R44 crashed - 4 heavily injured
Yes Crab is correct....did we not figure all this out on page 2?
Excellent video to use for learning purposes....I love it when things are caught film.
Excellent video to use for learning purposes....I love it when things are caught film.
So as a low-time R44 pilot, I'd like to ask a question here. The R44 is capable of an OGE hover at max gross close to sea level. So what are the circumstances that caused him to run out of power? Was it because he was descending fast as he lost ETL? Or what?
Thanks...
Thanks...
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does anyone know the density altitude on the day?
according to the HOGE chart here the R44 should be able to HOGE at MAUW up to 4500' on a standard day...
There is every chance he is above MAUW, or that the density altitude exceeds the HOGE performance, and that he ran out of power, but equally if he did lose tx lift from the treeline, or was downwind then I wouldn't rule our VRS, as surely his natural 'pull more collective to contain the sink' would have led to overpitch and the droop in Nr, and LTE that crab described?
Edit: I accept the ability to HOGE doesn't imply the ability to provide the extra power req'd to contain a rate of descent, but at lower density altitudes it should be possible... Either way it's obviously a badly selected/flown & rushed approach, showing very little concern for limited power and he got caught out
according to the HOGE chart here the R44 should be able to HOGE at MAUW up to 4500' on a standard day...
There is every chance he is above MAUW, or that the density altitude exceeds the HOGE performance, and that he ran out of power, but equally if he did lose tx lift from the treeline, or was downwind then I wouldn't rule our VRS, as surely his natural 'pull more collective to contain the sink' would have led to overpitch and the droop in Nr, and LTE that crab described?
Edit: I accept the ability to HOGE doesn't imply the ability to provide the extra power req'd to contain a rate of descent, but at lower density altitudes it should be possible... Either way it's obviously a badly selected/flown & rushed approach, showing very little concern for limited power and he got caught out
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Density altitude calculated here density altitude calculator
Density altitude 208 ft.
Village Altenbeken 298 m MSL = 978ft
QNH, Temp, from accident report of Airport EDLP 27 km away.
Density altitude 208 ft.
Village Altenbeken 298 m MSL = 978ft
QNH, Temp, from accident report of Airport EDLP 27 km away.
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n5296s
Look at Aucky's edit.
There is a difference between a static hover requirement and the power requirements in certain dynamics flight profiles.
As a more extreme example of this I'd like to refer the Nick Lappos statement that given sufficient power one can get out of VRS using power. In the given case no such power margins were available.
d3
edit : not implying that this was VRS, I also stand by Crab's summary.
There is a difference between a static hover requirement and the power requirements in certain dynamics flight profiles.
As a more extreme example of this I'd like to refer the Nick Lappos statement that given sufficient power one can get out of VRS using power. In the given case no such power margins were available.
d3
edit : not implying that this was VRS, I also stand by Crab's summary.
Last edited by delta3; 16th Dec 2010 at 23:53.
Having the power to hover OGE just isn't enough, especially for energetic manoeuvring, you really need to ensure you have an adequate thrust margin. In mil ops, generally a minimum of a 5% thrust margin is what you are looking for and, even if your RFM doesn't have a graph for this, it is easily calculated:
Work out your max weight OGE for your operating area and deduct 5% of that figure to give you an operating weight which will give you a sensible power margin. The correct way (and industry standard I believe) of doing this is to divide your weight by 1.05 but the difference in results between the 2 is small.
For the R44 at Maum of 2500 lbs that would give an operating weight of 2380 lbs (using 1.05) or 2375 lbs (using 5%).
All the above doesn't help when you mishandle the aicraft though.....doh!
Work out your max weight OGE for your operating area and deduct 5% of that figure to give you an operating weight which will give you a sensible power margin. The correct way (and industry standard I believe) of doing this is to divide your weight by 1.05 but the difference in results between the 2 is small.
For the R44 at Maum of 2500 lbs that would give an operating weight of 2380 lbs (using 1.05) or 2375 lbs (using 5%).
All the above doesn't help when you mishandle the aicraft though.....doh!
This post is addressed to the ppl's or low timers....with no disrespect meant whatsoever, if you wish to try something and learn from it...:
Based upon Crab's post:
It will not hurt...honest... Here is a demonstration I would make my students do many years ago:
Put your helicopter in a stabilized hover, (about two feet above the ground). Allow it to stabilize for a minute and note the power required. Now, WITHOUT moving the collective or moving from your spot, make the helicopter settle and "kiss" the skids on the ground.
The way to do it is by "stirring" the cyclic in an "energetic" way. It will give you an appreciation for being "smooth" on the controls.
Based upon Crab's post:
energetic manoeuvring
Put your helicopter in a stabilized hover, (about two feet above the ground). Allow it to stabilize for a minute and note the power required. Now, WITHOUT moving the collective or moving from your spot, make the helicopter settle and "kiss" the skids on the ground.
The way to do it is by "stirring" the cyclic in an "energetic" way. It will give you an appreciation for being "smooth" on the controls.
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the official crash report is out, unfortunately only in German You have to scroll down to page 35.
I would try to give a run-down, but I'm at the office and my boss might stop by
I will say, it was a private flight with special permission from the authorities; the designated landing site, a parking lot, had people on it so the pilot had to change is strategy, which then didn't work.
I would try to give a run-down, but I'm at the office and my boss might stop by
I will say, it was a private flight with special permission from the authorities; the designated landing site, a parking lot, had people on it so the pilot had to change is strategy, which then didn't work.
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As a more extreme example of this I'd like to refer the Nick Lappos statement that given sufficient power one can get out of VRS using power.
certainly the use of a swift flick on the collective will change the nice little formula for VRS that Nick has oft described if you manage to get it in the incipient stage. That's when or even before you first feel that sinking sensation, but immediately thereafter you will be sitting with an over pitched problem. Usually which is beyond the available power to sustain, so, recovery as per cattle truck's definition.
most mustering pilots encounter this little problem somewhere in their early career too close to the ground to lower collective and fly away, if they are lucky and the ground bump is not too hard after perhaps another savage pull on the ol' life saver and with no obstructions for the spinning bits they get to live and learn.
an it's lead with throttle and the engine and rotor RPM should stay together there cattletruck, less you have a very worn out set of belts or roll off too much throttle?
HOGE depends entirely on weight, altitude and OAT, recently did an excercise where a Raven I at 2300lbs would have hovered OGE about 300 feet below where it was sitting firmly fixed to the ground only 1200' above sea level.
the old recip rule of thumb was HIGE MAP+ up to 1" running to normal take off, +2" to +3" normal to steep take, I.E. getting up to setting AS for max angle of sustained climb, +4" to +5" perhaps a vertical, slowly.
in fact you should be able translate with just less that 1/2" more than HIGE from the IGE hover. try it, lotsa people have lost a carton of beer at it. keep the bloody stick still, as gordy says.
The 44 should gain an inch of MAP for every 100 lbs that is thrown off, or pick up 100 lbs extra for every 1' spare for the take off required.
possibly none of which applies to this case.
So as a low-time R44 pilot, I'd like to ask a question here. The R44 is capable of an OGE hover at max gross close to sea level. So what are the circumstances that caused him to run out of power? Was it because he was descending fast as he lost ETL? Or what?
Stop a high speed vertical (no or almost no airspeed) descent purely with the collective? See the video...
Try this. Take a can of soup, place it on your right hand, and hold it one inch over the table with your arm fully extended. Easy.
Now, with your left hand, lift the can just one inch and drop it back on your right hand -
See if you can keep your hand from hitting the table. Not so easy. Inertia is a powerful force.
If this quote by the pilot:
While turning to the left in the direction farm road he heard the horn of the main rotor-speed warning and the helicopter lost height. He had the feeling of a " stall without advance warning “.
Thanks everyone for the explanation. Lucky for me (a) I've been taught to be super-careful about VRS and (b) unless there's some dramatic change in my life I'll never be required to land in a tiny clearing at the bottom of a canyon in the middle of a storm, to save someone's life (you can guess how much respect I have for those that do this). But very useful to be aware of!
in fact you should be able translate with just less that 1/2" more than HIGE from the IGE hover.
SE, hover power is take-off power (you don't need to pull pitch to accelerate the aircraft); more is nice to have; less is a serious power limitation.
Power limitation training is great fun but the techniques used should be considered desperate measures and not a way to get around being overweight:-
If you can't manage HIGE, a cushion creep take-off is an option: but you are probably overweight for the conditions and a poorly managed approach may leave you red-faced.
If you haven't got the power to manage a cushion creep you might be able to do a running take-off. But you are asking for it if you do, because you will be seriously power-limited on approach.
In this accident, the pilot probably had enough power to manage the entire flight safely; but appears not to have seen a great big trap staring him in the face.
n5296s you are wise to be wary of VRS; some people seem very vague and receive no training in it at all. Personally, I don't think this accident has jack to do with VRS though.
TT
Last edited by Torquetalk; 18th Dec 2010 at 13:14.
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Love to, of course esp. the R22 and the R44 are a lot easier than where i was doing the challenge which was in the '47. despite my very best effort, i couldn't get away with less than a barely perceptable lever movement and just a smick over 1/4". That's with shiny blades an all.
Harder on the way back as I was lucky enough to always bring home the carton. heh heh. The thing is when moving away from that ground cushion there always seems to be a gap there wider than the vertical distance available to sink, prior to the tentacles of incipient translation. The idea was that sinking was not allowed. A bit of right T/R usually helped to get past the better students.
A carton of beer was after all, a carton of beer.
So, I always make sure the lesson sinks home from the full power configuration on top a vertical if it will, otherwise chuck a bit of gear off, then always go up a margin to trade off a bit of height say 10 ft. above the obstacles (energy) for translation, and slowly does it or you're back in the obstacles eh.
running T/O I found fairly easy to teach, provided the ground was smoth, and the limited power landing was always much easier than that. just an exercise at arriving at nothing with nothing at the right time. all good fun though.
re the downwards interia here is an execise for :--
Google is your friend,
Captain Dodo can help you do that.
But if you add cyclic and depending on the wind direction you can also ask Captain Dodo about these two exercises.
1) Position yourself in a stationary hover in your R44, at say 2100lbs AUW at any height above five hundred AGL will do, AC pointing into a wind of say 5 to 10 knots. Swiftly lower the collective and push the cyclic forward simultaneously to dive off altitude. Keep straight with pedals and maintain RPM in the green.
Now after fifty feet or so or a couple of seconds if you have no visual cues, check back on the cyclic to a level attitude. Manipulate the collective and throttle just enough to maintain RPM in the green without applying too much. At the point which will arrive very soon, where vertical descent ceases, check the MAP, should be about 18” or less. Of course from there one would have to then slowly increase the MAP with collective up to the HOGE power required otherwise the A/C will sink.
2) All OK, now do it again with the A/C pointing in the downwind direction. Now tell us the results. After a coffee when your nerves has settled will be fine. Please don't do it for real outside.
cheers tet.
Harder on the way back as I was lucky enough to always bring home the carton. heh heh. The thing is when moving away from that ground cushion there always seems to be a gap there wider than the vertical distance available to sink, prior to the tentacles of incipient translation. The idea was that sinking was not allowed. A bit of right T/R usually helped to get past the better students.
A carton of beer was after all, a carton of beer.
So, I always make sure the lesson sinks home from the full power configuration on top a vertical if it will, otherwise chuck a bit of gear off, then always go up a margin to trade off a bit of height say 10 ft. above the obstacles (energy) for translation, and slowly does it or you're back in the obstacles eh.
running T/O I found fairly easy to teach, provided the ground was smoth, and the limited power landing was always much easier than that. just an exercise at arriving at nothing with nothing at the right time. all good fun though.
re the downwards interia here is an execise for :--
dodosim?
Hover OGE? yes Stop a high speed vertical (no or almost no airspeed) descent purely with the collective? See the video...
But if you add cyclic and depending on the wind direction you can also ask Captain Dodo about these two exercises.
1) Position yourself in a stationary hover in your R44, at say 2100lbs AUW at any height above five hundred AGL will do, AC pointing into a wind of say 5 to 10 knots. Swiftly lower the collective and push the cyclic forward simultaneously to dive off altitude. Keep straight with pedals and maintain RPM in the green.
Now after fifty feet or so or a couple of seconds if you have no visual cues, check back on the cyclic to a level attitude. Manipulate the collective and throttle just enough to maintain RPM in the green without applying too much. At the point which will arrive very soon, where vertical descent ceases, check the MAP, should be about 18” or less. Of course from there one would have to then slowly increase the MAP with collective up to the HOGE power required otherwise the A/C will sink.
2) All OK, now do it again with the A/C pointing in the downwind direction. Now tell us the results. After a coffee when your nerves has settled will be fine. Please don't do it for real outside.
cheers tet.
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When I was with a company teaching on Robinson's we lost one to over pitching. Lucky for the two guys it was closer to the ground and they survived. The machine was sinking the low RPM horn was on and it just dropped down broke and fell over. It had not been out of its weight limits, density limits or in fact any limit and was mechanically perfect (prior to impact) but still on the face of it the pilot over pitched and crashed.
The cause was tense pilot gripping controls to tight. It was for his level of skill a nervous and challenging landing and in tensing up his grip as he pulled in power near the bottom he over rode the governor preventing it from increasing power. As the horn came on he pulled more power and gripped the lever tighter and the rest was history.
Not saying that this happened in this case simply saying it as a learning point for other newer pilots to learn from. All the calculations about temp, alt weight etc would have changed nothing if the pilot himself is going to limit his power available at an earlier point than the mechanics would.
The cause was tense pilot gripping controls to tight. It was for his level of skill a nervous and challenging landing and in tensing up his grip as he pulled in power near the bottom he over rode the governor preventing it from increasing power. As the horn came on he pulled more power and gripped the lever tighter and the rest was history.
Not saying that this happened in this case simply saying it as a learning point for other newer pilots to learn from. All the calculations about temp, alt weight etc would have changed nothing if the pilot himself is going to limit his power available at an earlier point than the mechanics would.
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disregard the 18" above, for a 540 of course it would be far less, but i would be keen to hear what the sim does.
saw the video of this event for the first time today, and even tho' it's difficult to read the other illustrations help.
It might appear on the face of it that old mate just descended too quickly, maybe or maybe not he saw a bit of VRS.
As far as LTE is concerned I think that's idle dreaming, pilot froze on the controls is much more likely and forgot about the pedals. Real LTE is savage I.E. SAVAGE
Neither does it look like it ran out of Tail Rotor authority, I.E low rpm, the M/R blades are still straight eh! The engine sound seemed all ok normal RPM until the first whack as well. meaning no overpitching recovery action was taken??
by no stretch of the imagination could this picture demonstrate anything but a gentle A/C rotation. I think Sky Bear might be onto it, yep it just fell onto the ground and broke. albeit from a too fast descent indeed almost downwind as well and possibly with the onset of pucker factor.
saw the video of this event for the first time today, and even tho' it's difficult to read the other illustrations help.
It might appear on the face of it that old mate just descended too quickly, maybe or maybe not he saw a bit of VRS.
As far as LTE is concerned I think that's idle dreaming, pilot froze on the controls is much more likely and forgot about the pedals. Real LTE is savage I.E. SAVAGE
Neither does it look like it ran out of Tail Rotor authority, I.E low rpm, the M/R blades are still straight eh! The engine sound seemed all ok normal RPM until the first whack as well. meaning no overpitching recovery action was taken??
by no stretch of the imagination could this picture demonstrate anything but a gentle A/C rotation. I think Sky Bear might be onto it, yep it just fell onto the ground and broke. albeit from a too fast descent indeed almost downwind as well and possibly with the onset of pucker factor.
Real LTE is savage I.E. SAVAGE
Your exercise in transitioning then flaring to the hover into and downwind highlights the nature of flare effect - it is the change in inflow angle that gives the extra rotor thrust into wind - when you are down wind, that change in inflow doesn't happen so no flare effect and an exciting end to the exercise.
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I'm not speculating in what happened, other than the PPL pilot cocked things up from the beginning when he accepted to fly for revenue ..
But would like to point out that the R44 II is no more underpowered in those conditions the crash happened, than many other light turbine helicopters, except if you go well beyond MTOW ..
- madman
But would like to point out that the R44 II is no more underpowered in those conditions the crash happened, than many other light turbine helicopters, except if you go well beyond MTOW ..
- madman
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re: real LTE is SAVAGE
>not when you overpitch gradually as it seems in this case - a gradual reduction in Nr will lead to a gradual reduction in TR thrust and on something as underpowered as a robbie, only a few %Nr can make a large change in TR effectiveness.
I'm curious how much time you have in R44s? Your comment doesn't sound like the R44 at all. Perhaps you're familiar with the R22 and assume the R44 is similar?
First of all, a machine that will climb at 2,000 ft/min isn't what I would consider underpowered. It certainly has as much excess power at MGW as a 206, and the power is there instantly when you need it. Also, at sea level you generally have 2-3" MP past the 5 minute rating (the 5 minute rating is 1.6 past max continuous). There is a lot of excess power available to get you out of trouble - it's very unlike the R22 in that respect.
On the subject of tail rotors, the R44 tail rotor is tremendously powerful; it's happy to hover in a crosswind even at 90% NR. Drooping a few percent isn't going to seriously impact the amount of thrust the tail rotor can generate. Again, not comparable to the R22 in this respect. I can't remember ever hitting the stops on the R44, even doing hover turns on 20G45 days.
I watched the video, agree it was a screwed up approach, but couldn't see enough of the last few seconds to decide for sure why he crashed except probably the reason a lot of helicopters get crashed - stupidity.
I'm curious how much time you have in R44s? Your comment doesn't sound like the R44 at all. Perhaps you're familiar with the R22 and assume the R44 is similar?
First of all, a machine that will climb at 2,000 ft/min isn't what I would consider underpowered. It certainly has as much excess power at MGW as a 206, and the power is there instantly when you need it. Also, at sea level you generally have 2-3" MP past the 5 minute rating (the 5 minute rating is 1.6 past max continuous). There is a lot of excess power available to get you out of trouble - it's very unlike the R22 in that respect.
On the subject of tail rotors, the R44 tail rotor is tremendously powerful; it's happy to hover in a crosswind even at 90% NR. Drooping a few percent isn't going to seriously impact the amount of thrust the tail rotor can generate. Again, not comparable to the R22 in this respect. I can't remember ever hitting the stops on the R44, even doing hover turns on 20G45 days.
I watched the video, agree it was a screwed up approach, but couldn't see enough of the last few seconds to decide for sure why he crashed except probably the reason a lot of helicopters get crashed - stupidity.
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Went and found myself a computer with a much better audio, and for sure one can hear the blades overpitching with Nr running down prior to the sound finishing, almost similar to sound of blades in an auto touchdown.
Regardless as to how good the T/R design is it will lose effectivenss / authority once the Nr winds down too far, that appears to be what happened which can be seen (A/C beginning to rotate) in the video and as Crab says.
The most important factor seems to be stupidity for sure. However it may serve as a good illustration for the adage; Never Descend Downwind, whilst Decreasing Airspeed.
The A/C does not have to enter the magic VRS formula it can simply be placed in the position of not having enough power to arrest the rate of sink set up, and bingo, it damm well falls on the ground and gets all broke up.
The power margin in this case is nowhere near enough to be thought of as enough.
Plenty of blokes have done exactly the same thing in similarly configured '47's or Hillers of identical or more power with far less weight and stuffed up into the ground. 2 - 3 inches spare is bugger all, he could have pulled past the redline (probably did) and it still would have been not enough.
That is one of the problems with Frank's automatic governors, half these dudes don't even know that they have overpitched until the bells start ringing, and then they stuff up.
quite sad, it buggered his whole day.
Never Descend Downwind, whilst Decreasing airspeed. He appeared to be turning into the downwind direction.
The three D's - Drinking - Driving - Death.
Regardless as to how good the T/R design is it will lose effectivenss / authority once the Nr winds down too far, that appears to be what happened which can be seen (A/C beginning to rotate) in the video and as Crab says.
The most important factor seems to be stupidity for sure. However it may serve as a good illustration for the adage; Never Descend Downwind, whilst Decreasing Airspeed.
The A/C does not have to enter the magic VRS formula it can simply be placed in the position of not having enough power to arrest the rate of sink set up, and bingo, it damm well falls on the ground and gets all broke up.
The power margin in this case is nowhere near enough to be thought of as enough.
Plenty of blokes have done exactly the same thing in similarly configured '47's or Hillers of identical or more power with far less weight and stuffed up into the ground. 2 - 3 inches spare is bugger all, he could have pulled past the redline (probably did) and it still would have been not enough.
That is one of the problems with Frank's automatic governors, half these dudes don't even know that they have overpitched until the bells start ringing, and then they stuff up.
quite sad, it buggered his whole day.
Never Descend Downwind, whilst Decreasing airspeed. He appeared to be turning into the downwind direction.
The three D's - Drinking - Driving - Death.