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Old 16th Nov 2022, 20:19
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Originally Posted by ShyTorque
So did the RAF. From what I experienced, for many years too little thought was put into the subject. When we first began using a capable simulator for tail rotor control malfunctions, rather than the “more simple” tail rotor drive failures, the learning curve was steep. It was a startling revelation.
Yes, in the sim you could save a Lynx from a TRDS failure in the cruise enough to choose when to enter into autorotation. Whether it would work in real life??
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Old 16th Nov 2022, 22:08
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Originally Posted by MightyGem
Yes, in the sim you could save a Lynx from a TRDS failure in the cruise enough to choose when to enter into autorotation. Whether it would work in real life??
That would depend on how it had been programmed, of course.

The important lesson to learn is that there are different types of TR malfunction apart from driveshaft failure and they need some thought, preferably before they occur in the real aircraft - Hence the value of a simulator.


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Old 16th Nov 2022, 22:21
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There are more ways to control yaw thrust than by moving the pedals....far too few helicopter pilots fully understand that.

Bell designs with the Throttle(s) on the Collective make it fairly easy.... but aircraft with conventional ECL's can also be made to work in a similar manner.

But....in the accident under discussion....there was a very unusual mechanical failure that certainly made a successful recovery very unlikely under the circumstances the Crew were confronted with.
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Old 17th Nov 2022, 19:43
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Originally Posted by SASless
There are more ways to control yaw thrust than by moving the pedals....far too few helicopter pilots fully understand that.
Could you expand a little on that for this non-rotary-winged pilot? I (think) I can understand the basics whereby pulling pitch increases the yaw tendency, but that's the extent of my understanding and I'd like to learn a bit more more.
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Old 17th Nov 2022, 20:11
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Think of the tail rotor much like a constant speed Prop on an airplane....the amount of thrust produced can be varied by changing the pitch of the Prop....or if you leave the Prop Pitch constant....you can alter the thrust produced by changing the RPM.

Assuming the Tail Rotor is turning....and it is a fixed control problem causing the issue....one can vary the RPM by means of the Engine(s) throttle(s).

Collective setting or movement can also affect yaw in that situation by increasing or decreasing the amount of Torque of the Main Rotor produces.

Adding Collective produces more an increase in torque.....and the opposite when Collective is reduced.

Page 11-16 provides the FAA discussion of Tail Rotor Malfunctions.

https://www.faa.gov/sites/faa.gov/fi...k/hfh_ch11.pdf
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Old 17th Nov 2022, 21:03
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Originally Posted by SASless
Think of the tail rotor much like a constant speed Prop on an airplane....the amount of thrust produced can be varied by changing the pitch of the Prop....or if you leave the Prop Pitch constant....you can alter the thrust produced by changing the RPM.

Assuming the Tail Rotor is turning....and it is a fixed control problem causing the issue....one can vary the RPM by means of the Engine(s) throttle(s).

Collective setting or movement can also affect yaw in that situation by increasing or decreasing the amount of Torque of the Main Rotor produces.

Adding Collective produces more an increase in torque.....and the opposite when Collective is reduced.

Page 11-16 provides the FAA discussion of Tail Rotor Malfunctions.

https://www.faa.gov/sites/faa.gov/fi...k/hfh_ch11.pdf
Nice description. Also it’s worth adding that the thrust is following a ‘square law’ with the rpm. So small rpm variations have a big thrust change.
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