Helicopter down in Madrid (1st Dec.)
It's funny to listen to some of you inexperienced and uneducated mother hens out there, squawking, "RAWWK, RAWWK, LTE, LTE!" every time a Bell goes down.
LTE had nothing to do with this accident.
Nothing. Repeat after me. Nothing. So get off it.
The problem was much more basic than that.
As the "pilot" pulls his overloaded, overgrossed (no matter what he says) TwinRanger up to an OGE hover, you can hear the poor engines topping out with the resultant decay of RPM, both engine and rotor. As he tries to get over the stands, things are going very badly. His MR and TR RPM are now so low that directional control is lost and the ship yaws to the right...just as any other helicopter on the face of the planet would do (given a rotor with the same direction of rotation, of course). Down he goes! Ironically, he crashes into an area presumably large for such an operation at that weight, had he chosen it instead of the confined area.
I don't see conspiracies everywhere, I don't see little green aliens, and I don't see LTE as a contributing cause of *every* Bell accident. Some of you really take the cake!
LTE, indeed.
LTE had nothing to do with this accident.
Nothing. Repeat after me. Nothing. So get off it.
The problem was much more basic than that.
As the "pilot" pulls his overloaded, overgrossed (no matter what he says) TwinRanger up to an OGE hover, you can hear the poor engines topping out with the resultant decay of RPM, both engine and rotor. As he tries to get over the stands, things are going very badly. His MR and TR RPM are now so low that directional control is lost and the ship yaws to the right...just as any other helicopter on the face of the planet would do (given a rotor with the same direction of rotation, of course). Down he goes! Ironically, he crashes into an area presumably large for such an operation at that weight, had he chosen it instead of the confined area.
I don't see conspiracies everywhere, I don't see little green aliens, and I don't see LTE as a contributing cause of *every* Bell accident. Some of you really take the cake!
LTE, indeed.
PruneFan:
What makes you think that in a normal HEALTHY helo [one which has a greater buffer before entering its LTE envelope] in the SAME SCENARIO, there would have been an Nr drop, a slight counter yaw .....and nothing else of signifigance. The pilot in the 'normal' helo would then have checked down on the collective, possibly missing the stands maintaining fwd 'controlled' flt. It is abundantly clear on the video that he enters a sharp defined and rapid counter yaw - that sonny, is the LTE kicking in.
[I'm not saying that would have mitigated his choice of LZ in the first place, but he could have escaped with his pants on fire IF, repeat IF he hadn't entered LTE...it was this that finished him off.
Argue otherwise????????????????
What makes you think that in a normal HEALTHY helo [one which has a greater buffer before entering its LTE envelope] in the SAME SCENARIO, there would have been an Nr drop, a slight counter yaw .....and nothing else of signifigance. The pilot in the 'normal' helo would then have checked down on the collective, possibly missing the stands maintaining fwd 'controlled' flt. It is abundantly clear on the video that he enters a sharp defined and rapid counter yaw - that sonny, is the LTE kicking in.
[I'm not saying that would have mitigated his choice of LZ in the first place, but he could have escaped with his pants on fire IF, repeat IF he hadn't entered LTE...it was this that finished him off.
Argue otherwise????????????????
Last edited by Heliport; 5th Dec 2005 at 07:56.
Sorry PPRUNE FAN#1 but I am confused!
You start by saying - "LTE had nothing to do with this accident"
Then say - "TR RPM are now so low that directional control is lost"
What is the difference between LTE and loss of directional control due to low RPM?
I have no problem with Bell products and used to fly the 206 series quite happily (and would again if asked!) but I can't see any major difference between your understanding of the event and that of others!
TeeS
You start by saying - "LTE had nothing to do with this accident"
Then say - "TR RPM are now so low that directional control is lost"
What is the difference between LTE and loss of directional control due to low RPM?
I have no problem with Bell products and used to fly the 206 series quite happily (and would again if asked!) but I can't see any major difference between your understanding of the event and that of others!
TeeS
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Tees
LTE is normally taken to be a loss of tail rotor authority due to stalling at normal operating RPM's as opposed to PF1's suggestion that the tail rotor lost authority is due to a slowing of the RPM.
If you listen to the sounds in the clip you can clearly hear the slow down as the pilot attempts to climb over the stands overpitching. As the main and tail rotor system (squared) slows down the effect of the tail rotor is lost allowing the aircraft to begin to spin.
Must say that having seen LTE in a 500 when the tail rotor stalls it is the same as removing it from the aircraft and that baby will start to spin pretty damn quick. Loss due to slowing down though is slower to take effect and this is shown in the way the aircraft is only rotating slowly to the right.
Would have to agree with PF1 on this unless of course the pilot had lost power for some reason though did not hear any horns on the inside shot I saw. Still sure it will all come out in the report in due time whoever is right, main thing is all survived to tell the tale.
P.S. just to throw a spanner in the works maybe the pilot was yawing right on purpose to try and increase the main RRPM and clear the stands??? Oh where do I collect my wooden spoon!
LTE is normally taken to be a loss of tail rotor authority due to stalling at normal operating RPM's as opposed to PF1's suggestion that the tail rotor lost authority is due to a slowing of the RPM.
If you listen to the sounds in the clip you can clearly hear the slow down as the pilot attempts to climb over the stands overpitching. As the main and tail rotor system (squared) slows down the effect of the tail rotor is lost allowing the aircraft to begin to spin.
Must say that having seen LTE in a 500 when the tail rotor stalls it is the same as removing it from the aircraft and that baby will start to spin pretty damn quick. Loss due to slowing down though is slower to take effect and this is shown in the way the aircraft is only rotating slowly to the right.
Would have to agree with PF1 on this unless of course the pilot had lost power for some reason though did not hear any horns on the inside shot I saw. Still sure it will all come out in the report in due time whoever is right, main thing is all survived to tell the tale.
P.S. just to throw a spanner in the works maybe the pilot was yawing right on purpose to try and increase the main RRPM and clear the stands??? Oh where do I collect my wooden spoon!
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Watching both videos and assuming no mechanical failure it seems like a pretty simple accident to avoid. A vertical take off would have allowed the pilot to pick the wind and get it on his nose before trying to get airspeed. If he didn't have the power to tower out he could have descended back to his original spot and unloaded some bums. And from a spot like that if he didn't have the power to tower out there was probably no way he was going to have the power for the any other type of departure either. If you have any doubts about power in a tight area I never move off my spot until I am above the obstacles...well above.
Just a question for bell drivers... What sort of torque must he have been pulling in that aircraft to get an rpm droop like that ???? I have seen 206s spiked but I've never heard one drop rpm like that ???? 115%, 120% ????? any ideas ???
Just a question for bell drivers... What sort of torque must he have been pulling in that aircraft to get an rpm droop like that ???? I have seen 206s spiked but I've never heard one drop rpm like that ???? 115%, 120% ????? any ideas ???
Overpitched' Good question!
I have myself been to 110% Q on the "L" model without experiencing any RPM drop and a colleague had a 123% Q overtorque (UMS fitted) to avoid obstacle and he said he never experienced loss of RPM and the UMS agreed, it showed a momentarily decreaso to 98% Nr and the RPM was actually back up to 100% +-0.8% by the time he reached 123% torque.
The helicopter was a 206L with Allison 250 C30 engine.
Nedless to say it had to have complete inspection and overhaul to its rotating components and was out of service for 3 months but at least he didn´t crash it.
Someone above mentioned that the pilot may have on purpose let the helicopter spin to the right. That is an often used procedure on the 206L to avoid overtorque so I agree that it may have been on purpose and the aircraft may have been experiencing a power failure or power loss i.e. stuck PC valve or similar problem where you dont really hear the turbine winding down or engine out warning.
I have myself been to 110% Q on the "L" model without experiencing any RPM drop and a colleague had a 123% Q overtorque (UMS fitted) to avoid obstacle and he said he never experienced loss of RPM and the UMS agreed, it showed a momentarily decreaso to 98% Nr and the RPM was actually back up to 100% +-0.8% by the time he reached 123% torque.
The helicopter was a 206L with Allison 250 C30 engine.
Nedless to say it had to have complete inspection and overhaul to its rotating components and was out of service for 3 months but at least he didn´t crash it.
Someone above mentioned that the pilot may have on purpose let the helicopter spin to the right. That is an often used procedure on the 206L to avoid overtorque so I agree that it may have been on purpose and the aircraft may have been experiencing a power failure or power loss i.e. stuck PC valve or similar problem where you dont really hear the turbine winding down or engine out warning.
Agree with Max takeoff and overpitched. Climbing vertically would have told you if this departure was going to work. Backing up and having a "run" at it is being a Gambler. I wonder what the AU weight was before take-off.
I would be interested to know what tail-rotor this L4T was fitted with, the High-altitude or standard tail-rotor. The High-altitude one sucks alot of power. Anyone in the know?
I would be interested to know what tail-rotor this L4T was fitted with, the High-altitude or standard tail-rotor. The High-altitude one sucks alot of power. Anyone in the know?
From inside:
http://www.apythel.org/exterior/acci...les-EC-HCT.wmv
More
Video: http://www.elpais.es/multimedia/play...lpepunac_1.Ves
Video:
http://www.elmundo.es/documentos/200...ero/index.html
Photos:
http://www.elmundo.es/albumes/2005/1...efe/index.html
Do you all agree with this procedure??¿¿
I don\'t like how it sounds.. but what do I know
Regards.
Aser
http://www.apythel.org/exterior/acci...les-EC-HCT.wmv
More
Video: http://www.elpais.es/multimedia/play...lpepunac_1.Ves
Video:
http://www.elmundo.es/documentos/200...ero/index.html
Photos:
http://www.elmundo.es/albumes/2005/1...efe/index.html
Someone above mentioned that the pilot may have on purpose let the helicopter spin to the right. That is an often used procedure on the 206L to avoid overtorque
I don\'t like how it sounds.. but what do I know
Regards.
Aser
