Dauphin Crash
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Only one who seems close is old beefer,down in this hemisphere we have managed to scam the whole tape complete with Taiwanese commentary.More importantly the aircraft noise signature is clear throughout the incident.From this one can hear the aircraft arrive happily in the hover complete with its full quota of Nr.Very shortly thereafter there is a failure(probably engine but possibly Fcu)resulting in an audible Nr decay.From the initial failure the aircraft maintained a hover for six seconds prior to loss of tail rotor effectiveness.The rest should be fairly self explanatory.
A good advert for the dauphin if nothing else
A good advert for the dauphin if nothing else
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From the attitude and area of downwash, looked like the ac was coming in downwind. Perhaps too fast, left the application of power/pedal late, lost directionally control/lift, no ground cushion, basically.. *ucked it. Ended up in the drink, thought "Hey everythings still working"
Didn't nb the fact that his Tr was in the wet stuff, and damaged, until he lifted, then it was all too late....
But then that, like everything else on this thread is pure speculation. Look forward to the findings...
Restricted approach direction due to show/film/viewing requirements (ring a bell??)
Didn't nb the fact that his Tr was in the wet stuff, and damaged, until he lifted, then it was all too late....
But then that, like everything else on this thread is pure speculation. Look forward to the findings...
Restricted approach direction due to show/film/viewing requirements (ring a bell??)
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Agree with EEDSL, the pilot definitely cocked it up but why pull it out of the water once he had arrived ‘relatively’ safely??
Can’t agree with oldbeefer on fenestron stall (how's the hand by the way?) – It does not exist, period. I have horsed the old gazelle around more than I ever should have done and there is absolutely nothing wrong with that tail rotor! And if the EC135 has the same back end as the dauphin – there is definitely nothing wrong with that either, as you might well discover MG!
Can’t agree with oldbeefer on fenestron stall (how's the hand by the way?) – It does not exist, period. I have horsed the old gazelle around more than I ever should have done and there is absolutely nothing wrong with that tail rotor! And if the EC135 has the same back end as the dauphin – there is definitely nothing wrong with that either, as you might well discover MG!
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New to this scene but not new to the game.
Whatever caused the descent into the water is irrelevant, isn't it? The problem arises when the apparently inexperienced pilot decides to lift off again. One thing you learn after having taught waterbird for 2 years, is that one NEVER lifts off (either from a dunking or a heavy landing) because as sure as eggs is eggs....that tail rotor shaft/tail cone/tail rotor is not going to do its job again....and with about 4 to 6 G being experienced in the cockpit it's surprising both pilots didn't contact a hard point in the cabin, pass out and drown...lesson learned.
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TC
[This message has been edited by Thomas coupling (edited 16 September 2000).]
Whatever caused the descent into the water is irrelevant, isn't it? The problem arises when the apparently inexperienced pilot decides to lift off again. One thing you learn after having taught waterbird for 2 years, is that one NEVER lifts off (either from a dunking or a heavy landing) because as sure as eggs is eggs....that tail rotor shaft/tail cone/tail rotor is not going to do its job again....and with about 4 to 6 G being experienced in the cockpit it's surprising both pilots didn't contact a hard point in the cabin, pass out and drown...lesson learned.
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TC
[This message has been edited by Thomas coupling (edited 16 September 2000).]
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Those going down the engine failure path, answer this: The a/c yaws to the left before the first impact/touchdown (wrong direction?) and also it is lifted cleanly out of the water for another go. I know that the 76 with arials can't lift the skin off a rice pudding on one engine, so I'd be suprised if the 365 is much better.
Anyone fancy starting a thread on fenestroN stall or otherwise?
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Another day in paradise
Anyone fancy starting a thread on fenestroN stall or otherwise?
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Another day in paradise
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Come on 212,if an engine has failed and the Nr decays on a French heli, it will yaw left, right?! If it then sinks as the Atriel picks up and the mate pulls a handfull of lever, it will leap into the sky as the rotor overpitches 9which will cause the disc to cone up, no?). Ask 24 chopper pilots how to navigate, you'll get at least 45 different answers - ask 24 Gazelle pilots about fenestron stall, you'll get hundreds (and most of them, like purple pitot, will be wrong, right?).....
[This message has been edited by PPRuNe Radar (edited 19 September 2000).]
[This message has been edited by PPRuNe Radar (edited 19 September 2000).]
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Come on, 212man, if an engine fails on a french heli, the a/c will yaw left as the tail rotor Nr reduces no? Yes! If the aircraft then sinks while the Ariel spools up and the pilot grabs a handful of lever, the a/c will eventually lurch skywards with the inertia in the blades, indicated by a greater coning angle - yes? do we really want a discussion on fenestron stall - ask 24 heli pilots how to navigate and you'll get 25 answers. Ask 24 dum de dum about fenestron whatsit and you'll get hundreds. Some of them, like purple pitot, will get it totally wrong! Tried to post something like this just now - didn't seem to work. If you get a duplicate -SORRY
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212 Man,
In a twin engined helicopter unable to hover OEI, following an engine failure where the collective is incorrectly RAISED (or not lowered)in an attempt to prevent descent following an engine failure an OVERPITCHED condition is the result.
Nr then decreases, likewise the tail rotor/fenestron RPM. The torque reaction is still there due to full power on remaining engine. Less effective fenestron due to reduced RPM equals yaw to the left for a French helicopter (main rotor clockwise seen from pilot's seat).
Splash one, with yaw left.
Fenestron drive fails due to overload whilst driving water. Engine then not driving fenestron = more power for main rotor and it may be possible to lift off once Nr recovered.
More yaw left and Splash Two.
(A single engined French helicopter would of course yaw RIGHT following engine failure).
Only problem is, this aircraft did not appear to be overpitched due to its flat coning angle. I would conclude a fenestron problem was the primary factor.
In a twin engined helicopter unable to hover OEI, following an engine failure where the collective is incorrectly RAISED (or not lowered)in an attempt to prevent descent following an engine failure an OVERPITCHED condition is the result.
Nr then decreases, likewise the tail rotor/fenestron RPM. The torque reaction is still there due to full power on remaining engine. Less effective fenestron due to reduced RPM equals yaw to the left for a French helicopter (main rotor clockwise seen from pilot's seat).
Splash one, with yaw left.
Fenestron drive fails due to overload whilst driving water. Engine then not driving fenestron = more power for main rotor and it may be possible to lift off once Nr recovered.
More yaw left and Splash Two.
(A single engined French helicopter would of course yaw RIGHT following engine failure).
Only problem is, this aircraft did not appear to be overpitched due to its flat coning angle. I would conclude a fenestron problem was the primary factor.
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I can see the loss of tail rotor rpm idea up to a point. What I can say from experience is that when I close a throttle on pilots in an american a/c, it yaws left until they compensate with right pedal. The main reason being too much left pedal being applied for the instantaneous torque requirement, along with slow spool up by the 'good' engine. I never let the Nr decay enough to see the yaw reverse, and I have seen 75% Nr both power off and OEI with no problems. In any case, I find it hard to believe that a type would be certificated with such obvious and dramatic side efects following a single engine failure. On top of that, if the Nr was so low to induce loss of TR control, would there really be enough momentum in the main rotors to drag the thing back out of the water into the hover? Anyone due a 365 OPC soon? if so ask to try and establish a hover following a rejected helipad T/O.
Anyway, rather them than me.
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Another day in paradise
[This message has been edited by 212man (edited 19 September 2000).]
Anyway, rather them than me.
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Another day in paradise
[This message has been edited by 212man (edited 19 September 2000).]
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I'm having probs getting this to work. 212man, if a French heli has a single engine failure, it will yaw to the left as the Nr decays. If the mate subsequently pulls in a handfull of lever, as the Ariel spools up it could well leap into the air with an increasing coning angle - couldn't it ? As far as Fenestron Stall is concerned - if you ask 24 heli pilots how to navigate you will get at least 25 answers. if you ask about FS, you will get hundreds of replies - most, like Purple Pitot , will be wrong!
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Still trying to respond to this thread with no luck - try again.....
If a twin has an engine failure in the hover and it's made in France it will yaw left! If the mate then pulls in a handfull of lever as the (other) engine spools up, it will lift to the hover with lodsa coning angle. do we really want to get into discussions on Fenstron stall - likely to get hundreds of answers. Most (like Purple Whatsit) will be wrong!!
If a twin has an engine failure in the hover and it's made in France it will yaw left! If the mate then pulls in a handfull of lever as the (other) engine spools up, it will lift to the hover with lodsa coning angle. do we really want to get into discussions on Fenstron stall - likely to get hundreds of answers. Most (like Purple Whatsit) will be wrong!!
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Oh dear, my head's hurting now (not hard)
Skycop quite rightly says that if a single engine french a/c lose power it will yaw to the right. If a twin engine one lose one engine then you will have a temporary power setting somewhere between that required and zero. However you will still, unless blessed with superhuman reactions, have a pedal position suited to the original power setting ie more right pedal (French still) than is needed for this temporary new power setting. Ergo the a/c will yaw to the right. Now the length of time it takes for the power to be restored will naturally depend on the sophistication of the engines ie Arial with FADEC will respond v. rapidly, PT6 with hydro pneumatic AFCU will take about 4 seconds.
The a/c in question undergoes a steady and pronounced yaw to the left through about 90 degrees before ditching. For this to be due to loss of Nr implies gross overpitching to the extent that an Nr of perhaps 60% was reached. To suggest that sufficient power/Nr was then available to lift the a/c clean out of the water (extra drag doing that as well) is not plausible. A brief lurch maybe, not a fully fledged break dancing display.
Old beefer, your name and location make it obvious you have acces to the odd 412 or two (sorry, Gryphon), have you tried looking at TR response at low Nr? I've had demonstrated to me an OEI take off in the 212 using 'blips' to 70% with no problems. That's 49% of normal TR thrust. I've also tried hovering manouevres myself OEI down to 75% with no ill effects. I still find it hard to believe that the onset of yaw witnessed in the a/c in Taiwan could be solely due to Nr problems. I would support the idea that the subsequent pirroueting (spelling) was caused by post impact TR drive damage.
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Another day in paradise
Skycop quite rightly says that if a single engine french a/c lose power it will yaw to the right. If a twin engine one lose one engine then you will have a temporary power setting somewhere between that required and zero. However you will still, unless blessed with superhuman reactions, have a pedal position suited to the original power setting ie more right pedal (French still) than is needed for this temporary new power setting. Ergo the a/c will yaw to the right. Now the length of time it takes for the power to be restored will naturally depend on the sophistication of the engines ie Arial with FADEC will respond v. rapidly, PT6 with hydro pneumatic AFCU will take about 4 seconds.
The a/c in question undergoes a steady and pronounced yaw to the left through about 90 degrees before ditching. For this to be due to loss of Nr implies gross overpitching to the extent that an Nr of perhaps 60% was reached. To suggest that sufficient power/Nr was then available to lift the a/c clean out of the water (extra drag doing that as well) is not plausible. A brief lurch maybe, not a fully fledged break dancing display.
Old beefer, your name and location make it obvious you have acces to the odd 412 or two (sorry, Gryphon), have you tried looking at TR response at low Nr? I've had demonstrated to me an OEI take off in the 212 using 'blips' to 70% with no problems. That's 49% of normal TR thrust. I've also tried hovering manouevres myself OEI down to 75% with no ill effects. I still find it hard to believe that the onset of yaw witnessed in the a/c in Taiwan could be solely due to Nr problems. I would support the idea that the subsequent pirroueting (spelling) was caused by post impact TR drive damage.
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Another day in paradise
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212 Man,
I think we are talking semantics somewhat as I don't think the video evidence points to simple engine failure, BUT having landed on the water, simply lowering the lever slightly (to below the collective pitch angle causing the overpitching) would allow the Nr to increase rapidly to normal, or perhaps overswing slightly high, bearing in mind that the remaining engine will be at full power. If, as I said last time, the fenestron is no longer absorbing any power it may be quite possible to lift off again, especially as it appeared on the video footage that the aircraft was "caught on the rebound" due to the buoyancy of the hull.
Old Beefer, I think your first posting attempts are actually getting through. There are now two pages on this subject - each time you get "returned to the page" you will actually see the first page and have to scroll forward to the second.
I think we are talking semantics somewhat as I don't think the video evidence points to simple engine failure, BUT having landed on the water, simply lowering the lever slightly (to below the collective pitch angle causing the overpitching) would allow the Nr to increase rapidly to normal, or perhaps overswing slightly high, bearing in mind that the remaining engine will be at full power. If, as I said last time, the fenestron is no longer absorbing any power it may be quite possible to lift off again, especially as it appeared on the video footage that the aircraft was "caught on the rebound" due to the buoyancy of the hull.
Old Beefer, I think your first posting attempts are actually getting through. There are now two pages on this subject - each time you get "returned to the page" you will actually see the first page and have to scroll forward to the second.
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Fenestron stall does not exist! If it did, Eurocopter for one would be out of business a 1000 times over thru criminal damages.
Let's try a change of direction, perhaps....
What is the difference between:
Vortex Ring and Power settling!!!!!
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TC
Let's try a change of direction, perhaps....
What is the difference between:
Vortex Ring and Power settling!!!!!
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TC
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Thank goodness for that, I thought I was going mad.
Tr loses authority for an as yet unexplained reason (but don't mention the S word, and porobably not engine failure), small, thin walled drive shaft does not take kindly to fenestroN (why do they spell it with a capital N?) rotating in treacle rather than air decides to give a Gallic shrug and go on protest (typically Froggish) and poor unsuspecting pilot who now thinks his fenestroN Stall (oops sorry) has stopped retrieves a/c back into hover only to have Newton 3 demonstrated to him in a practical and vivid manner.
Sorted. Back to the tea and biscuits.
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Another day in paradise
Tr loses authority for an as yet unexplained reason (but don't mention the S word, and porobably not engine failure), small, thin walled drive shaft does not take kindly to fenestroN (why do they spell it with a capital N?) rotating in treacle rather than air decides to give a Gallic shrug and go on protest (typically Froggish) and poor unsuspecting pilot who now thinks his fenestroN Stall (oops sorry) has stopped retrieves a/c back into hover only to have Newton 3 demonstrated to him in a practical and vivid manner.
Sorted. Back to the tea and biscuits.
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Another day in paradise