R44 down Rio de Janeiro
|
a good place for a soft crash eh
|
Quite a rare but instructive video of how quickly LTE bites if the chopper is slow and the wind is wrong and there's very little height to recover from except try and do one or more of the following:
1. closing the throttle and reducing collective 2. "milk" the collective 3. flying into the direction of the turn 4. doing an auto once there is any airspeed but I think none of these would work for this poor guy. It's all very easy to say one should never get oneself into this position but what other escape methods does one have ? I'd be keen to hear from anyone who has done extensive research into this area (as I have) or has been through a similar situation. Thanks in advance. |
Dangerous mis-understanding
LTE (Education) - LTRED
Presuming there was no mechanical fault (loose article in control run?) This appears to be a classic case of 'the education problem'. I hope no-one was injured. The Airspeed becomes negative (due to the classic accidentally downwind app) The weathercocking is unexpected a small and timid input is ineffective the pilot becomes confused despite the input he has made the helicopter appears to be responding in the wrong direction. The pilot makes drastic and confused control inputs and sometimes crashes. - most pilots suffer this educational stage at some point and learn to be authoritative. There are many examples of this (class) of accident/incident (LTEd): Australian film pilot (looses 2000ft whilst confused) Irish wedding squirrel EC120 Redhill (more or less) Gazelle in Yorkshire (fatal) The R44 does not run out of pedal at zero A/S - you just need to use the pedals. At Airspeed the situation is improved - with the worst pilot screw up the most you'd have to turn is 180 deg..... - the action suggested by RF might be a little drastic for a serviceable helicopter, where the pedals just need 'subtle manipulation' to arrest yaw. |
Crash landing in a fairground and on top of an inflatable slide!
Mickjoebill |
Thanks AnFI for your input. As a matter of fact, I agree with your comments:
learn to be authoritative R44 does not run out of pedal at zero A/S Cheers. |
that is true too, and if all else fails, try my aforementioned "drastic actions" ! |
R22LTE
I got into it at 400 agl(photo flight), completely my fault. := I WAS trying to stay above 20 kts, but I failed to do that. Spun 3 times in 3 seconds, full left pedal, and it felt like I was holding a tiger that wanted to break free. Fighting to keep it from spinning, with full left pedal, and that sorta worked, pulled a bit of collective, got a low RPM horn, OK that didn't work, down collective, while fighting the pedals again, tail rotor sounds like I had never heard before, nosed it over to get forward airspeed, with no response, nosed it over again to about a 60 degree down angle, yawing back and forth, and finally got it back at 50 agl over the beach. Got out of the 22 10 min. later at the airport, and the seat was still attached to my behind! THEE LONGEST 15 SECONDS OF MY LIFE. My photog hit my knee and said GOOD JOB, that was FUN! IF he only knew!
|
I WAS trying to stay above 20 kts, but I failed to do that. Was it 20kts downwind or reducing airspeed to possibly being in the negative? Did you make large collective inputs due to losing ETL (with big change in torque as a result) with feet not being able to follow? Happy to learn, Helldog |
Yes, for me 20-23 kts airspeed would have been ideal....
What would you say would be the main reason for losing tail rotor control in your case? Was it 20kts downwind or reducing airspeed to possibly being in the negative? Did you make large collective inputs due to losing ETL (with big change in torque as a result) with feet not being able to follow? Unless I am directly into the wind, will I drop it below 20 kts forward airspeed to get a shot. I know I introduced it to myself, and I've since forgiven myself for it, but I will never forget that experience, and lesson learned! Hope this helps! Rob |
it doesn't look like a TR failure...
|
Flag in background appear to support the LTE. Brisk wind away and slightly to right of camera. The acceleration and deceleration of the turns. Interesting 'high pitched' whine down just at onset of spin. Pilot induced?
That low over people? Duh! Full left pedal, lower collective to gain airspeed and reduce torque in the altitude you have. Not much option. In fact, don't be there in first place is only option. Sorry for the kids who didn't get their turn on the bouncy castle. |
1. closing the throttle and reducing collective 2. "milk" the collective 3. flying into the direction of the turn 4. doing an auto once there is any airspeed but I think none of these would work for this poor guy. |
Why would you want to close the throttle? |
Quote: Why would you want to close the throttle? The idea is of course to REDUCE TORQUE. If that means reducing pitch, you must lower collective, which in turn should be accompanied by an appropriate closing of the throttle. However, it is important that the 'throttle' is not the cause, and so cutting the engine completely is NOT necessary. More importantly, and Rotor RPM droop will result in tail rotor RPM droop. This is undesireable. Keep RPM up. LTE recovery is simple and systematic. FAA Rotorcraft Flying Handbook If a sudden unanticipated right yaw occurs, the following recovery technique should be performed. Apply full left pedal while simultaneously moving cyclic control forward to increase speed. If altitude permits, reduce power. As recovery is effected, adjust controls for normal forward flight. Collective pitch reduction aids in arresting the yaw rate but may cause an excessive rate of descent. Any large, rapid increase in collective to prevent ground or obstacle contact may further increase the yaw rate and decrease rotor r.p.m. The decision to reduce collective must be based on your assessment of the altitude available for recovery. If the rotation cannot be stopped and ground contact is imminent, an autorotation may be the best course of action. Maintain full left pedal until the rotation stops, then adjust to maintain heading. *Edit* - You say your 1-4 response is regurgitating the FM? Is that really what the R44 manual says? I'm surprised. FAA certified aircraft! FAA Advisory Circular - AC 90-95 - Unanticipated Right Yaw in Helicopters |
Collective pitch reduction aids in arresting the yaw rate but may cause an excessive rate of descent. The decision to reduce collective must be based on your assessment of the altitude available for recovery. 1-4 response is regurgitating the FM? Cheers. |
Use the controls for their purpose....
He only needed to move the left pedal forward ... to prevent the rotation to the right.
The R44 does not run out of left pedal - but pilots do get confused - as is clear from this thread..... many questionable solutions proposed here. Most pilots learn this - most often by being caught out, and then becoming more authoritative. There are many accidents from this cause - the fatal Gazelle accident in Yorkshire was most probably an example.... |
ReverseFlight,
Dude. You listed four recovery actions. One of them was 'closing the throttle'. While your post explains that these are 'beyond' the recommended techniques for use in low altitude / airspeed situations, you clearly caused some confusion for others. Some people asking why the 'throttle must be closed'. Instead of explaining and clarifying your list, you replied with what I can presume was an attempt at poorly written sarcasm, which caused more confusion. I think you'd better read YOUR post more carefully. Someone Asked: Why would you want to close the throttle? ReverseFlight said: Apologies for regurgitating the FM. At the rate of rotation in the video, there is no need to close the throttle. Agree. You'll note that those techniques therefore state a complete recovery chain, rather than scenario specific actions. It also provides warnings regarding LTE at low altitude. Since it is important to keep the entire section together, so no one can take any part out of context (as you have done), I'll repost it all here. FAA Rotorcraft Flying Handbook If a sudden unanticipated right yaw occurs, the following recovery technique should be performed. Apply full left pedal while simultaneously moving cyclic control forward to increase speed. If altitude permits, reduce power. As recovery is effected, adjust controls for normal forward flight. Collective pitch reduction aids in arresting the yaw rate but may cause an excessive rate of descent. Any large, rapid increase in collective to prevent ground or obstacle contact may further increase the yaw rate and decrease rotor r.p.m. The decision to reduce collective must be based on your assessment of the altitude available for recovery. If the rotation cannot be stopped and ground contact is imminent, an autorotation may be the best course of action. Maintain full left pedal until the rotation stops, then adjust to maintain heading. If you have other techniques from dusty old videos, then be very clear, or you'll have people less learned than you closing throttles and milking collectives when all they need is APPLY FULL LEFT PEDAL. cl12p2s |
cl12pv2s
you must lower collective, which in turn should be accompanied by an appropriate closing of the throttle. you don't mean the pilot should partially close his twist grip do you? I think you must mean(?): "....and the correlator will close the throttle (butterfly valve) by the appropriate amount - reducing the torque but leaving the RRPM unaffected." ??? |
can I double check that with you... you don't mean the pilot should partially close his twist grip do you? I think you must mean(?): "....and the correlator will close the throttle (butterfly valve) by the appropriate amount - reducing the torque but leaving the RRPM unaffected." ??? Yes, that is exactly what I mean. In an LTE situation, RPM must be maintained, but power reduced. Lower the collective, and maintain RPM. Someone else might chip in more, but that's how I learnt it. |
It's clear that the pilot has LTE: But is that really the problem? I would bet good money that the low RRPM horn went off around the time "LTE" started and that the pilot ran out of power, which initially expressed itself as right yaw. The so-called LTE video in Australia is a good example of this, with in-cockpit evidence of how the event sequence developed.
AnFI It is a while since I read the Gazelle accident in Yorkshire, but I can't remember that it was attributed to LTE in any singular and causal sense. The decision to fly given the dangerous wind conditions, together with the pilot's inexperience, were fundamentally what killed Paul and his wife. In the Rio video, the pilot had surely passed the commital point without realising he was about to crash. LTE caused the aircraft to spin, but what caused the LTE and why did the aircraft crash? There is surely more afoot in this video than LTE. |
Hi Torquetalk, you said:
I would bet good money that the low RRPM horn went off around the time "LTE" started and that the pilot ran out of power, which initially expressed itself as right yaw. Thanks in advance. |
Basic Handling Education - I think......
LTE in this case is clearly Lack of Tailrotor Education
The R44 tail rotor does not run out of effectiveness The R44 tail rotor does not run out of effectiveness (unless there is some other factor: blocked pedal with telephone .... etc) It is a common error to get the wind 'wrong' by 180 deg.... ... when the behavior of the helicopter no longer makes sense the pilot's brain can seize. He does press the left pedal but is too timid - he fails to get the response he expects - worse : he appears to get the opposite effect , as the weather-cocking increase beats his yaw response rate - the RIGHT yaw rate increases co-inciding with the (timid) rate at which he is applying LEFT pedal - the pedals appear to be working in reverse - he changes his strategy (after about 120degrees) presses the right pedal - the yaw continues through 'into wind' to 'tail wind' again and the pilot is out of control. (Just like the Australian Video - link please). (spinning helicopter, airspeed tends to zero - more power is required to sustain a hover - more left pedal is required than would previously have been sufficient (still no shortage of available T/R thrust)) If the pilot attempts any drastic actions at this stage he will probably be causing himself further problems (... like the Australian case where the pilot CLOSES THE THROTTLE :=- the RRPM fall to an extra-ordinary low rate, 50%!? (measure it..) fortunately there is enough time for the pilot to stop trying to do anything and the pilot discovers that everything is working just fine, without any pilot input, recovery results). In Rio at 23.7 seconds this pilot attempts quite a hard but brief press on the left pedal which results in a small RRPM droop - the horn and buzzer come on (futher overloading our cautious aviator's brain) - at 24 seconds the pilot responds (almost instantly) to the horn by dumping the lever (as he has been pre-programmed to do) watch the helicopter drop sharply by about 10feet corresponding to an almost complete dumping of the lever for a short time. The helicopter approaches the (not so) soft landing cushion and its pilot is already mentally committed to crashing because he is so confused. He fails to realise that the helicopter is not really yawing much anymore and is in a totally controllable state - resigned however - and with insufficient height to have the time to realise NOTHING IS WRONG - he continues with his pointless crash. :eek::confused::uhoh::mad::ouch::( This is L T Ed It is a while since I read the Gazelle accident in Yorkshire, but I can't remember that it was attributed to LTE in any singular and causal sense. BUT i don't know - i wasn't there.... They are unlikely to conclude that since "LTEd" is not really recognised/taught. I think the recommendations implied the Yorkshire accident was something to do with being taught in a "Registered Facility" on a Turbine instead of at a Type Rating Training Organisation - I think - and paperwork had not been correctly addressed and so it was recommended that there should be more oversight of training by the NAA - some rules were changed etc... The R44 tail rotor does not run out of effectiveness .... does anyone know the PA and temperature of this accident? |
I don't agree I am afraid, the TR at full left pedal eats the rrpm and the horn goes off, possible to get out of at a few hundred feet but tricky at 50 feet, it happens very very quickly:ooh:
|
The R44 tail rotor does not run out of effectiveness |
Disagree Rotorboater....
It is ONLY pilot handling inexperience/inability through lack of exposure.
Pressing the left pedal (see my long boring analysis of the accident) did result in droop and at 24secs the pilot 'dumped the lever' for 1 second (unnecessarily) in response - all part of being out of control. No height need be lost - if you use the lever to keep the height and the cyclic to keep level and press pedal as required to stop yaw - you will not have a problem. It does not matter if the droop causes the horn to come on - since the engine is able to deliver more power the governor will add it (even if the pilot does not help it by adding throttle as required) the temporary RRPM droop does not threaten flight (and need not alter the height at all). Ideally pilots should be able to distinguish the difference and preserve RRPM when the engine cannot deliver sufficient power to maintain RRPM - if the engine is working and the droop is temporary due to rapid pedal application then lowering the lever does not really help - it just makes you go down... remember lowering the lever closes the butterfly also... You do not need to lose height when you lose 'grip' of the yaw... It is more appropriate to stop yaw by using the pedals than keeping them still and lowering the lever! It is only pilot mis-handling... |
unless
there was a defect or if hot and high? Carb or Injected?
|
The Problem is not tail rotor,The problem is not power,The problem is people with $$$$$ and no piloting skills or any idea on what's safe, A total waste of a nice machine.
|
hillberg
true true - (though some good people do not have the handling skills)
|
Fly aeroplanes....there much safer :ok: Helicopters FREAK ME OUT :=
|
The R44 tail rotor does not run out of effectiveness Unless this guy was hot and high it seems unlikely that he runs out of power (he is single pilot, no pax) unless he has some sort of engine/magneto problem. |
You'll be saying that then to the HEMS chaps when there about to get you to hospital after your shunt on the motorway I take it? :confused:
|
Crab - strictly true but not relevant since...
the engine also is capable of producing less torque (approximately linear with RPM) - the tail rotor is so over capable that it still has the capacity to counter the torque... even at a hideous:eek: level of low RRPM
(T/R effectiveness being proportional to the Square of RRPM.... the 'crossover' is VERY LOW) |
Fly aeroplanes....there much safer Helicopters FREAK ME OUT Just needs to go back to school and learn to spell. |
Reverse - If LTE is caused by an unfavourable vector, the aircraft torque reaction will accelerate to a given rate in nil wind. “LTE” caused by low TRRPM isn’t really LTE in this sense. In a moment of particular stupidity, I presented the TR of an R22 to a 40 KT wind and it spun so hard that it was clear that fighting the yaw with the pedal was pointless: it was easier to catch as the boom came back into wind: Pilot-induced LTE :O
The cause of the Rio accident remains to be determined. But there are a LOT of R44 accident videos which appear to share the same problem: over-pitching on approach to land. The “LTE” in these videos may be a secondary symptom of running out of power: More collective, excessive coning angle; decaying RRPM, more yaw;. As Rotorboat has pointed out; when this starts it will develop very quickly. Crab - The correlator/governor system in the R44 can be response-rate variable aircraft-to-aircraft, and droop is, in-any-case, not hard to bring about. With 3 PAX and half a tank of fuel at sea level it is easy to over-pitch if the power requirement is high. A bit odd if only one person onboard admittedly; but downwind, high, hot; rapid lever application: still wouldn’t rule it out. There is a very unhappy conjunction with respect to the R44 involving poor training and overconfidence in the performance of the aircraft. AnFI - I don’t know where you get the idea that the pilot in the Australian “LTE” video closed the throttle. Having seen the video many times and used it for teaching: this is news to me. The Yorkshire Gazelle accident is also not to be hijacked as an LTE accident: the investigators looked at a variety of possible factors which may have been contributory, of which LTE was discussed. Of no less importance was the stability of the aircraft type in difficult wind conditions (which were certainly present); and instructor over-confidence in a highly confident pilot with virtually no rotorcraft experience. Having known Paul, the report struck me as a thorough and balanced assessment of the information available. It was a very sad and unnecessary episode. Please do not cherry-pick a report to indulge in your current favourite subject. |
Torquetalk, I agree that in a lot of R44 accidents the cause of the low rrpm horn going off were probably as a result of over-pitching rather than the LTE itself.
Assuming nil (rather than your 40 kt) wind then, could full LTE develop without the horn going off ? Picture the MRs turning anti-clockwise for the R44 and the main fuselage turning clockwise during LTE. Is the MR rrpm not referenced to the fuselage ? As the fuselage is turning the other way (clockwise), the tacho could sense that rrpm is sufficient. However, aerodynamic wise, the MR blades could be turning much slower (even without over-pitching) and this may not be sufficient for continued flight, even though the LTE itself would have the effect of off-loading power from the TR (thus producing more power for MR thereby creating lift). This is just a theory as I have no figures to back up. Maybe someone out there does. |
In Summary ? - And One way pads.
Firstly here's my 2 cents worth.
Not to be too nit picky, [email protected] (he is single pilot, no pax) Torqutalk AnFI - I don’t know where you get the idea that the pilot in the Australian “LTE” video closed the throttle. Having seen the video many times and used it for teaching: this is news to me. AnFI In Rio at 23.7 seconds this pilot attempts quite a hard but brief press on the left pedal which results in a small RRPM droop - the horn and buzzer come on Where do you get this info from or is it speculation ? In Summary - Do we have a general consensus on what more than likely happened here ? Un-arrested right yaw - Caused by lack of left pedal, due to machine weather cocking ? Overpitching leading to LTE LTE - due to a quartering tail wind ? Because to be honest I am stumoed after reading all of this. :ugh: Please note: Definitely not having a go or being rude toward anybody here, just looking to learn. Now to my original question. How to land at a one way pad, heavy with the wind behind you without getting into this situation ? (Admittedly if this guy was trying to land downwind he had way too much G/S on.) Here's a brief run-down. 1.Come to a hover into some degree of headwind element perpendicular to the pad or so. 2.Pedal turn toward pad 3.And very slowly drift in over the pad to land. Look forward to everybody's genuine input. Regards Loachy :confused: |
Reverse – The torque reaction is resolved by removing engine power: closing the throttle or entering auto. The disk fuselage may then follow the rotor direction then due to friction (right pedal needed in auto). Torque reaction shouldn’t be a function of RRPM but an opposite and equal reaction to the power supplied by the engine to overcome total drag.
My understanding is that LTE is independent of RRPM as its cause is unfavourable wind vectors and affects certain aircraft more than others. In the same sense, it’s hard to see how it could occur in nil wind if not in connection with overpitching/running out of power. Loachy – thanks for the clarification re. numbers: If that is so, then it was always going to be a difficult approach and landing and the pilot was stupid to approach downwind. If that was the only available approach, then it should only have been attempted with less weight and having conducted a power check to assure a sufficient power margin. My [genuine] take on it is than this is basically a power/overpitch problem. The tail boom may have been pushed by the wind and he may have reacted too slowy etc etc: but the odds of running out of power with 4 in an R44, downwind, steep, into a confined area are very high indeed. Of course, this IS speculation: we won't have the facts until the report is out. But as said before, it bears all the hallmarks a dozens of similar R44 crashes. Re. approach method: TBH it doesn’t really matter if you haven’t got the power to carry it out… |
At 90% Rotor RPM the tail rotor will never keep heading when you're pulling max pitch, With a full load, At High DA & A tail wind.:ugh:
The Low RPM horn is too late when you have allready lost control.:{ |
Hillberg
A tail wind pulling max pitch With a full load and..... Does the High DA make much difference to yaw control - since the engine and TR both perform proportional to Density? At MAX PITCH and at High DA (low engine power?) with the RRPM already at 90% (and being at max pitch presumably decreasing rapidly....? ) the last of your worries is yaw - since you are crashing anyway for other reasons - but I still think the TR is powerful enough to counter any yaw short of actually having to crash to prove the tail rotor inadequate... This guy in Brazil may have had any number of reasons to be unable to control his yaw - pax interference, wide shoes, object jammed in control run, mis-rigged pedals. BUT running out of T/R authority ain't one of them. I think (almost) all pilots will have a similar problem to this when they encounter whilst inexperienced the extreme unexpected yaw of an unexpected tail wind catching them out. Most are lucky .... In Yorkshire arriving at minus 20kts whilst not expecting it would be a schock ... that type is very stable into wind - the windier the better - the simple common pilot error of arriving downwind - makes the type very unstable in yaw at negative airspeed. There are so many yaw incidents - Auz, redhill120, swansea120, gazelle, rio, irish wedding, - there might be some advatange into recognising a cause and helping people with some helpful advice - like: some ideas.... Fly with the 'relative wind' on the nose - ie crab as required to prevent need for sideways and backwards airspeeds.... Dont be shy to use the pedals more aggressively if you need to assert yaw control. If you don't understand what they are doing then be calm, smooth and respond slowly if you need to. Stay level with the stick - regardless of the yaw rate. Keep the height with the lever. It's probably not a T/R failure. It's probably not an Engine Failure. Don't just give up and crash. The lever controls your height and the cyclic keeps the disk level - you'll figure out the rotation eventually.... Don't misdiagnose engine failure, if you hear the horn - be smooth. If you really have run out of pedal and it still just keeps yawing - then gently reduce the lever a little - and see if it helps - don't crash. Are you sure you are using full pedal and still spinning? Get more experience - soon |
All times are GMT. The time now is 12:04. |
Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.