Two dead in Houston helicopter crash
Join Date: Sep 2004
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R22 Crash Houston
Anti - Talk,
Couple your theory, after getting in to "Vortex Ring State" or "Settling with power" as they say in the States and you will not be to far away!
Hot, Heavy and Low!
Couple your theory, after getting in to "Vortex Ring State" or "Settling with power" as they say in the States and you will not be to far away!
Hot, Heavy and Low!
Join Date: Feb 2005
Location: Australia
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A strange kettle of fish and different altogether from the first assumption of a straight and level flight gone wrong.
Now that maneuver is mighty strange but very easy to recover from, just ease forth on the direction meter and up on the feed stick and hey presto, very quickly there is A/S and much less ROD.
Just for something to do while waiting for the ol' bovines to do their bit this arvo i had a go at simulating the description of the two witnesses. I did it in two ways
1) a vertical low power descent with anti-clockwise turn induced with left pedal then centered pedals, it kept rotating and
2) a low power way out of balance slow speed turn (less than 20 knots) to the left with pedals centered.
Power each time around 13" or a bit less, just myself on board (92 kg's) and 80 litres of fuel but a hot afternoon, around 39 degrees Celsius..
In each case recovery was quick and easy, but in both cases more left pedal than was needed seemed to set up a fast even out of control rotation, easily recovered with half right pedal, and or forward cyclic. ROD was at most around 1750 FPM.
As soon as the collective was pulled the anti-clockwise turn ceased abruptly, which I guess is why there is no skewing on the ground spoken about with this accident.
The slowest RRPM I went to was my usual bottom line at 90%.
I think that casual observers suggesting a slow RRPM is a bit far fetched, it's one thing for us guys after thousands of hours picking up a pupe from some distance away in a second helicopter for dropping his RRPM a bit when the pupe is in 47's, but it's entirely another for anyone to discern a fairly slow R22 rotor that is is still flying. I wouldn't pull on that sort of judgement, even the difference between 90 and 110 % is hard to judge by looks, different story with sound though especially an over-speed in an auto.
It may seem there was nothing wrong with the machine, even a T/R failure simulated with three quarter to full right pedal (for clockwise rotation) from around translation or just above, was flown out of easily at around 35 to 40 knots after about one turn with the cyclic forward.
T/R failure from a high hover we used to get weather cocking after one and half turns with , throttle off, collective down and cyclic forward.
Maybe others may wish to try the above steps with a heavier loading on a warm day, but be careful with a bit too much left pedal, the rotation and ROD might get a bit spooky, neither of which was referred to as exceptional by the witnesses.
I would agree with the three previous post as possibles, get a bit of recirculating air and pulled himself into VRS just at the wrong time, or alternatively was descending too low and tried to arrest it too late and over pitched into the ground just before blade stall. Each scenario could give a discerned high ROD for a short time but the VRS one may tend to be more noticeable I think
.( but then an over pitch would have given the slow speed RRPM which the witnesses may remember as being all the time but in fact was impinged on their memory as the last unnatural thing and other emotions may have overtaken their prior recall capacity)
I wonder how old was the pilot, did it have duals and possibly a problem with something lodged into the pedals or collective. 600 hours is not a lot of hours to sort problems, depending on his background, or did he cop an impairment to drive the whole scene, we may never know. I doubt there was a problem with the T/R drive though as if there was a T/R failure surely we would be talking about a clockwise rotation.
cheers tet
Now that maneuver is mighty strange but very easy to recover from, just ease forth on the direction meter and up on the feed stick and hey presto, very quickly there is A/S and much less ROD.
Just for something to do while waiting for the ol' bovines to do their bit this arvo i had a go at simulating the description of the two witnesses. I did it in two ways
1) a vertical low power descent with anti-clockwise turn induced with left pedal then centered pedals, it kept rotating and
2) a low power way out of balance slow speed turn (less than 20 knots) to the left with pedals centered.
Power each time around 13" or a bit less, just myself on board (92 kg's) and 80 litres of fuel but a hot afternoon, around 39 degrees Celsius..
In each case recovery was quick and easy, but in both cases more left pedal than was needed seemed to set up a fast even out of control rotation, easily recovered with half right pedal, and or forward cyclic. ROD was at most around 1750 FPM.
As soon as the collective was pulled the anti-clockwise turn ceased abruptly, which I guess is why there is no skewing on the ground spoken about with this accident.
The slowest RRPM I went to was my usual bottom line at 90%.
I think that casual observers suggesting a slow RRPM is a bit far fetched, it's one thing for us guys after thousands of hours picking up a pupe from some distance away in a second helicopter for dropping his RRPM a bit when the pupe is in 47's, but it's entirely another for anyone to discern a fairly slow R22 rotor that is is still flying. I wouldn't pull on that sort of judgement, even the difference between 90 and 110 % is hard to judge by looks, different story with sound though especially an over-speed in an auto.
It may seem there was nothing wrong with the machine, even a T/R failure simulated with three quarter to full right pedal (for clockwise rotation) from around translation or just above, was flown out of easily at around 35 to 40 knots after about one turn with the cyclic forward.
T/R failure from a high hover we used to get weather cocking after one and half turns with , throttle off, collective down and cyclic forward.
Maybe others may wish to try the above steps with a heavier loading on a warm day, but be careful with a bit too much left pedal, the rotation and ROD might get a bit spooky, neither of which was referred to as exceptional by the witnesses.
I would agree with the three previous post as possibles, get a bit of recirculating air and pulled himself into VRS just at the wrong time, or alternatively was descending too low and tried to arrest it too late and over pitched into the ground just before blade stall. Each scenario could give a discerned high ROD for a short time but the VRS one may tend to be more noticeable I think
.( but then an over pitch would have given the slow speed RRPM which the witnesses may remember as being all the time but in fact was impinged on their memory as the last unnatural thing and other emotions may have overtaken their prior recall capacity)
I wonder how old was the pilot, did it have duals and possibly a problem with something lodged into the pedals or collective. 600 hours is not a lot of hours to sort problems, depending on his background, or did he cop an impairment to drive the whole scene, we may never know. I doubt there was a problem with the T/R drive though as if there was a T/R failure surely we would be talking about a clockwise rotation.
cheers tet
Last edited by topendtorque; 27th Sep 2012 at 12:51.
