AS350 Astar/Squirrel
Gatvol
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The ship was taking off with an external load on a 50ft rope when suddenly in 100ft it began to spin to the left
After you get those, Im sure you will see what makes the world go around............
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Most LTE's are due to rotor rpm drooping when too much power is commanded. Lowering the rpm reduces the available tail rotor authority, and is really not LTE, but rather over-pitching, a good British term. What was the power/rotor rpm during the incident?
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thank you nick, thank you,
overpitching at last, instead of more of this crap about lte.
obviously if you run out of main rotor rpm you will lose tail rotor effectiveness. if the wind changes speed you get loss of tailrotor effectivness.
the chance of weather cocking with a heavy load load at altitude is to be totally expected and not a consequence of lte but a case of no more power available, something has to give.
i know why pilots like to think lte was to blame, it's because it is a good excuse for bad handling or inattentiveness.
better than telling the boss that you overpitched his machine and bent it.
"it had nothing to do with me boss", "it was that bloody lte phenomena", or "I could still pull pitch so i must of had more power left, then it started spinning all by itself".
thanks again nick for the reality check.
overpitching at last, instead of more of this crap about lte.
obviously if you run out of main rotor rpm you will lose tail rotor effectiveness. if the wind changes speed you get loss of tailrotor effectivness.
the chance of weather cocking with a heavy load load at altitude is to be totally expected and not a consequence of lte but a case of no more power available, something has to give.
i know why pilots like to think lte was to blame, it's because it is a good excuse for bad handling or inattentiveness.
better than telling the boss that you overpitched his machine and bent it.
"it had nothing to do with me boss", "it was that bloody lte phenomena", or "I could still pull pitch so i must of had more power left, then it started spinning all by itself".
thanks again nick for the reality check.
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Imabell,
or perpahs direction.
Ok explain to me your deffenition of LTE.
When you have a light varaible wind, you position into the current/ most prevenlant wind direction, then wind shift slightly and you are at a high power setting and you "weathercock" or have an uncommanded yaw. Recoverable or not, how is that not a symptom or byproduct of LTE?
So all these 206 accidents at altitude with uncommanded yaw on short final to spots are all over pitching? not lte? Tailrotor authority has nothing to do with it?
rb
if the wind changes speed you get loss of tailrotor effectivness.
Ok explain to me your deffenition of LTE.
When you have a light varaible wind, you position into the current/ most prevenlant wind direction, then wind shift slightly and you are at a high power setting and you "weathercock" or have an uncommanded yaw. Recoverable or not, how is that not a symptom or byproduct of LTE?
So all these 206 accidents at altitude with uncommanded yaw on short final to spots are all over pitching? not lte? Tailrotor authority has nothing to do with it?
rb
Terminology: the bane of understanding!
Rotorboy, I see your points, but I think you are mixing the terminology between LTE, Authority and perhaps not understanding imabell's oevrpitched call. So we are all singing from the same sheet of music, I suggest the following terminology cut and pasted from another thread:
Loss of tail rotor control: You are not able to control the tail rotor pitch mechanism.
Loss of tail rotor thrust: Little spinning thing at the back stops spinning or falls off.
Loss of tail rotor effectiveness (LTE): "Newly" discovered and named in the 80's after many (in particular OH-58/B206) accidents. Although somewhat awkwardly named (as the tail rotor is still effectively working and must be providing thrust) LTE refers to what is thought to be an ingestion of main or tail rotor vorticey through the tail rotor which causes an onset of yaw in the direction induced by torque that cannot be overcome by the application of full "power pedal". The yaw rotation can build up quickly enough to fool most pilots into believing they have experienced a loss of tail rotor thrust. The concept has come under fire lately because of the early thoughts that the tail rotor enters vortex ring state being a little hard to prove. Oh - and then there is fenestron stall that possibly fits into this category too, although strongly denied as a possibility by the manufacturer whilst allegedly being strongly experienced by the pilots!
Loss of Tail Rotor Authority (LTA): Also a new term to make the old Huey war story of "..and then I ran out of left pedal and..." sound a little more sophisticated and technical. In this situation, the tail rotor does not produce enough thrust to counteract the torque/crosswind combination you require, your power pedal hits the stop, and around you go - though often quite gently when compared to LTE or loss of thrust. A lot of aircraft are susceptible to this, but the UH-1D/H Huey is famous for it - and many people have had the earth come up and smite them as a result.
This is somewhat semantics, but the reason I used the term Loss of Tail Rotor Authority instead of “Over pitched” is that it confuses the situation a bit. Over pitched infers that the blade pitch angle is too excessive either for the engine power to overcome the induced drag, or that the blade may be in some sort of stall condition. Most commonly, over pitching refers to the main rotor case (as Nick says below) causing a RRPM droop and therefore LTA, or it could mean a T/R blade overpitch causing LTA. Either way, both manifest in a LTA situation - not an LTE.
But not all LTA is caused by over pitching. LTA also covers the other conditions where niether the M/R or T/R blade is over pitched but the T/R still cannot produce enough thrust to counter act the yaw. IE the T/R blade pitch angle is at it's max, but the resultant thrust is insufficient to overcome the yaw conditions caused by power, DA, adverse wind, pilot handling, etc.
So in green thumb's case, I don’t believe that the tail rotor or main rotor has “over pitched”, although as imabell points out, this common term has been clouded by the LTE hysteria, and somewhat forgotten - and with the forgotten term comes a forgotten condition and a forgotten recovery technique - and I share imabell's concern with this. Fly a UH-1H and you will be forced to remember.
In the AS 350 case, though you have yet to provide weight and DA details, I think an LTA case can be made: the T/R was unable to provide enough yaw authority for the power/DA/wind combination. Given that it was an AS 350, it is unlikely that the T/R blade was over pitched/stalled, and unlikely to be a main rotor droop – though the term over pitched certainly describes the aircraft reaction accurately, and the recovery actions are the same. (Unlikely does not mean impossible!)
edited to include corrections by AOTW!
Rotorboy, I see your points, but I think you are mixing the terminology between LTE, Authority and perhaps not understanding imabell's oevrpitched call. So we are all singing from the same sheet of music, I suggest the following terminology cut and pasted from another thread:
Loss of tail rotor control: You are not able to control the tail rotor pitch mechanism.
Loss of tail rotor thrust: Little spinning thing at the back stops spinning or falls off.
Loss of tail rotor effectiveness (LTE): "Newly" discovered and named in the 80's after many (in particular OH-58/B206) accidents. Although somewhat awkwardly named (as the tail rotor is still effectively working and must be providing thrust) LTE refers to what is thought to be an ingestion of main or tail rotor vorticey through the tail rotor which causes an onset of yaw in the direction induced by torque that cannot be overcome by the application of full "power pedal". The yaw rotation can build up quickly enough to fool most pilots into believing they have experienced a loss of tail rotor thrust. The concept has come under fire lately because of the early thoughts that the tail rotor enters vortex ring state being a little hard to prove. Oh - and then there is fenestron stall that possibly fits into this category too, although strongly denied as a possibility by the manufacturer whilst allegedly being strongly experienced by the pilots!
Loss of Tail Rotor Authority (LTA): Also a new term to make the old Huey war story of "..and then I ran out of left pedal and..." sound a little more sophisticated and technical. In this situation, the tail rotor does not produce enough thrust to counteract the torque/crosswind combination you require, your power pedal hits the stop, and around you go - though often quite gently when compared to LTE or loss of thrust. A lot of aircraft are susceptible to this, but the UH-1D/H Huey is famous for it - and many people have had the earth come up and smite them as a result.
This is somewhat semantics, but the reason I used the term Loss of Tail Rotor Authority instead of “Over pitched” is that it confuses the situation a bit. Over pitched infers that the blade pitch angle is too excessive either for the engine power to overcome the induced drag, or that the blade may be in some sort of stall condition. Most commonly, over pitching refers to the main rotor case (as Nick says below) causing a RRPM droop and therefore LTA, or it could mean a T/R blade overpitch causing LTA. Either way, both manifest in a LTA situation - not an LTE.
But not all LTA is caused by over pitching. LTA also covers the other conditions where niether the M/R or T/R blade is over pitched but the T/R still cannot produce enough thrust to counter act the yaw. IE the T/R blade pitch angle is at it's max, but the resultant thrust is insufficient to overcome the yaw conditions caused by power, DA, adverse wind, pilot handling, etc.
So in green thumb's case, I don’t believe that the tail rotor or main rotor has “over pitched”, although as imabell points out, this common term has been clouded by the LTE hysteria, and somewhat forgotten - and with the forgotten term comes a forgotten condition and a forgotten recovery technique - and I share imabell's concern with this. Fly a UH-1H and you will be forced to remember.
In the AS 350 case, though you have yet to provide weight and DA details, I think an LTA case can be made: the T/R was unable to provide enough yaw authority for the power/DA/wind combination. Given that it was an AS 350, it is unlikely that the T/R blade was over pitched/stalled, and unlikely to be a main rotor droop – though the term over pitched certainly describes the aircraft reaction accurately, and the recovery actions are the same. (Unlikely does not mean impossible!)
edited to include corrections by AOTW!
Overpitching (as I understand the term anyway) is when you pull too much collective for your engine's available power to overcome the drag, so the rotor system slows down; it doesn't necessarily imply a stall (even though I guess you could say that bits of the blade are stalled all the time). The only way to recover would be to lower the collective.
What I'm getting at is that in an 'overpitched' situation you'd have drooping Nr and the associated loss of main and tail rotor thrust, not necessarily the case in these so-called LTE situations.
As you say, helmet fire, the 206 LTE situation as we have had it explained to us is a rapid onset yaw probably caused by vortex ingestion.
I think that tends to support the Huey 'running out of left pedal' case being different to that, because you can sit there in the hover with the pedal bouncing off the stops but not be scared of whipping around to the right at a great rate - it feels controllable, while not necessarily comfortable.
What I'm getting at is that in an 'overpitched' situation you'd have drooping Nr and the associated loss of main and tail rotor thrust, not necessarily the case in these so-called LTE situations.
As you say, helmet fire, the 206 LTE situation as we have had it explained to us is a rapid onset yaw probably caused by vortex ingestion.
I think that tends to support the Huey 'running out of left pedal' case being different to that, because you can sit there in the hover with the pedal bouncing off the stops but not be scared of whipping around to the right at a great rate - it feels controllable, while not necessarily comfortable.
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thanks again nick, "lte does not exist".
but its not a way to blame the pilot it's a way for the pilot to move the blame to the helicopter.
only ' thought' to happen to the bell 206.
and your right too arm out the window, when you demand more power than any helicopter engine (piston included) can supply you end up with full left pedal and no tail rotor authority, ergo loss of tail rotor effectiveness.
fly the aircraft properly and it won't happen.
but its not a way to blame the pilot it's a way for the pilot to move the blame to the helicopter.
only ' thought' to happen to the bell 206.
and your right too arm out the window, when you demand more power than any helicopter engine (piston included) can supply you end up with full left pedal and no tail rotor authority, ergo loss of tail rotor effectiveness.
fly the aircraft properly and it won't happen.
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Thanks for your answers. I will try to describe the accident better.
An AS 350 BA (converted from "B") hauling loads with a 50ft rope in 3000ft PA, OAT 20°C, light and variable wind. Take off weight seems to be round about 1950-2100kg. (the load is destroyed and it's not possible to determine the weight of the load exactly) The >5000h experienced pilot lifted the load without problems and began to climb and to accelerate when suddenly the ship turns to the left. The left spin accelerated and wasn't to stop, even not with lowering the collective or full right pedal the pilot later explained. The ship and the load turned around the heads of the ground crew some full 360's and chrashed 50m ahead into the ground. The pilot doesn't opened the hook and released the load because he afraid to hurt someone on the ground.
As i wrote before there are no indications of a technical malfunction. The experienced ground crew reported the tail rotor was turning all the time. I' m surprised because the whole thing seems to me to be a kind of loss of directional control. That's not easy to understand because i thought LTE is a problem of the 206 or 500 series. Of course a loss of directional control is also possible on a AS350, but i have never heard about such a problem on AS 350 and never experienced personally on this type of helicopter. But i believe the pilot is really experienced on this kind of work, doing such flights a lot of years and will not loose the a/c out of control on such a "simple" flight during accelerating. But we are all humans and nothing is impossible.
Good to say the pilot isn't to bad injured and we all hope he will made a good and fast recovery.
An AS 350 BA (converted from "B") hauling loads with a 50ft rope in 3000ft PA, OAT 20°C, light and variable wind. Take off weight seems to be round about 1950-2100kg. (the load is destroyed and it's not possible to determine the weight of the load exactly) The >5000h experienced pilot lifted the load without problems and began to climb and to accelerate when suddenly the ship turns to the left. The left spin accelerated and wasn't to stop, even not with lowering the collective or full right pedal the pilot later explained. The ship and the load turned around the heads of the ground crew some full 360's and chrashed 50m ahead into the ground. The pilot doesn't opened the hook and released the load because he afraid to hurt someone on the ground.
As i wrote before there are no indications of a technical malfunction. The experienced ground crew reported the tail rotor was turning all the time. I' m surprised because the whole thing seems to me to be a kind of loss of directional control. That's not easy to understand because i thought LTE is a problem of the 206 or 500 series. Of course a loss of directional control is also possible on a AS350, but i have never heard about such a problem on AS 350 and never experienced personally on this type of helicopter. But i believe the pilot is really experienced on this kind of work, doing such flights a lot of years and will not loose the a/c out of control on such a "simple" flight during accelerating. But we are all humans and nothing is impossible.
Good to say the pilot isn't to bad injured and we all hope he will made a good and fast recovery.
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Would it be better to explain the "overpitch vs LTE" in this fashion?
It takes a fixed amount of horsepower to keep a helicopter hovering. For any horsepower, as RRPM goes down, torque (as expressed about the rotor mast) goes up. This demands more thrust from the tail rotor to maintain heading.
At the same time, the tail rotor RPM drops, therefore demanding a greater AOA just to maintain thrust. So you have two factors demanding left pedal, and there's only so much left pedal...
However, for most helicopters, the tail rotor is able to effectively counter any torque the engine/main rotor can develop as long as you keep the RPM in the green (and under most flight conditions). So for most helicopters, "LTE" can only happen if you overpitch, and droop the RPM while pulling a lot of power.
A few helicopters (B206, H269A) can, with RRPM in the (normal) green, regularly produce more torque about the rotor mast than the tail rotor can counter. So even if you are doing nothing "wrong", at high power settings you can find yourself running out of left pedal because the tail rotor is incapable of sufficient thrust even when operating at full RPM.
It takes a fixed amount of horsepower to keep a helicopter hovering. For any horsepower, as RRPM goes down, torque (as expressed about the rotor mast) goes up. This demands more thrust from the tail rotor to maintain heading.
At the same time, the tail rotor RPM drops, therefore demanding a greater AOA just to maintain thrust. So you have two factors demanding left pedal, and there's only so much left pedal...
However, for most helicopters, the tail rotor is able to effectively counter any torque the engine/main rotor can develop as long as you keep the RPM in the green (and under most flight conditions). So for most helicopters, "LTE" can only happen if you overpitch, and droop the RPM while pulling a lot of power.
A few helicopters (B206, H269A) can, with RRPM in the (normal) green, regularly produce more torque about the rotor mast than the tail rotor can counter. So even if you are doing nothing "wrong", at high power settings you can find yourself running out of left pedal because the tail rotor is incapable of sufficient thrust even when operating at full RPM.
Thoroughly agree with Nick here about the procedure on how to baby the aircraft and blame yourself when it all goes wrong! It was the same on the Skycrane thread: LTE is thrown about with such misunderstanding that it has succesfully hidden a design flaw in a shroud of aerodynamic faux-legitimacy! (I think I shoud resume drinking after that phrase - sorry!).
What green thumb describes is most assuredly not LTE, but that is the only one we can rule out from the description thus far. Without more info, we can only rule out LTE, we are left with Loss of tail rotor thrust, Loss of tail rotor control and LTA. We have a high power demand, with adverse wind direction ?? at relatively high DA (approx 4560 ft - plus humidity?) More questions are still required: was there any rotor droop? If so, was this due to N1 limiting, or governor malfunction? If not, was the tail rotor being driven (or just windmilling? The tail rotor was spinning - but was it powered? Were the t/r control mechanisms functioning? Was it a hydraulic event? Sounds like he held the load and crashed the aircraft? Was he able to move the aircraft away from the ground people, but not the load? Did he have the cargo release system active?
And others will bring more to the table I am sure.
What green thumb describes is most assuredly not LTE, but that is the only one we can rule out from the description thus far. Without more info, we can only rule out LTE, we are left with Loss of tail rotor thrust, Loss of tail rotor control and LTA. We have a high power demand, with adverse wind direction ?? at relatively high DA (approx 4560 ft - plus humidity?) More questions are still required: was there any rotor droop? If so, was this due to N1 limiting, or governor malfunction? If not, was the tail rotor being driven (or just windmilling? The tail rotor was spinning - but was it powered? Were the t/r control mechanisms functioning? Was it a hydraulic event? Sounds like he held the load and crashed the aircraft? Was he able to move the aircraft away from the ground people, but not the load? Did he have the cargo release system active?
And others will bring more to the table I am sure.
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Hi Nick,
Yep, I'm just a poor ol' head CFI trying to thread the briar patch between reality and what's printed in the textbooks we still have to answer to come checkride time. Since it was OVC002 all day, I got to engage a couple of my instructors in a discussion of this very subject, trying to find the balance.
We decided that if you get the "uncommanded yaw", you have just that. a yaw. If you react promptly and correctly and stop the yaw, it was not LTE. If the yaw stops on its own, not LTE. However, if you respond promptly and correctly but cannot stop the yaw, you have LTE (this still keeps us safe with the FAA). If you don't respond promptly or correctly, then you goofed - and the result cannot be truely classified as uncommanded (even if the first bit was) - hey you had your chance, Tex.
So if Sammy Schweizer gets his tail pushed around by that 12G20 tailwind, but ends up facing the wind going "wha'happah?", not LTE.
Rebecca Robbie gets sideways on a steep approach but stomps the left pedal and stops things, not LTE.
Joey Jetbanger starts seeing the word go 'round while OGE and downwind, and full left pedal won't stop it, LTE.
I agree that it is not altogether appropriate to call low-RPM induced "unstoppable yaw" LTE, but at that point, it ends up the same - (even if you initially screwed up by drooping the RPM).
Yep, I'm just a poor ol' head CFI trying to thread the briar patch between reality and what's printed in the textbooks we still have to answer to come checkride time. Since it was OVC002 all day, I got to engage a couple of my instructors in a discussion of this very subject, trying to find the balance.
We decided that if you get the "uncommanded yaw", you have just that. a yaw. If you react promptly and correctly and stop the yaw, it was not LTE. If the yaw stops on its own, not LTE. However, if you respond promptly and correctly but cannot stop the yaw, you have LTE (this still keeps us safe with the FAA). If you don't respond promptly or correctly, then you goofed - and the result cannot be truely classified as uncommanded (even if the first bit was) - hey you had your chance, Tex.
So if Sammy Schweizer gets his tail pushed around by that 12G20 tailwind, but ends up facing the wind going "wha'happah?", not LTE.
Rebecca Robbie gets sideways on a steep approach but stomps the left pedal and stops things, not LTE.
Joey Jetbanger starts seeing the word go 'round while OGE and downwind, and full left pedal won't stop it, LTE.
I agree that it is not altogether appropriate to call low-RPM induced "unstoppable yaw" LTE, but at that point, it ends up the same - (even if you initially screwed up by drooping the RPM).
Nice work with the names there Flingwing!
Considering the start point of the thread, you'll have to come up with another one like 'Simone Squirrel' or 'Etienne Ecureil' now - or 'Anatole A-Star' for the Americans.
Considering the start point of the thread, you'll have to come up with another one like 'Simone Squirrel' or 'Etienne Ecureil' now - or 'Anatole A-Star' for the Americans.
wow flingwing - you really an instructor?
wow flingwing - you really an instructor?
I strongly suggest you review those text books with your mates. Perhaps you could quote them here because your conclusions do not match current aerody theory. There is a real difference between LTE and rotor drooped LTA, Loss of control or loss of thrust.
And guess what - they all have different recovery requirements, no matter how much you and your buddies decide it is all so simple.
Smash -
Mate that is not LTE, though let me assure you, LTE does exist. If you are putting in left pedal, that is due to streamlining unloading the T/R by enabling the vertical fin to provide some thrust and translational lift reducing inducd power, nothing to do with LTE, LTA, etc. The T/R is working too well, not well enough. Call it translational lift.
wow flingwing - you really an instructor?
I strongly suggest you review those text books with your mates. Perhaps you could quote them here because your conclusions do not match current aerody theory. There is a real difference between LTE and rotor drooped LTA, Loss of control or loss of thrust.
And guess what - they all have different recovery requirements, no matter how much you and your buddies decide it is all so simple.
Smash -
Mate that is not LTE, though let me assure you, LTE does exist. If you are putting in left pedal, that is due to streamlining unloading the T/R by enabling the vertical fin to provide some thrust and translational lift reducing inducd power, nothing to do with LTE, LTA, etc. The T/R is working too well, not well enough. Call it translational lift.
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Well, helmet fire, here's the FAA line (AC 90-95).
THE PHENOMENA OF LTE.
LTE is a critical low-speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control.
When they say "does not subside of its own accord", does this mean "without pilot input", or "even with the proper input"? So, Sammy Schweizer;s yaw stopped as soon as he was into the wind. He was just slow on the pedals. LTE?
Rebecca could well have just applied insufficient left pedal as she passed through ETL and raised collective. LTE?
Joey on the other hand experiences a rapid yaw, and even WITH application of the corrective action, is unable to stop it. What else to call this? LTE?
So when you droop your rotor RPM, and then you experience an uncommanded yaw rate which does not subside on its own accord, AND you can't stop it with the pedals, by the FAA definitions, you are experiencing LTE. The low RPM might have gotten you there, but you are there all the same.
The Rotorcraft Flying Handbook and AC 90-95 both describe low RPM as one of the contributors to LTE, along with hot & high, heavy GW, low speed, downwind ops, and right turns (in a CCW rotor helicopter). I didn't write the books, but as a CFI in the USA, I am bound to work within their guidelines.
You might be able to educate me here - if I am losing T/R thrust due to rotor droop, and I start yawing, would I not lower collective (as much as able), regain airspeed (as much as able) fly into the turn (as much as able) while applying opposite pedal?
THE PHENOMENA OF LTE.
LTE is a critical low-speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control.
When they say "does not subside of its own accord", does this mean "without pilot input", or "even with the proper input"? So, Sammy Schweizer;s yaw stopped as soon as he was into the wind. He was just slow on the pedals. LTE?
Rebecca could well have just applied insufficient left pedal as she passed through ETL and raised collective. LTE?
Joey on the other hand experiences a rapid yaw, and even WITH application of the corrective action, is unable to stop it. What else to call this? LTE?
So when you droop your rotor RPM, and then you experience an uncommanded yaw rate which does not subside on its own accord, AND you can't stop it with the pedals, by the FAA definitions, you are experiencing LTE. The low RPM might have gotten you there, but you are there all the same.
The Rotorcraft Flying Handbook and AC 90-95 both describe low RPM as one of the contributors to LTE, along with hot & high, heavy GW, low speed, downwind ops, and right turns (in a CCW rotor helicopter). I didn't write the books, but as a CFI in the USA, I am bound to work within their guidelines.
You might be able to educate me here - if I am losing T/R thrust due to rotor droop, and I start yawing, would I not lower collective (as much as able), regain airspeed (as much as able) fly into the turn (as much as able) while applying opposite pedal?
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Flingwing207,
Your logic, if carried to extreme:
If you bash your tail cone into a mountain along the right side, and your aircraft yaws right and "does not subside of its own accord and, if not corrected, can result in the loss of aircraft control." So I guess if you hit a mountain, you experience LTE!
If you pull the rotor rpm down to your socks because you requested too much power, and you are too numb to the cues that your aircraft is screaming at you, you have LBP, loss of brain power. If you treat it as a yaw problem, you have so purely missed the point contained in "pilot in command" that perhaps it is time to hang it up.
The reason why the distinction is made is that the causes and cures are different, as is the aerodynamics. If you blur it all together, you will never actually understand nor control your environment. I know of pilots who lost roll control due to rpm droop, should we call that LCE loss of cyclic effectiveness?
Your logic, if carried to extreme:
If you bash your tail cone into a mountain along the right side, and your aircraft yaws right and "does not subside of its own accord and, if not corrected, can result in the loss of aircraft control." So I guess if you hit a mountain, you experience LTE!
If you pull the rotor rpm down to your socks because you requested too much power, and you are too numb to the cues that your aircraft is screaming at you, you have LBP, loss of brain power. If you treat it as a yaw problem, you have so purely missed the point contained in "pilot in command" that perhaps it is time to hang it up.
The reason why the distinction is made is that the causes and cures are different, as is the aerodynamics. If you blur it all together, you will never actually understand nor control your environment. I know of pilots who lost roll control due to rpm droop, should we call that LCE loss of cyclic effectiveness?
Can I have some confirmation or denial of the following, which summarises what I've read and heard about the phenomenon known as LTE:
a. Is associated with the Bell 206
b. Happens in a high left pedal demand situation at low speed
c. Is thought to be 'set off' by the not-very effective tail rotor operating at normal rpm encountering dirty air from either the main rotor vortices, or ingesting its own vortices
d. Is more likely when the relative wind comes from certain critical directions (ties in with 'c')
e. Is characterised by a very rapid right yaw that can't be stopped with left pedal
f. Can perhaps be flown out of as described by flingwing, given room to lower collective and gain airspeed, but will probably only be stopped by rolling off the throttle or crashing, or both.
Lots of definitions and acronyms being thrown around in this discussion; are these points a fair summary or not?
a. Is associated with the Bell 206
b. Happens in a high left pedal demand situation at low speed
c. Is thought to be 'set off' by the not-very effective tail rotor operating at normal rpm encountering dirty air from either the main rotor vortices, or ingesting its own vortices
d. Is more likely when the relative wind comes from certain critical directions (ties in with 'c')
e. Is characterised by a very rapid right yaw that can't be stopped with left pedal
f. Can perhaps be flown out of as described by flingwing, given room to lower collective and gain airspeed, but will probably only be stopped by rolling off the throttle or crashing, or both.
Lots of definitions and acronyms being thrown around in this discussion; are these points a fair summary or not?
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Anyone care to anal-ize this report?
KAUAI News
Helicopter crash report a case of 'he said, he said'
By Andy Gross - THE GARDEN ISLAND
The circumstances surrounding the fatal Heli USA Airways crash Sept. 23 off the Ha'ena Coast remains a "he said, he said," situation.
According to a preliminary report issued Tuesday by investigators with the National Transportation Safety Board (NTSB) and compiled by lead investigator Debra Eckrote, Heli USA pilot Glen Lampton told investigators the Heli USA Airways Aerospatiale AS 350BA, N355NT (registered to Jan Leasing LLC, of Las Vegas, Nevada) was at 2,000 feet flying along Na Pali Coast toward Kailiu Point. Lampton said he had encountered some weather in Waimea Canyon.
According to the preliminary report, as the flight approached Ke'e Beach, Lampton noted rain showers which appeared to be offshore. As he came around the point, Lampton said he "suddenly saw a MD500 coming straight for me." He made a left turn to avoid the traffic, and as the helicopter leveled out, it encountered heavy rain.
Based on interviews, other pilots, including Ian Bagano, who was at the helm of an McDonnell Douglas 500 (MD500, or Hughes 500D) owned by Inter-Island Helicopters, were at about 300 feet above sea level, getting out of the weather.
Bagano said he was well below 2,000 feet during this course reversal, and it wasn't until he was near Hanakapi'ai Beach, several miles to the southwest of the Kailiu Point, before he heard Lampton's mayday call.
Eckrote said she had no hard data to support the eyewitness accounts of the pilots. She said there was no radar operating in that area.
The preliminary report is a narrative, and does not draw conclusions. It is based upon interviews with pilots and other personnel, none of whom are identified in the report.
Eckrote said she hoped to have the final report finished in three to six months.
According to NTSB officials, the preliminary information is subject to change, and may contain errors which will be corrected when the final report has been completed.
During preliminary interviews and a subsequent written statement, Lampton reported that, at the completion of his lunch break, he spoke with a representative at the Princeville Heli USA Airways base, who reported no adverse weather conditions.
Preliminary interviews with other air-tour-operator pilots in the area reported that the weather off of the Kailiu Point had been building all day.
Eckrote said that, because there is no weather station in the vicinity, pilots had to depend upon each other's reports.
Lampton told NTSB investigators he could still see down and to the right to the coastline. The pilot opted to reduce airspeed to 60-80 knots, and started a 15-to-20-degree right turn over the beach. The helicopter got about 160 degrees into the turn when the airspeed went to zero and the aircraft started to rapidly descend. Lampton attempted to control the helicopter with control inputs, which had no effect.
The pilot stated that he realized that they were going to hit the beach, and applied full power. The rate of descent suddenly stopped, and the helicopter went back up in the air momentarily, and entered an immediate hard spin to the left. According to the report, Lampton instructed the passengers to open the doors, and he transmitted a mayday call as the helicopter impacted the water, bounced back into the air, then impacted the water again, still spinning, but remaining on the surface for a short time before it eventually rolled to the right.
At approximately 2:15 p.m. the Heli USA copter hit the ocean several hundred yards off the coastline at Ke'e Beach, near Ha'ena.
The flight encountered instrument meteorological conditions just prior to the accident.
According to Zoe Keliher of the NTSB, Lampton was not instrumentrated. A company flight plan was in effect. The pilot and two passengers received minor injuries. The remaining
three passengers were fatally injured. The flight departed from Lihu'e Airport at 1:54 p.m. for the intended 45-minute tour.
Lampton reported that the weather was good until he reached Waimea Canyon. Clouds were present in the canyon, therefore he exited the area at the lower microwave station, near the entrance to the canyon, and proceeded to Na Pali Coast.
The pilot flying a tour about 15 minutes prior to the accident said that he encountered the rain at the Kailiu Point and made a gradual descent to about 300 feet above ground level. The pilot was able to maintain visual reference with the coastline, and continued on his tour route.
According to the NTSB preliminary report, this pilot reported no encounter with turbulence, downdrafts, lightning or windshear, while maneuvering through the rain. One other pilot in front of the MD500 and doomed Heli USA craft also reported that he entered the rain shower and descended to 300 feet just past Ke'e Beach before he made a course reversal due to deteriorating visibility.
According to the preliminary report, Bagano also reported encountering the rain showers, and he too made a controlled descent to a lower altitude to maintain ground reference. The visibility decreased to a point where he, too, opted to reverse course.
Based upon earlier reports, the two surviving passengers, Karen Clifton, 44, and her husband Bill Thorson, 48, said they didn't believe Lampton had to maneuver to avoid hitting the other helicopter. They said they saw a helicopter below them.
KAUAI News
Helicopter crash report a case of 'he said, he said'
By Andy Gross - THE GARDEN ISLAND
The circumstances surrounding the fatal Heli USA Airways crash Sept. 23 off the Ha'ena Coast remains a "he said, he said," situation.
According to a preliminary report issued Tuesday by investigators with the National Transportation Safety Board (NTSB) and compiled by lead investigator Debra Eckrote, Heli USA pilot Glen Lampton told investigators the Heli USA Airways Aerospatiale AS 350BA, N355NT (registered to Jan Leasing LLC, of Las Vegas, Nevada) was at 2,000 feet flying along Na Pali Coast toward Kailiu Point. Lampton said he had encountered some weather in Waimea Canyon.
According to the preliminary report, as the flight approached Ke'e Beach, Lampton noted rain showers which appeared to be offshore. As he came around the point, Lampton said he "suddenly saw a MD500 coming straight for me." He made a left turn to avoid the traffic, and as the helicopter leveled out, it encountered heavy rain.
Based on interviews, other pilots, including Ian Bagano, who was at the helm of an McDonnell Douglas 500 (MD500, or Hughes 500D) owned by Inter-Island Helicopters, were at about 300 feet above sea level, getting out of the weather.
Bagano said he was well below 2,000 feet during this course reversal, and it wasn't until he was near Hanakapi'ai Beach, several miles to the southwest of the Kailiu Point, before he heard Lampton's mayday call.
Eckrote said she had no hard data to support the eyewitness accounts of the pilots. She said there was no radar operating in that area.
The preliminary report is a narrative, and does not draw conclusions. It is based upon interviews with pilots and other personnel, none of whom are identified in the report.
Eckrote said she hoped to have the final report finished in three to six months.
According to NTSB officials, the preliminary information is subject to change, and may contain errors which will be corrected when the final report has been completed.
During preliminary interviews and a subsequent written statement, Lampton reported that, at the completion of his lunch break, he spoke with a representative at the Princeville Heli USA Airways base, who reported no adverse weather conditions.
Preliminary interviews with other air-tour-operator pilots in the area reported that the weather off of the Kailiu Point had been building all day.
Eckrote said that, because there is no weather station in the vicinity, pilots had to depend upon each other's reports.
Lampton told NTSB investigators he could still see down and to the right to the coastline. The pilot opted to reduce airspeed to 60-80 knots, and started a 15-to-20-degree right turn over the beach. The helicopter got about 160 degrees into the turn when the airspeed went to zero and the aircraft started to rapidly descend. Lampton attempted to control the helicopter with control inputs, which had no effect.
The pilot stated that he realized that they were going to hit the beach, and applied full power. The rate of descent suddenly stopped, and the helicopter went back up in the air momentarily, and entered an immediate hard spin to the left. According to the report, Lampton instructed the passengers to open the doors, and he transmitted a mayday call as the helicopter impacted the water, bounced back into the air, then impacted the water again, still spinning, but remaining on the surface for a short time before it eventually rolled to the right.
At approximately 2:15 p.m. the Heli USA copter hit the ocean several hundred yards off the coastline at Ke'e Beach, near Ha'ena.
The flight encountered instrument meteorological conditions just prior to the accident.
According to Zoe Keliher of the NTSB, Lampton was not instrumentrated. A company flight plan was in effect. The pilot and two passengers received minor injuries. The remaining
three passengers were fatally injured. The flight departed from Lihu'e Airport at 1:54 p.m. for the intended 45-minute tour.
Lampton reported that the weather was good until he reached Waimea Canyon. Clouds were present in the canyon, therefore he exited the area at the lower microwave station, near the entrance to the canyon, and proceeded to Na Pali Coast.
The pilot flying a tour about 15 minutes prior to the accident said that he encountered the rain at the Kailiu Point and made a gradual descent to about 300 feet above ground level. The pilot was able to maintain visual reference with the coastline, and continued on his tour route.
According to the NTSB preliminary report, this pilot reported no encounter with turbulence, downdrafts, lightning or windshear, while maneuvering through the rain. One other pilot in front of the MD500 and doomed Heli USA craft also reported that he entered the rain shower and descended to 300 feet just past Ke'e Beach before he made a course reversal due to deteriorating visibility.
According to the preliminary report, Bagano also reported encountering the rain showers, and he too made a controlled descent to a lower altitude to maintain ground reference. The visibility decreased to a point where he, too, opted to reverse course.
Based upon earlier reports, the two surviving passengers, Karen Clifton, 44, and her husband Bill Thorson, 48, said they didn't believe Lampton had to maneuver to avoid hitting the other helicopter. They said they saw a helicopter below them.
zdfwflyer: i would care to comment....that report is totally irrelevant to the thread, however i am sure that flingwiing can safely conclude it was an LTE event that caused the accident, after all, it hit the water and spun uncontrollably left.
AOTW,
Some points on your summary;
95% of LTE have been on B206, as Nick points out. Bell claim it is not limited to the 206, but few other types have had a record of the event. This ties in with the claim of "a new aerodynamic theory or phemomena" rather than any acceptance of deisgn flaw.
re your point 'f", the recovery technique was as you say. A 1995 ish B206 accident in the Australian Army was an LTE event and the pilot did just that - he tried to lower lever but had insufficient height, and then rolled the throttle off in accordance with the checklist procedure, writing the aircraft off and sustaining injury to himself and his pax. The checklist actions were reviewed and the recommendation was to lower the lever if hieght permits, otherwise attempt a flyaway using out of turn cyclic rather than roll the throttle off, particularly when faced with adverse terrain. I dont know if Bell ratified this recommendation, but it certainly makes sense. The danger is trying to discern LTE from Loss of T/R thrust whilst you are spinning around madly staining your shorts.
As a sideline, senior pilots very unfairly critised the junior pilot involved who carried out the taught checklist procedure to perfection in harrowing circumstances. well done that man. He did what the senior pilots had taught him, and what Bell recommended. Where do they get off??
AOTW,
Some points on your summary;
95% of LTE have been on B206, as Nick points out. Bell claim it is not limited to the 206, but few other types have had a record of the event. This ties in with the claim of "a new aerodynamic theory or phemomena" rather than any acceptance of deisgn flaw.
re your point 'f", the recovery technique was as you say. A 1995 ish B206 accident in the Australian Army was an LTE event and the pilot did just that - he tried to lower lever but had insufficient height, and then rolled the throttle off in accordance with the checklist procedure, writing the aircraft off and sustaining injury to himself and his pax. The checklist actions were reviewed and the recommendation was to lower the lever if hieght permits, otherwise attempt a flyaway using out of turn cyclic rather than roll the throttle off, particularly when faced with adverse terrain. I dont know if Bell ratified this recommendation, but it certainly makes sense. The danger is trying to discern LTE from Loss of T/R thrust whilst you are spinning around madly staining your shorts.
As a sideline, senior pilots very unfairly critised the junior pilot involved who carried out the taught checklist procedure to perfection in harrowing circumstances. well done that man. He did what the senior pilots had taught him, and what Bell recommended. Where do they get off??
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In the UK the CAA released a FODCOM (Jan 04) after 2 "LTE" filming incidents in 03. The FODCOM of course made no reference to the facts that the two machines involved were 206 models.
A year later (!!) the BBC released an internal Health & Safety Alert to all production departments, referring to the CAA alert and stating that all productions must ask any helicopter operator they book a series of questions about LTE.
What a mucking fuddle that caused. It flashed up on the BBC internal email system as a major alert making everyone drop their media glasses onto the tips of their noses and panic. Suddenly, all helicopters were going to kill you.
God save us from the clipboard and box-ticking mentality.
LTE isn't a cause of accidents. It's a symptom of bad driving.
A year later (!!) the BBC released an internal Health & Safety Alert to all production departments, referring to the CAA alert and stating that all productions must ask any helicopter operator they book a series of questions about LTE.
What a mucking fuddle that caused. It flashed up on the BBC internal email system as a major alert making everyone drop their media glasses onto the tips of their noses and panic. Suddenly, all helicopters were going to kill you.
God save us from the clipboard and box-ticking mentality.
LTE isn't a cause of accidents. It's a symptom of bad driving.