Emergency landing
Nigel, I'd be surprised if there were many (if any) instances where an engine failure or similar (belt fail on a Robbie perhaps) at low level has been the cause of an accident (fatal or not). Most low-level accidents are attributable to CFIT or, more usually, wires.
However, ignoring the H-V curve is fraught with danger and pilots must be aware of the extra risks involved when operating inside it. Chopjock's assertion that the flare will give you time to sort things out ignores the reality of the time it takes to recognise the failure and take corrective action, especially at speeds where there is little flare effect - say 60 kts and below - to save your backside.
Your best option for a succesful EOL is to be into wind, wings level, at your recommended autorotation speed with the minimum RoD possible and over a flat and level piece of ground suitable for the manoeuvre (or in the low hover). That doesn't mean to say you won't survive if those parameters aren't met but the further you are from them, the less and less likely even a gifted pilot is to be able to walk away.
If you are habitually operating outside those conditions then you would be very stupid not to recognise that you have ratcheted up the risk significantly both from the position and the extended exposure. Again, this isn't a problem if you are cognisant of the risk and try to mitigate it where possible.
The German Air Force used to teach pilots to raise the lever before flaring in the Huey in the event of an engine failure at very low level (NOE) to avoid smashing the tail in and making things worse. But that was in a very high inertia rotor system and the same technique in, say, an R22 wouldn't be appropriate as you would be counting the Nr in single figures very quickly.
Bottom line - the H-V curve is there for good reason - your safety
However, ignoring the H-V curve is fraught with danger and pilots must be aware of the extra risks involved when operating inside it. Chopjock's assertion that the flare will give you time to sort things out ignores the reality of the time it takes to recognise the failure and take corrective action, especially at speeds where there is little flare effect - say 60 kts and below - to save your backside.
Your best option for a succesful EOL is to be into wind, wings level, at your recommended autorotation speed with the minimum RoD possible and over a flat and level piece of ground suitable for the manoeuvre (or in the low hover). That doesn't mean to say you won't survive if those parameters aren't met but the further you are from them, the less and less likely even a gifted pilot is to be able to walk away.
If you are habitually operating outside those conditions then you would be very stupid not to recognise that you have ratcheted up the risk significantly both from the position and the extended exposure. Again, this isn't a problem if you are cognisant of the risk and try to mitigate it where possible.
The German Air Force used to teach pilots to raise the lever before flaring in the Huey in the event of an engine failure at very low level (NOE) to avoid smashing the tail in and making things worse. But that was in a very high inertia rotor system and the same technique in, say, an R22 wouldn't be appropriate as you would be counting the Nr in single figures very quickly.
Bottom line - the H-V curve is there for good reason - your safety
Nigelh: best we all write to QinetiQ now then and the ETPS etc and tell them they are talking bollocks as there is no hard evidence that what thye have discovered is true, eh?
Knowing Silsoe - he is probably trawling the global search engine for low level engine failures in helicopters.
Please, please tell me you either accept the HVC for its credibility, or you totally ignore it because there is no evidence lying around?
Do you apply this way of thinking to the moon landing, or to the fact that the strathclyde helicopter may have been inside the HVC when it all went quiet?
C'mon Nigel - your chance to stand up and be counted as apro - do you believe what is stated about the HVC and promote it or do you tell everyone it's a myth? No harm will come to pilots (honest).
Knowing Silsoe - he is probably trawling the global search engine for low level engine failures in helicopters.
Please, please tell me you either accept the HVC for its credibility, or you totally ignore it because there is no evidence lying around?
Do you apply this way of thinking to the moon landing, or to the fact that the strathclyde helicopter may have been inside the HVC when it all went quiet?
C'mon Nigel - your chance to stand up and be counted as apro - do you believe what is stated about the HVC and promote it or do you tell everyone it's a myth? No harm will come to pilots (honest).
Gentlemen, it seems that only handbags at dawn will settle this. So will you meet on the asphalt or the grass?
i've long been persuaded by the asphalt camp, but it is surprising how dominant training cultures can be in creating an [almost] entire nation of pilots who will choose one over the other without really paying much attention to why.
One colleague missed the field during a night auto in the sim, by a mile or two, and justified the landing foray into the blackness with the grass preference argument. Yeah right.
Asphalt will also likely give you more ground effect at the bottom in a marginal situation.
Landing on a big runway in a small helicopter (and without rad alt) can make judging the flare height difficult. I'd go for a taxiway or apron, as someone else mentioned.
TT
i've long been persuaded by the asphalt camp, but it is surprising how dominant training cultures can be in creating an [almost] entire nation of pilots who will choose one over the other without really paying much attention to why.
One colleague missed the field during a night auto in the sim, by a mile or two, and justified the landing foray into the blackness with the grass preference argument. Yeah right.
Asphalt will also likely give you more ground effect at the bottom in a marginal situation.
Landing on a big runway in a small helicopter (and without rad alt) can make judging the flare height difficult. I'd go for a taxiway or apron, as someone else mentioned.
TT
Purveyor of Egg Liqueur to Lucifer
Nigelh;
TC .....
If you would like a lesson from me I'm quite happy to teach you . Off course being a military God you probably never did crop dusting and never learnt the art of really low level . The crop dusting pilots on here could teach you a few things about HV curve and what's possible as they are flying in it all day long
TC .....
If you would like a lesson from me I'm quite happy to teach you . Off course being a military God you probably never did crop dusting and never learnt the art of really low level . The crop dusting pilots on here could teach you a few things about HV curve and what's possible as they are flying in it all day long
Sid has STILL not come up with any evidence of any crash ( there must be one over the last 30 years as its so dangerous ...!!) that is relevant to v low flying engine failures .
I made it clear as day that wazzing around hitting wires / trees / losing control were not relevant !!! If he can't find a few accidents directly due to low level engine failures within the avoid curve then I think it's fair to say that it's not inherently dangerous !!
I made it clear as day that wazzing around hitting wires / trees / losing control were not relevant !!! If he can't find a few accidents directly due to low level engine failures within the avoid curve then I think it's fair to say that it's not inherently dangerous !!
HeliHub 18-Aug-15 N5743W Bell 206 Cresco, US-Iowa
HeliHub 24-Jul-15 C-FRAP Robinson R44 Strathroy, Canada
HeliHub 28-Mar-15 N130HA Hiller UH-12E Fresno, US-California
Helicopter spraying pesticides crashes near Gonzales | Local News - Home
http://www.witness.co.za/index.php?s...5B_id%5D=94307
HeliHub 30-Aug-12 F-GHYS Agusta-Bell 47G-2 Ajoupa-Bouillon, Martinique
Helicopter Loses Power, Pilot Lands in Burbank Orchard
What surprises me most though, is that Nigel hasn't heard of this one;
Hughes 269C
Owner/operator: Thirsk Aero Services Ltd
Registration: G-BKJR
C/n / msn: 44-0299
Fatalities: Fatalities: 0 / Occupants: 1
Other fatalities: 0
Airplane damage: Written off (damaged beyond repair)
Location: Sower Hill Farm, near Catterick, North Yorkshire - United Kingdom
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature: Agricultural
Departure airport: Felixkirk Airfield, Thirsk, North Yorkshire
Destination airport:
Narrative:
ENGINE FAILURE WHILE CROP SPRAYING AT SOWER HILL FARM, NEAR CATTERICK, NORTH YORKSHIRE ON 13-07-1984
THE AIRCRAFT WAS CROP SPRAYING AT A HEIGHT OF ABOUT 4 FEET ABOVE THE GROUND. WHILE IN A TURN IT SUFFERED A PARTIAL POWER FAILURE AND THE PILOT WAS UNABLE TO MAINTAIN FLIGHT. ON IMPACT IT ROLLED ONTO ITS SIDE AND THE MAIN ROTOR BLADES HIT THE GROUND. (AIB BULLETIN 11/84).
Asphalt will also likely give you more ground effect at the bottom in a marginal situation.
Well, if you're sceptical Crab and Nick Lappos has dispelled the idea, then perhaps I'll be revising my thoughts there anon. But they currently go something like this:
In presenting a lower friction surface, asphalt will give a better inflow to the rotor and result in a bigger angle of attack for the same pitch position. The effect may not have time to develop, given rate of descent, flare height, the rapid transition from flare to settling and pulling pitch. But if there is a floating element to the end of the auto, I would hazard it could make its presence felt and help mitigate a bad outcome. A marginal aid to help save the day.
When trying to land with rotton right TR problems, more ground effect from asphalt will reduce the power requirement, and a lower pitch position is clearly more of what you want as you look for the right constellation to run on.
TT
In presenting a lower friction surface, asphalt will give a better inflow to the rotor and result in a bigger angle of attack for the same pitch position. The effect may not have time to develop, given rate of descent, flare height, the rapid transition from flare to settling and pulling pitch. But if there is a floating element to the end of the auto, I would hazard it could make its presence felt and help mitigate a bad outcome. A marginal aid to help save the day.
When trying to land with rotton right TR problems, more ground effect from asphalt will reduce the power requirement, and a lower pitch position is clearly more of what you want as you look for the right constellation to run on.
TT
Nigelh - I did warn you about threatening Silsoe like that - he is loathe to let go until he gets to the bottom of anything and your jibe about showing us all where these accidents are.....well you didnt just shoot yourself in the foot, you damn well blew your leg off.
But of course what that exercise of yours taught me (yet again) is that there are people out there just like you, who never ever think it will happen to them, even when they taunt others about accident statistics - they don't believe they exist, they don't beileve in anything other than their capabilities.
Unfortunately nigelh...and you'll have to sit down for this one:
YOU ARE HUMAN, just like the rest of us. You will react just like the rest of us, when the donk stops in the HVC you will come a cropper just like the rest of us. You aren't in the mil - consider yourself lucky, because the mil have an extra word in their vocabulary and it's called ATTRITION. And if you are ordered to carry out low level in the HVC manouevres - you do it come what may.
Civvies have the luxury of ignoring that and staying safer and possibly living longer.
PS: No amount of money makes a pilot safer or braver - remember that.
Sorry 'mate' you're just NORMAL
And if you continue with that frame of mind..........in time, you will stoof.
But of course what that exercise of yours taught me (yet again) is that there are people out there just like you, who never ever think it will happen to them, even when they taunt others about accident statistics - they don't believe they exist, they don't beileve in anything other than their capabilities.
Unfortunately nigelh...and you'll have to sit down for this one:
YOU ARE HUMAN, just like the rest of us. You will react just like the rest of us, when the donk stops in the HVC you will come a cropper just like the rest of us. You aren't in the mil - consider yourself lucky, because the mil have an extra word in their vocabulary and it's called ATTRITION. And if you are ordered to carry out low level in the HVC manouevres - you do it come what may.
Civvies have the luxury of ignoring that and staying safer and possibly living longer.
PS: No amount of money makes a pilot safer or braver - remember that.
Sorry 'mate' you're just NORMAL
And if you continue with that frame of mind..........in time, you will stoof.
TT - any scientific basis for the assumed difference in coefficient of friction between asphalt and grass? Any factor applied for the lentgh of the grass? Or the temperatures of the surfaces? Runways and roads seem to be designed to have a high coefficient of friction rather than a low one.
Whilst the proximity of the ground does affect the inflow angle I'm not sure that the friction (or lack of it) of the surface makes any difference to that.
I have heard many theories about how the type of surface affects the power required to hover but, other than recirculation, have never been able to measure any difference whatsoever and certainly none I would rely on in an emergency above and beyond that which the simple ground effect does bestow.
Nigel - as previously mentioned, operating in the HV curve and suffering an engine failure might not kill you but none of those events Sid has linked to have left the aircraft in any vague semblance of serviceability Wonder if the insurers coughed up!
Whilst the proximity of the ground does affect the inflow angle I'm not sure that the friction (or lack of it) of the surface makes any difference to that.
I have heard many theories about how the type of surface affects the power required to hover but, other than recirculation, have never been able to measure any difference whatsoever and certainly none I would rely on in an emergency above and beyond that which the simple ground effect does bestow.
Nigel - as previously mentioned, operating in the HV curve and suffering an engine failure might not kill you but none of those events Sid has linked to have left the aircraft in any vague semblance of serviceability
Wonder if the insurers coughed up!
Purveyor of Egg Liqueur to Lucifer
nigelh; I'm sure like all of us here you have a lot of respect and admiration for Vertical Freedom. May I suggest that you look at his most recent pictures (1st Feb) taken during his instructor renewal, and observe what he has written at the bottom right of the whiteboard shown in the second picture
http://www.pprune.org/rotorheads/483...ml#post9255491
http://www.pprune.org/rotorheads/483...ml#post9255491
I hate to disappoint you two but I don't think you make a case . 5 or 6 accidents over nearly 40 years almost all without injury ......AND you had to troll around at spraying accidents which I'm afraid are not the same . We were talking about flying 20-30ft over known good terrain ( which is what that guy was doing ) ..... Not flying 4ft above the ground in a fully MAUW crop sprayer with huge booms out each side flying often over very difficult terrain !!
So we still , over 40 years , cannot find loads of incidents where people have crashed and/or been hurt . I don't advocate blindly flying in the curve , in many instances a decent landing would be impossible ( say hovering downwind at 100ft for instance ) . I have now spoken to my best flying gurus and all of them agree with my stance . There are so many daft things people do and you have to pick on the most innocuous of the lot !! You keep bringing up instances of flying that were definitely not safe .... And I agree with you . I will not however agree that low level flying ( not 4ft or 6ft ...but for sake of argument 20-40 ft and 50-70 knots ). I think we should just agree to disagree on this one ....and like you TC , I have done loads of EOL from exactly this configuration ... I don't think I will be needing a new leg just yet !!
Ps. TC Why no reply to the points about real safety issues in areas that WILL kill you ....such as degrading viz , 180 instrument turns , spatial disorientation etc Surely these areas are far more important than this nonsense about flying at 30ft !!!! I can assure you we can find loads of instances where people have died in these scenarios and we don't even need Sid to go back 40 years .
So we still , over 40 years , cannot find loads of incidents where people have crashed and/or been hurt . I don't advocate blindly flying in the curve , in many instances a decent landing would be impossible ( say hovering downwind at 100ft for instance ) . I have now spoken to my best flying gurus and all of them agree with my stance . There are so many daft things people do and you have to pick on the most innocuous of the lot !! You keep bringing up instances of flying that were definitely not safe .... And I agree with you . I will not however agree that low level flying ( not 4ft or 6ft ...but for sake of argument 20-40 ft and 50-70 knots ). I think we should just agree to disagree on this one ....and like you TC , I have done loads of EOL from exactly this configuration ... I don't think I will be needing a new leg just yet !!
Ps. TC Why no reply to the points about real safety issues in areas that WILL kill you ....such as degrading viz , 180 instrument turns , spatial disorientation etc Surely these areas are far more important than this nonsense about flying at 30ft !!!! I can assure you we can find loads of instances where people have died in these scenarios and we don't even need Sid to go back 40 years .
Last edited by nigelh; 3rd Feb 2016 at 13:27.
Nigel, you do ignore the very obvious element in your 'safe EOLs' from 20-40' and 50 - 70 kts - you know it is coming.
Next time, close the throttle and wait 1 to 2 seconds before taking any recovery action - that will accurately simulate a real pilot's reaction time.
Will you die? probably not. Will you bend the aircraft? very probably - see the links from Sid for the pictures.
Yes, there are lots of other stupid things that pilots do and lots more 'dangerous' situations but this discussion has focussed on operating in the H-V curve and it is certainly not as 'safe' as you believe.
In the end it is your 'Ass, tin, ticket' (to quote Sasless) that is on the line so it is up to you but don't try to sell it to others as good and acceptable practice.
Next time, close the throttle and wait 1 to 2 seconds before taking any recovery action - that will accurately simulate a real pilot's reaction time.
Will you die? probably not. Will you bend the aircraft? very probably - see the links from Sid for the pictures.
Yes, there are lots of other stupid things that pilots do and lots more 'dangerous' situations but this discussion has focussed on operating in the H-V curve and it is certainly not as 'safe' as you believe.
In the end it is your 'Ass, tin, ticket' (to quote Sasless) that is on the line so it is up to you but don't try to sell it to others as good and acceptable practice.
My final word .....!!! I agree 90% with you Crab . I never said it was as safe as flying high ..of course there is some reduction in overall safety . Is it dangerous , especially if flown by a competent pilot , No . Lastly the reaction to a power failure is very different to high altitude failure . When close to the ground your flare reaction will be the correct reaction just in the same way as if you hit a gust or shear . You are not reacting to the failure , and possibly may not have recognised it , but you will automatically maintain altitude in that split second .
People far more clever than me demonstrated this to me when crop spraying ...believe or don't believe !! If you are so concerned about safety ,why not get an answer to why we have done nothing about the real killer over the last 40 years . The same one that fixed wing have all but eradicated !!
People far more clever than me demonstrated this to me when crop spraying ...believe or don't believe !! If you are so concerned about safety ,why not get an answer to why we have done nothing about the real killer over the last 40 years . The same one that fixed wing have all but eradicated !!
Nigelh - you sure about the final word?
When your only donk stops, no amount of flaring will keep it airborne. She will eventually make contact with terra firma. AND if you are inside the HVC when it happens - and you react as joe average acts, you will either hit the ground fast or hard or both. All of which will almost certainly cause damage or death or both.
Do not dispute this - this is fact according to test pilots, not crop dusters.......perleeeeeze.
Nigelh - are you really sure about the last word.........................................
If you really want to talk about your other issues - start a new thread. We've totally hijacked this - apologies to the OP.
When your only donk stops, no amount of flaring will keep it airborne. She will eventually make contact with terra firma. AND if you are inside the HVC when it happens - and you react as joe average acts, you will either hit the ground fast or hard or both. All of which will almost certainly cause damage or death or both.
Do not dispute this - this is fact according to test pilots, not crop dusters.......perleeeeeze.
Nigelh - are you really sure about the last word.........................................
If you really want to talk about your other issues - start a new thread. We've totally hijacked this - apologies to the OP.
People far more clever than me demonstrated this to me when crop spraying
As TC points out, no-one is making this stuff up, it is the result of empirical testing by some very skilled pilots - believe or don't believe
"If they were that clever they probably wouldn't be crop dusting for a living"
Crab, that comment could be interpreted by some as showing you as an arrogant snob. Say it ain't so!
Crab, that comment could be interpreted by some as showing you as an arrogant snob. Say it ain't so!
KJ - it ain't so - my point is that if you want the real ideas about the likely outcome of an engine failure at low level, would you trust a bunch of test pilots who have actually tested that outcome or a bunch of ordinary pilots who kid themselves their job isn't dangerous?
Join Date: Nov 2008
Location: UK
Age: 66
Posts: 919
Likes: 0
Received 0 Likes
on
0 Posts
crab
Is this where you got the "wait 1 to 2 seconds from"?
If so I don't much trust the test pilots who think I would wait for that long to react!
would you trust a bunch of test pilots who have actually tested that outcome
Next time, close the throttle and wait 1 to 2 seconds before taking any recovery action - that will accurately simulate a real pilot's reaction time.
The aircraft are certified under these conditions - 1 second delay for civil and 2 second delay for military.
Of course students are quick - they know it is coming.
You guys need to stop deluding yourselves about your reaction time to an engine failure when you are busy flying and trying to complete a task.
The first thing you will probably notice is a change in noise, long before your brain has started to process loss of Nr - even though it is happening quickly from the point of failure.
You might react automatically to a slight reduction in height - especially at low level where your cues are very good - and will probably react by raising the lever because you haven't realised why you are descending - there goes some more Nr.
By the time you actually diagnose the failure and react to it, the Nr is decaying rapidly and you are already moving further from the point where you can make a safe EOL. Any flare might help to recover the Nr but it isn't going to stop you descending unless you are plus of about 100 kts.
If you are very low level, your flare may well smack the tail in - adding to your problems.
It really isn't rocket science.
Of course students are quick - they know it is coming.
You guys need to stop deluding yourselves about your reaction time to an engine failure when you are busy flying and trying to complete a task.
The first thing you will probably notice is a change in noise, long before your brain has started to process loss of Nr - even though it is happening quickly from the point of failure.
You might react automatically to a slight reduction in height - especially at low level where your cues are very good - and will probably react by raising the lever because you haven't realised why you are descending - there goes some more Nr.
By the time you actually diagnose the failure and react to it, the Nr is decaying rapidly and you are already moving further from the point where you can make a safe EOL. Any flare might help to recover the Nr but it isn't going to stop you descending unless you are plus of about 100 kts.
If you are very low level, your flare may well smack the tail in - adding to your problems.
It really isn't rocket science.