Helicopter down outside Leicester City Football Club
Avoid imitations
SAS,
That paper contains useful information on tail rotor drive failure and “stuck pedals” but it does not cover the very unusual situation suffered by the Leicester crew.
(I can’t imagine a situation where any helicopter in normal operational flight would need full negative tail rotor pitch).
During a normal Class A rearwards climb, such as this was, the pilot would have been applying a large amount of positive tail rotor pitch.
The aircraft mechanical controls failure suddenly gave him the maximum possible opposite tail rotor input. As I said before, I doubt very much that any pilot would have been able to recover from that situation. I’ve seen it in a simulator many times, both as a handling pilot and watching (and trying to assist and train from the instructor point of view).
This was far more severe than stuck pedals or even total loss of tail rotor power through drive shaft failure and even more so because the aircraft was in a low IAS climb, in accordance with that type of departure. The only hope would be to rapidly achieve full auto rotation and even if that was achievable (it probably wasn’t because of the rapid onset of a high yaw rate) the pilot would still be trying to deal with uncontrollable yaw at very low level - and in the dark!
For those pilots not familiar with helicopters, the closest analogy I can think of in fixed wing terms is for an aeroplane with a high torque propellor engine to be in a minimum IAS climb. The pilot is keeping the aircraft straight using ant-torque rudder. A mechanical failure causes sudden full opposite rudder to be applied, causing a high rotational spin to develop with full pro spin rudder jammed on.
That paper contains useful information on tail rotor drive failure and “stuck pedals” but it does not cover the very unusual situation suffered by the Leicester crew.
(I can’t imagine a situation where any helicopter in normal operational flight would need full negative tail rotor pitch).
During a normal Class A rearwards climb, such as this was, the pilot would have been applying a large amount of positive tail rotor pitch.
The aircraft mechanical controls failure suddenly gave him the maximum possible opposite tail rotor input. As I said before, I doubt very much that any pilot would have been able to recover from that situation. I’ve seen it in a simulator many times, both as a handling pilot and watching (and trying to assist and train from the instructor point of view).
This was far more severe than stuck pedals or even total loss of tail rotor power through drive shaft failure and even more so because the aircraft was in a low IAS climb, in accordance with that type of departure. The only hope would be to rapidly achieve full auto rotation and even if that was achievable (it probably wasn’t because of the rapid onset of a high yaw rate) the pilot would still be trying to deal with uncontrollable yaw at very low level - and in the dark!
For those pilots not familiar with helicopters, the closest analogy I can think of in fixed wing terms is for an aeroplane with a high torque propellor engine to be in a minimum IAS climb. The pilot is keeping the aircraft straight using ant-torque rudder. A mechanical failure causes sudden full opposite rudder to be applied, causing a high rotational spin to develop with full pro spin rudder jammed on.
Shy....also remember Simulators "simulate" not "replicate" actual aircraft flight characteristics.
Computers can do only so much despite being very useful bits of kit
We havre to remind folks not to hang their hats on a direct transfer from the real to the surreal in those pretty shiny boxes that oft times reek of someone's spilled lunch.
Plenty of very experienced Aviators have gotten Sim Sick who have never been Air Sick in their careers.
My. post was to offer an analogy that a fixed wing only pilot might be able to use to better understand the basic concepts.
Computers can do only so much despite being very useful bits of kit
We havre to remind folks not to hang their hats on a direct transfer from the real to the surreal in those pretty shiny boxes that oft times reek of someone's spilled lunch.
Plenty of very experienced Aviators have gotten Sim Sick who have never been Air Sick in their careers.
My. post was to offer an analogy that a fixed wing only pilot might be able to use to better understand the basic concepts.
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
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
Avoid imitations
Originally Posted by SASless
Shy....also remember Simulators "simulate" not "replicate" actual aircraft flight characteristics
There is no way that a manufacturer could obtain fully representative aerodynamic data for all stages of a helicopter going out of control and it’s subsequent flight path…...they would soon run out of test pilots and aircraft. I was lucky enough to be able to work alongside the chap who programmed the sim we worked on and he was always keen to remind us of that fact. In turn, we used to emphasise this to all the RAF pilots we trained. We used the simulator as a sophisticated procedures trainer, not an actual aircraft.
I’ve mentioned before that one of our crews subsequently suffered a tail rotor control failure over the sea and successfully ditched the aircraft in the water with no injuries. The pilot stated afterwards that his simulator training prevented him from doing what he said would previously have been his prior instinct of merely chopping the throttles and entering autorotation. Doing that would have made matters worse in his case, because the tail control mechanism had failed with some positive pitch. Instead he made a gentle yawing descent onto the surface. Despite not having floats the aircraft was subsequently recovered almost intact.
But unfortunately the Leicester accident was a far less benign failure.
Plenty of very experienced Aviators have gotten Sim Sick who have never been Air Sick in their careers.
Avoid imitations
Megan, I noticed that pilots with a lot of hours on the actual aircraft often tended to suffer the most. I put this down to a discrepancy between the “seat of the pants” learning already in memory and what the eyes were seeing. This is obviously a limitation of the motion of a simulator bolted to the floor, partly because the motion gently resets between inputs.
Avoid imitations
PCD, Quite a few did. Including one of my colleagues there who later went on to manage the project! 
In my time teaching in the Sim....from the early 76 Simulator at American Airlines Training....to the very much improved Sims for the 212/412 at the FSI facility at the Bell factory.....I only experienced Sim sickness one time....and have never had any problem with motion sickness ever even in very rough water on boats and ships.
The lag between the visual and the Sim is one factor but the most important cause is the way the Sim System works to generate felt forces due to pitch and roll.
In the real aircraft the airframe moves relative to the horizon and once in a stabilized turn or change in pitch attitude that results in a constant relative angle....no other "motion" is felt.
In the Sim....once the "Box" moves per the flight control input....say for example a thirty degree bank.....the "Box" leans over.....and then despite the instruments showing that angle of bank....the Box begins to re-center so it can have a full range of motion available.
Our well tuned hind quarters feel the forces of gravity....and our eyes are seeing something else and the confusion caused by those inputs is what gets us.
The usual victim is the guy not doing much because if you are flying or running the Sim at the Control Panel....each are "busy" and are not free to focus upon the odd sensations.
The lag between the visual and the Sim is one factor but the most important cause is the way the Sim System works to generate felt forces due to pitch and roll.
In the real aircraft the airframe moves relative to the horizon and once in a stabilized turn or change in pitch attitude that results in a constant relative angle....no other "motion" is felt.
In the Sim....once the "Box" moves per the flight control input....say for example a thirty degree bank.....the "Box" leans over.....and then despite the instruments showing that angle of bank....the Box begins to re-center so it can have a full range of motion available.
Our well tuned hind quarters feel the forces of gravity....and our eyes are seeing something else and the confusion caused by those inputs is what gets us.
The usual victim is the guy not doing much because if you are flying or running the Sim at the Control Panel....each are "busy" and are not free to focus upon the odd sensations.
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I was asked if the Pilot had shut down or reduced engine power by means of the ECL's or throttles....and could not respond to that question.
Does anyone know of a reference to that in any official report or discussion?
Does anyone know of a reference to that in any official report or discussion?
