Emergency landing

[rnav44]

If in an emergency close to a airfield one is forced to land what is better, the main runway or the foward speed landing area which is grassy but plain surface.

Which one to choose if adequate length is avaliable on both surfaces???

[evil7]

If you can reach either - always the airport.

Why? Fireservice available:ok:

[rnav44]

what i ment was if iam at the airport.

emergency on board and want to carry out a foward speed landing with an aircraft fitted with skids.

what to do go for runway or grassy patch next to it.

both of the same length and clear of obstructions

[Flyting]

You slide better on tar/concrete

[EN48]

You slide better on tar/concrete

Yes ... but, some runways are grooved (grooves run across the width of the runway) for water dispersion and improved braking for wheeled aircraft. This can be hazardous to skid equipped helicopters especially if one gets a little or a lot sideways. Assuming no acute urgency, I'd probably prefer a smooth (ungrooved) taxiway everything else being equal.

[SilsoeSid]

I would have thought taxiway lighting to be more of an issue than runway grooves and bearing in mind the width differences, surely a runway would be a better choice than a taxiway. Having run 'there and back' along the runway of an international airport during the volcanic ash episode, I would conclude that one must have extremely thin skids for any runway grooving to be considered hazardous. :rolleyes:

[krypton_john]

I've seen slab joints I swear a whole Robinson could fall into, but still preferable to a bumpy grass field.

[MightyGem]

Grass is quieter. :ok:

[Ascend Charlie]

If you land on the grass, you won't have a bunch of jets making expensive diversions because the runway is covered in disabled helicopter.

[Sloppy Link]

Danger of digging in a skid on grass, go for tarmac.

[John Eacott]

Whilst the OP later explains he is referring to a skid helicopter, there are multiple scenarios which could dictate either option.

A skid machine generally has plates under the skid to allow for running along a sealed surface, which can (& does!) leave significant surface damage to a runway seal. Does the emergency landing warrant this?

How large is the helicopter, what is the emergency, how far is it likely to slide? Shortest run-on is likely to be a limited power approach, eg single engine failure on a multi. Longest; maybe a tail rotor failure of some sort. For a short run on then take a firm and level grass and leave the runway clear. Longer run for a T/R failure make a judgement call, but I'd lean toward a runway as a more forgiving surface to an off-centre touchdown.

Then there are the wheeled machines and their foibles, most of which would dictate a better sealed surface.

But as already mentioned, that seal doesn't have to be a runway. It could just as easily be a taxiway or even a clear parking area, especially if there is a significant crosswind on the only available runway. The same holds true of a skid run-on landing on grass, lessening the crosswind issues of going for a seal.

Since the OP is from India there could be further considerations dictated by local norms and requirements?!

Edit to add: never, ever, let the considerations of other operations influence a safety call in an emergency. It should be of no consideration that other serviceable aircraft may need to divert when assessing the safest way of getting yourself and your crew or passengers away from the landed aircraft in one piece.

[helonorth]

I'd always go for the hard surface. No surprises there. The hell with airplanes and their expensive diversions.

[tqmatch]

At least with the hard surface you have less chance of a skid digging in, or the cab bouncing fore & aft possibly causing the trailing blade to contact the tailboom

[paco]

In North America it is routine to do emergency landings on the hard standing, even for practice. Too many potential gopher/rabbit holes in grass. Just be careful about how quickly you put the collective down for the braking action :)

Phil

[BOBAKAT]

In France...Inverse, most of the time, we landing on the grass: is smoothly and so quiet...
I make my first full R44 autorotation in Torrance on the runway. The concrete runway is so noisy.....;)

[Falcon Al]

Each way bet, one skid on the tarmac and one on the field.

[oleary]

ALWAYS choose the hard surface.

Skids: Get sideways in the grass you and might tip over.

Wheels: Same idea.

Wheels on pavement: Nose dragger it will kick straight. Tail dragger you can pedal it straight.

Important thing is, tipping over is much less likely to happen on a hard surface.

And don't worry about grinding the skids (or wheels) - we can always buy new ones :}

[oleary]

Edit to add: never, ever, let the considerations of other operations influence a safety call in an emergency. It should be of no consideration that other serviceable aircraft may need to divert when assessing the safest way of getting yourself and your crew or passengers away from the landed aircraft in one piece.

[John Eacott]

ALWAYS choose the hard surface.

I guess regional outlooks may have overlooked that in many places, eg Australia, the grass usually is a hard surface!

[Wageslave]

ALWAYS choose the hard surface.

Skids: Get sideways in the grass you and might tip over.


Amazing how different countries do the same thing in different ways or have misunderstandings about the "other" way.

In my 4000 odd (european) civ and mil rotary hrs I have never once done a run on landing of any kind on a hard surface on skids, nor heard of anyone that did by choice except in the case of some (but by no means all) tail rotor failures as described by John Eacott. On wheeled aircraft we used the tarmac of course. Can't really imagine why you'd want to wear your skid plates away on a runway or mix it in the circuit with the siezed-wings when you have smooth, slippery grass all to yourself.

Never had any concern about "tipping over" on grass nor felt it likely to happen, largely because it isn't, as millions of European training hours have proved.

[John R81]

Only ever done them onto the grass area at the airfield where I am based. Fastest to date is 50knt (training, tail drive failure).


It occurs to me that there is a big difference between an airfield you know - a surface that you know - and the unknown. I would be more likely to opt for the tarmac / concrete if I did not know for sure that the grass surface was suitable & safe.

[SilsoeSid]

Never had any concern about "tipping over" on grass nor felt it likely to happen, largely because it isn't, as millions of European training hours have proved.

Ignoring of course the times when it has happened :ooh:
(and the many others outside Europe!)


https://assets.digital.cabinet-office.gov.uk/media/5423035640f0b61342000aed/Schweizer_269C-1__G-CCJE_07-06.pdf
Following an uneventful flight, the commander was demonstrating an autorotation to a student PPL who had recently purchased a similar type of helicopter.
He entered the flare with a relatively high rate of descent, which he was unable to arrest by raising the collective lever.

As the helicopter landed, the skids dug in to the relatively soft ground, causing it to roll on to its right side.



… on the other hand;

On May 24, 2011, at 1503 eastern daylight time, a Schweizer 269C, N7505Y, sustained substantial damage during a practice run-on landing at Asheville Regional Airport (AVL), Asheville, North Carolina. The certificated flight instructor (CFI) and private pilot receiving instruction were not injured.

According to the pilot receiving instruction, who was also the owner of the helicopter, the purpose of the flight was to conduct a flight review. Approximately 50 minutes into the flight, the CFI asked the pilot to demonstrate a run-on landing to runway 16. The pilot conducted the approach for landing at about 40 knots and touched down left of the runway centerline on both skids. As he lowered the collective, the helicopter’s right skid contacted a runway centerline light, shearing off the right skid and its support arms.

The pilot raised the collective, picked the helicopter up to a hover and turned towards the taxiway. Shortly after, the engine and rotor RPM began to drop, the pilot opened the throttle and lowered the collective, setting the helicopter on the left skid. The helicopter rolled over and came to rest on its right side, resulting in substantial damage to the main rotor blades.

AOPA Hover Power » Blog Archive » Running landings (http://blog.aopa.org/helicopter/?p=810)



Of course grass can always catch you on take off :eek:

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[EN48]

I would have thought taxiway lighting to be more of an issue than runway grooves and bearing in mind the width differences, surely a runway would be a better choice than a taxiway.

I think its going to depend a great deal on the specifics of a particular situation. Grooved runways are typically found at airports designed to accommodate larger aircraft, with taxiways sized (wider) accordingly. Taxiway lights are often mounted somewhat off the paved surface and with frangible couplings which allow them to easily fold over when struck. If the helicopter is sufficiently out of control to leave the pavement (taxiway or runway) it seems likely that the pilot will be dealing with greater problems than striking an edge light fixture. And, taxiways do not have threshold lights, REIL's, approach lights, touchdown zone lights, centerline lights, localizer antennas, etc, all of which could create challenges under some circumstances.

On a related topic, my favorite instructor is a very high time helicopter pilot with a perfect safety record; what little hair he has left is grey. He considers running landings (in skid equipped helicopters) to be emergency maneuvers whether on pavement or grass, and he will teach them only in a simulated form (low approach at an appropriate speed without skids touching pavement). His view is that too many helos have been rolled into a ball training this maneuver. I am 150% sure that this view will be contested here!

[S70ALM]

Hard surface for all EPs with skids, let skids work (flex) and slide without tripping. Why the concern over fixed wing traffic inconvenience in an emergency?

[SilsoeSid]

Taxiway lights are often mounted somewhat off the paved surface and with frangible couplings which allow them to easily fold over when struck.

Taxiway edge lights may well be off the paved surface, (remembering that they are only required at larger airfields if a taxiway doesn't correspond with the paved surface), but even so, I don't think these edge lights are that helicopter friendly in the 'frangible' department. If edge lighting is used, taxiway centre line lights are still required.

https://upload.wikimedia.org/wikipedia/commons/a/ac/Taxiway-light.jpg

http://www.adb-air.com/media/103/2050_ETES-L_004.jpg

[Spunk]

For training purpose I prefer grass for the very same reasons as mentioned before ( less wear on the skids, less noisy etc).If the grass runway is all muddy (e.g. in winter time) or if there are too many molehills than you better do something else that day.
A prepared grass runway should be as solid and as plain as the paved runway with its expansion gaps. Same applies to the shoulder next to the runway.
However you might want to check whether you are allowed to land next to the runway (for training purpose). In some countries you are not allowed to land next to the runway (might be considered off-airport landing) unless it is an emergency.
In real life I would probably aim for the concrete.

Funny CRM story at the end: spent my vacation in the US and thought it might be a good idea to refresh my FAA license and get my biennial done.
During autorotation I was aiming for the grass whereas my very experienced USCG FI got an increase in heart rate and, by softly pushing the stick with his knee to the opposite side, tried to tell me to go for the concrete. We put the a/c down safely on the grass which made him somehow breathe a sigh of relief.
However he asked me to do the next one to the paved runway.:):)

[EN48]

I don't think these edge lights are that helicopter friendly in the 'frangible' department.

The short taxiway light in your photos does not appear to be of the frangible type. The tall taxiway light has what appears to be a frangible coupling at the base of the post. Hard to tell for sure from the photo.

As stated previously, best choice for landing (if there is indeed a real choice) will depend on circumstances. No single choice will work for every situation.

[Flying Bull]

In case of real emergency - choose an airfield with tarmac- and emergency services!!!!

Remeber a training flight, where I was a passenger (my company check already finished), when the student, lowering the collective on a single engine landing, dug in so deep, that the bouldersteps on the struts moved so far up, that student and instructor couldn´t open the doors to get out.
I could get out the back and after unsrewing the bouldersteps, both could get out.
Or remember the MD crash of the policehelicopter at Hannover, where they had a NOTAR-problem.
All went well, until the helicopter veered to the side of the runway and touched grass.....

So in case the sh.. hits the fan - big airfield!!!!

[Thud_and_Blunder]

My 2 penn'orth:

Middle Eastern state-owned helicopter, skid-equipped, MAUM 2835kg, airport rules only allow approaches/departures to/from prepared surfaces. Quite right under the circumstances - the off-taxiway areas were proper hard-rock desert, and the dust generated on graded surfaces was very damaging to our engines.

Occasion 1 - Precautionary shut-down of no2 engine, night ops, still air, OAT 41 deg Celsius with runway <100ft AMSL. The options are runway (this particular airport has 2), taxiway or apron. Lighting on runway and taxiway are both edge and centreline with poor visual definition in between. Apron is very brightly floodlit, 600m plus clear area. I opted to go for the apron, which the fire crews ensured were clear of people and obstructions. Touched down at the max-allowed (for that type, in those days) 30kts and came to a stop in just under 100m. Very noisy, and the cockpit was very brightly illuminated by the shower of sparks which we were told extended to 3 aircraft lengths and double our height. Skid shoes replaced, suspect engine checked/ repaired and all was well.

Occasion 2 - running landing training, simulated single engine, daytime, OAT around 35 deg Celsius and wind 10 knots or so from 12 o'clock. Student touched down at <30 knots on runway, halfway between edge and centreline as briefed. After gently lowering the lever because it was clear that we weren't decelerating much, I didn't do enough to stop the student drifting toward the centreline. At <10 knots (estimated) we both felt a slight - and I do mean slight - bump before the aircraft came to a halt having travelled some 200m along the runway. Leaving the student at the controls, I climbed out to check the skids - right rear skid post cracked. Embarrassing runway closure for nearly 20 minutes while the heli was recovered. The skid shoe had hit one of the chamfered centreline light housings; even though the latter was only about 2 cm tall, and sloped on all sides, that was enough to break the skid post.

Lessons learned:

If it's a real emergency, go for a hard surface for all the reasons mentioned above. Be prepared - warn the pax and crew - for the very loud noise.

If you want to shorten the run-on, consider a taxiway or apron/ ORP. They have lower construction standards than the main runway, so their friction is greater. I was amazed how much the aircraft slid along the runway surface even with the lever mostly down.

If you're going to do it at night, be prepared for some very bright extra light in addition to the noise.

[SilsoeSid]

There is footage somewhere of a BBC programme covering an event with a very sparky run on by a Lynx. It's out there somewhere ... in the meantime;

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[Wageslave]

Ignoring of course the times when it has happened :ooh:
(and the many others outside Europe!)



Good old Sid.

Never one even to accept the universally established norm that affects his side of the Atlantic when he can quote an exception in a weak attempt to discredit the general with a lone particular, even when the original statement accepted that there were exceptions and made this self-righteous pedanticism quite superfluous. (Sid, nb there's a world of difference between "isn't likely" and "Cannot" or "won't ever". One is an absolute, the other isn't...) Geddit?

[John Eacott]

If you're going to do it at night, be prepared for some very bright extra light in addition to the noise.

My 212 endorsement was done in Tripoli, including night S/E run-ons down the main runway. Lots of bright sparking, and the next day embarrassingly deep grooves in their runway surface.

Thud's dit about using the apron reinforces my earlier advice to look for a hard surface other than the runway, especially if it can provide less of a crosswind :ok:

[SilsoeSid]

Wageslave;(Sid, nb there's a world of difference between "isn't likely" and "Cannot" or "won't ever". One is an absolute, the other isn't...) Geddit?

Maybe so, however you quantified your "not likely", with "millions of European training hours".

As I mention earlier, the instances of rollover during a run on landing are significantly higher on your side of the atlantic, which is probably why you mention 'European' in your statement. :rolleyes:

[Brother]

My old Bell 47 instructor, after an engine off landing where I had made the "spot" by slithering along the grass, said to me:

"Its not the landing that will normally kill you, but the forward speed, so I suggest that you always try to land with the minimum forward speed to reduce the distance it takes you to stop"

I think they were wise words and I have always taken them into account during my 30+ years of flying.

[BOBAKAT]

finally, This is a rhetorical question. Except in training, if in helicopter we have an emergency, we choice the closest and most accessible terrain and then manages.
concrete or grass runway ? .... it is very rare to have a choice in real failure!

Most of the time there is NO runway !;)

[rnav44]

Thank you everyone for their valuable inputs.

A lot has been mentioned on the subject by Shawn Coyle.
Little book of Autorations.

Chapter 11.Pass on the Grass....

Intresting read.

[SilsoeSid]

If it helps, you can read it here;

https://books.google.co.uk/books?id=KW42CgAAQBAJ&pg=PT100&lpg=PT100&dq=shawn+coyle+pass+on+the+grass&source=bl&ots=u0zWvHOzgA&sig=HqnAAX5qUaL09Rls--YYyBsLp0g&hl=en&sa=X&ved=0ahUKEwj1yJKXyrjKAhVE7xQKHQC7BCAQ6AEIITAC#v=onepage&q=shawn%20coyle%20pass%20on%20the%20grass&f=false

[SASless]

When I went through the US Army Helicopter School.....One Skid Length was the maximum acceptable standard for ground slide.

Mind you we did do some the entire length of the heliport when wagering who could slide the longest distance.

But as noted....in helicopters the slower you are at touch down in both vertical and horizontal directions the better off you are.

[bolkow]

lots of passenger terminals have flat roofs? No interferance with other aircraft and you can quickly get down the stairs to the airport bar?

[Lonewolf_50]

:ok:lots of passenger terminals have flat roofs? No interferance wiht other aircraft and you can quickly get down the stairs to the airport bar? Best answer in the thread, when "tongue in cheek" is considered.

[Arnie Madsen]

.

This guy did both .... skids down on grass , then slid across the runway , then back to grass

Had a flameout while doing a maximum performance takeoff .... go to 5:00 in the video

https://www.youtube.com/watch?v=9ltxduwRp_g

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[SilsoeSid]

Have you read the comments on that video?

"Helicyclepilot,You did a great job landing, they don't glide long do they? "
"Awesome piloting! Split second decision making is the trademark of the pros."
"u are your own lifesaver. awesome job"
"Great job man !"
"Great recovery stan!"

What sort of take off was that at 5:25?
Max performance take off you say … I say bollix.

If you're going to do one of those, you sit in the hover and check all is well before undertaking the exercise, not just hoof it all in from MPOG! No wonder it went Pete Tong!

Of course, someone is bound to pipe up now and say, 'Sid, we do things differently over here!'

Oh well, that may well be the case; which is ok if you want to hear of yet another 'brilliant pilot' piling in! But inevitably some would just put that down to bad luck !!!

Oh really :eek:

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[SilsoeSid]

On a more back to thread note:
I'm sure anyone that has visited the EOL area at Wallop would have had the 'little hop over the old track to Knock Wood experience'. :ok:

[Spunk]

But as noted....in helicopters the slower you are at touch down in both vertical and horizontal directions the better off you are.

Especially at night. You don't want to tell the people at the bar that you just made a perfect touchdown into a pitch black hole and then ruined the helicopter by smacking into a tree at 30 kts

[Arnie Madsen]

What sort of take off was that at 5:25?
Max performance take off you say … I say bollix.

If you're going to do one of those, you sit in the hover and check all is well before undertaking the exercise, not just hoof it all in from MPOG! No wonder it went Pete Tong!

Hover check ??? ... he had just landed 5 seconds earlier , everything was working fine , and yes, it was a max/perf takeoff demonstration for a friend at the airport , and that went fine too .... the problem happened after he eased off power the fuel rate dropped too low and caused a flameout ... the idle screw was set too low.

He owns all the land and farm equipment he flies over in the other videos and the long narrow path through the forest leads to the hangar where he built the helicopter . best wishes.

[SilsoeSid]

Hover check ??? ... he had just landed 5 seconds earlier , everything was working fine
'5 seconds earlier everything was fine', however 5 seconds later it wasn't :ugh:
Yea, why bother with checks, just take up valuable time don't they :rolleyes:


"Demonstration for a friend", that 'old gem' and of course; sorry, I forgot that if you own the land below you, it doesn't getcha :ugh:

[krypton_john]

What check would have identified this particular issue?

[SilsoeSid]

Krypton john, you seem to have confused me with someone that cares about what matey boy gets up to.
As long as he doesn't ruin anyone else's life, crack on, I'll look forward to his own thread later.

[krypton_john]

Calm down Sid, it's a serious question. Do you have an answer?

You do seem to care enough to bother making multiple posts here?

[SilsoeSid]

If you care to read my other post, I'll go with Shawn, however as previously mentioned, chances are you won't have much of a choice.

I do however care enough about the dark side of these threads where the actions of some are considered the norm, and those actions are only supported by the impressionable.


The real tale behind the video;

Full down auto from HV curve (http://helicopterforum.verticalreference.com/topic/13910-full-down-auto-from-hv-curve/)

Last Veterans day ....November 11th, I was flying around and decided to go up to the airport. I landed and noticed a friend of mine watching. I decided to show him a very aggressive rate of climb...so I took off and pulled the collective like I had never before.

I am kicking myself as I let euphoria take over common sense. The helicopter was climbing like a homesick angel, when I noticed my rotor rpm's were declining. There isnt a torque meter...or a manifold pressure gauge since its a turbine...and its not necessary to pull a lot of collective...which I did anyway as I was caught up in my dumbass moment. I saw the rotor rpm's down...and dropped collective.

Unfortunately, this caused the turbine's rpm to surge....and it overshot the overspeed limit, shutting the turbine down......flameout! I immediately dropped all the collective and here I was at low airspeed, no more than 100 feet up....and dropping like a rock.

I lowered the nose trying to milk out as much energy as I could. The ground was rushing up...and my only possibility of saving this ship was to do a runon landing at around 40 mph. I landed straight with my flight path which started in the grass on the west side of the runway...then sliding on a diagonal across the asphalt runway...into the grass on the other side before stopping.

I held full collective on the whole ground run on to minimize my decceleration so as to help keep from flipping on my nose. It came to a stop...and I lowered the collective...got out and checked it over. I started the turbine up and all was fine. It was getting dark so I left it in a hanger...checked it over the next morning and flew it back to my shop. I just happened to have had my skid mounted video on...and it was very clear.

If you watch it...the video starts at my shop where I keep the helicopter...then you can see me flying around a farm tractor. I land at the local airport...and at 5:28 I lift off and start doing something I had never done...over torqued the collective.

At 5:42 in the video, you can see a left yaw when my turbine flamed out...and the rest is history. Time came to a crawl. I let euphoria get me into this situation....and I was given the chance to redeem myself by doing what was necessary to hit the tiny keyhole that would save my helicopter.

I have been told that this is probably one of a few if not the only actual video of a real flameout in the HV curve and able to fly it away afterwards.

I am just a fledgling helicopter pilot.....and I learned more in that 10 seconds than any instructor could bark in my ear in a year.

I had the dreaded 3 C's on this flight. Crowd...one is enough.....Camera.....yep ..it was on....confidence....you bet....

Thanks for all the comments. I beat myself about this, and learned a lot. I have an excellent helicopter that I almost destroyed by asking it to do more than it was designed for.

I had a chance to save it though, and I did. I am a fledgling helicopter pilot but having this happen on Veterans day made me feel like maybe I am more of a helicopter pilot now, at least a veteran of having a real auto at a most serious time.

I have over 800 hours in gyroplanes and have had 18 forced landings in them without a scratch. Helicopters are a different animal, and I will be a better pilot by keeping myself at flight speeds and altitudes where another auto will be a lot easier to handle.

[Mars]

NTSB Identification: WPR16LA055

Scheduled 14 CFR Part 135: Air Taxi & Commuter
Accident occurred Sunday, January 17, 2016 in Hanalei, HI
Aircraft: AIRBUS EC130, registration: N11VQ
Injuries: 4 Serious, 3 Minor.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On January 17, 2016, about 1430 Hawaii standard time, an Airbus EC130 T2, N11VQ, landed hard on a beach 2 miles west of Hanalei on the Hawaiian island of Kauai after a reported loss of engine power. The commercial pilot and 2 passengers sustained minor injuries, and 4 passengers were seriously injured. The helicopter sustained substantial damage to the tailboom and airframe. The helicopter was registered to Nevada Helicopter Leasing LLC, operated by Blue Hawaiian Helicopters under the provisions of 14 Code of Federal Regulations, Part 135, and was conducting an air tour flight at the time of the accident. Visual meteorological conditions prevailed for the flight, and a company visual flight plan had been filed. The local flight originated in Lihue at 1406.

The pilot reported that he was about 1/4 mile off shore northwest of Honopu Sea Arch at 1,300 feet mean sea level (msl) when he heard the low rotor rpm aural warning horn. He immediately entered an autorotation and turned towards the beach. He transmitted over the radio that he had an engine failure. As he approached the shoreline he made a right turn to the south and landed hard on the beach. He applied the rotor brake to slow the rotor, and at that time he noted that the engine was not running. The passengers began to exit and he pulled the engine fuel cutoff.

Oh dear, not as easy (in the heat of the moment) as is suggested by some.

[chopjock]

Krypton,
What check would have identified this particular issue?

How about a throttle "chop" from full RRPM before lifting? If the idle stop screw was set too low, this may have revealed it.

[Arnie Madsen]

SilsoeSid '5 seconds earlier everything was fine', however 5 seconds later it wasn't
Yea, why bother with checks, just take up valuable time don't they
A ground check would not have changed anything , see below.

chopjock How about a throttle "chop" from full RRPM before lifting? If the idle stop screw was set too low, this may have revealed it.

Good points but a manual throttle chop would not have shown any problems

The Helicycle uses a belt drive to the 90* gearbox same as R22 & H269

Helicycle belt tension is carefully set so the belts will slip in an overtorque so as not to exceed transmission limitations.

The Helicycle turbine is also set up to prevent overspeed by shutting the fuel to idle via a different control than a throttle chop.

It was this idle screw that was set too low and caused the flameout.

And the only way to find that out was to have an actual overtorque and overspeed. It would not show up in ground checks.

Got to give the guy credit , he built the helicopter himself and it is one of the smoothest machines in the world vibration wise , plus he had a flameout in the dead mans curve and managed to land it without a scratch and flew it home afterwards.

[chopjock]

Arnie
Helicycle belt tension is carefully set so the belts will slip in an overtorque so as not to exceed transmission limitations.

The Helicycle turbine is also set up to prevent overspeed by shutting the fuel to idle via a different control than a throttle chop.

And the only way to find that out was to have an actual overtorque and overspeed. It would not show up in ground checks.

But if "over torque" only causes the belts to slip, then one could overspeed it on the ground checks to confirm fuel shut off to idle is set correctly, right?

[SilsoeSid]

Arnie, two things;

1. Does the Helicylce have a published flight manual or POH? Is there a Performance section/chapter in this POH? Is there an actual HV Diagram?

2. If there is, why does this guy always seem to fly in the right hand part of it?

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[Arnie Madsen]

chopjock But if "over torque" only causes the belts to slip, then one could overspeed it on the ground checks to confirm fuel shut off to idle is set correctly, right?

Yes ... that would seem obvious , but I think an overspeed without load would be using much less fuel than an overspeed under maximum load .... something like that .... a computer makes some fuel-rate decisions in there somewhere , I will ask the owner next time we talk. Thanks.

[Arnie Madsen]

SilsoeSid I dont have time to watch all the videos right now .... the guy is not a crazy cowboy flier , he even cut the path thru the trees in case he had to auto when leaving his yard.

The low mounted camera maybe exaggerates his speed a bit

On that subject , it is an un-stabilized camera stuck to the underbelly ... notice how smooth the machine is ... hard to spot any vibrations at all .

Helicycle has a heavy rotor ala B206 .. lots of inertia for auto.

[Thracian]

This from you:
not a crazy cowboy fliermaximum performance takeoffand this from the pilot himself:
like I had never beforelet euphoria take over common sensesomething I had never done...over torqued the collectiveCrowd...one is enough.....Camera.....yep ..it was on....confidence....you bet....At least at this very flight, he really was a crazy cowboy. And it was of course no "max pwr t/o".
Could call himself lucky to still being able to think about it...

And I will try to not make this error by myself. Although I would not promise it.

Thracian

[nigelh]

I don't see low flying as being in the HV curve and see no problem with his flying ..( other than an over torque if that's what happened )
Also how many people do a power check on every take off even if it's effectively a touch and go ? I think he did a pretty good job !!

[SilsoeSid]

Nigelh;
I don't see low flying as being in the HV curve and see no problem with his flying ..( other than an over torque if that's what happened )
Also how many people do a power check on every take off even if it's effectively a touch and go ? I think he did a pretty good job !!

Can we assume that as an operator of the type(s) mentioned in it, you are aware of Safety Information Notice 2418-S-00 that covers both practises :ooh:
https://www.airbushelicopters.com/website/docs_wsw/pdf/SIN2418-S-00-R0-EN.pdf


I gather you fly/own the 500 and 350, so needless to say you must be familiar with these;

http://i52.photobucket.com/albums/g11/silsoesid/500_zpsnmggkigp.png

http://i52.photobucket.com/albums/g11/silsoesid/350_zpsvxz3ugyt.png


… and for the R22 flyers out there;

http://i52.photobucket.com/albums/g11/silsoesid/r22_zpsdeqqtxbe.png


So, do you still think low flying is not in the curve? :confused:


As for the checks on take off, like clearing turns, maybe for some of us it is habitual to check all is well when lifting into the hover.
:ok:

[chopjock]

Sid,
Interestingly, in your posted copy of the RFM for the H500 Height Velocity Diagram, it doesn't state "HEIGHT", it states on the vertical axis "ALTITUDE ABOVE TERRAIN - FEET"
So what's the difference between this and HEIGHT?
This is a HEIGHT VELOCITY DIAGRAM, not an ALTITUDE VELOCITY DIAGRAM. right?

[SilsoeSid]

Sid,
Interestingly, in your posted copy of the RFM for the H500 Height Velocity Diagram, it doesn't state "HEIGHT", it states on the vertical axis "ALTITUDE ABOVE TERRAIN - FEET"
So what's the difference between this and HEIGHT?
This is a HEIGHT VELOCITY DIAGRAM, not an ALTITUDE VELOCITY DIAGRAM. right?

Chopjock, you do realise on what parameters full size aircraft performance is based on don't you?


… or b.

[nigelh]

Ok ..i accept that low flying may be inside the curve !! Im not sure why , as i would say that engine failure at say 30- 60knots and 10ft was a very easy auto to pull off . I do however accept that a turn to check behind before a towering t/o would be my method !

[chopjock]

Sid
Chopjock, you do realise on what parameters full size aircraft performance is based on don't you?

I was asking if there is any difference between the terms"ALTITUDE ABOVE TERRAIN" and "HEIGHT"
Because I have never heard of the term "ALTITUDE ABOVE TERRAIN" before.

I know the definition of ALTITUDE and HEIGHT, do you have an answer?

[SilsoeSid]

Chop, are you getting confused with elevation?
'Altitude above terrain' is what it says, I can't see what you're missing :confused:

[chopjock]

Sid,
'Altitude above terrain' is what it says, I can't see what you're missing

So if "HEIGHT" is vertical distance above the surface and "ALTITUDE" is vertical distance above mean sea level, what the hell does"ALTITUDE ABOVE TERRAIN" mean?
That's what I am confused about.

[SilsoeSid]

Just to say that I'm not ignoring you chop, still waiting to see if you've worked it out yet :zzz:

[chopjock]

Just to say that I'm not ignoring you chop, still waiting to see if you've worked it out yet

"ALTITUDE ABOVE TERRAIN"

Yes, obviously"ALTITUDE ABOVE TERRAIN" means vertical height above sea level above terrain. LOL

[Thomas coupling]

Ok ..i accept that low flying may be inside the curve !! Im not sure why , as i would say that engine failure at say 30- 60knots and 10ft was a very easy auto to pull off . I do however accept that a turn to check behind before a towering t/o would be my method !

And that's because you don't fully understand the definition of the dead mans curve Nigelh. How can a pilot call himself a professional pilot when he/she doesn't fully understand the dead man's curve??? I find this a common misconception with many civvy pilots. :E

Flying @ 20' 60kts in an MD500 would probably cartwheel an average joe and kill him. Reactions aren't fast enough.
In an R22 - 500' @ 30 kts will probably lead to a collision with the ground by the average abo if he/she doesnt react instinctively with the lever.

Having said that, to be fair, the definition states that the average pilot with average reactions suffering an engine failure inside the HVC will result in probable airframe damage at best, death at worst.
Even twin engine helicopters have HVC's.
Some scarey pilots out there.................................................... :hmm:

[SilsoeSid]

Yes, obviously"ALTITUDE ABOVE TERRAIN" means vertical height above sea level above terrain. LOL

Throwing you a bone choppy;

Answer me this, What are the five different types of 'Altitude'?

[chopjock]

Ok so there's pressure, density,indicated, true and Absolute.
But the height / velocity curve is all about the height and velocity above the surface, right?
I agree if the air is thinner due to high terrain, that should be taken into account, but the graph does not show this.
So my point is the left side of the graph should depict height, as in vertical distance about the surface. So why does it say ALTITUDE? (especially if there are 5 different types!), and yet the Robinson H/V curve is in HEIGHT as it should be.
I guess MD really mean "ABSOLUTE ALTITUDE" instead of the term "HEIGHT"

[SilsoeSid]

Hey choppy; after all that, how is it that you don't have an issue with the term 'velocity'?
:rolleyes:

[chopjock]

how is it that you don't have an issue with the term 'velocity'?

If there were 5 types of "VELOCITY" I might!

[SilsoeSid]

how is it that you don't have an issue with the term 'velocity'?
If there were 5 types of "VELOCITY" I might!

Pity for our listeners that there are only four :ok:

[Thomas coupling]

Choppy babes:

Aviation altitude is measured using either mean sea level (MSL) or local ground level (above ground level, or AGL) as the reference datum.

From wiki for beginners.

Otherwise - I like your determination :D

[nigelh]

TC ..... I thought you were dead !!! I can only imagine that you were a sub standard Mil pilot or that now in your old age your reactions are very slow :rolleyes: If you have actually done throttle chops at v low level you may understand ...... You are aware that when you fly ...you just fly the aircraft and react to changes of pitch etc automatically . You don't actually need to know you have had a failure , no need to drop collective with lightening reflexes . You just flare ....as much as you need to in order to keep height . 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 :eek:

[SilsoeSid]

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 :eek:

Of course we all know that there's no problem flying in 'the shaded areas', much like flying over the sea beside the cliffs … until the donkey stops that is!
That is the moment when the shaded parts of the curve or statements like "within autorotative distance from land" come into play :(

Which is why we will read things in manuals, such as;

Use of Chart:
Caution:
Observe the cross−hatched regions of the Height Velocity Diagram.
These represent airspeed/altitude combinations from which a
successful autorotation landing would be difficult to perform.
Operation within the cross−hatched area is not prohibited, but
should be avoided.


Dance with lady luck too often and eventually she'll step on your toes :ooh:

[nigelh]

Ok fine Sid... So you wouldn't crop spray , sling load , or winch would you ?? I think what you meant to say was that it is not a good idea taking unnecessary risks dallying in the HV curve unless you are doing a job that requires it :ok: Flying outside of auto distance of land is totally different and you should have floats !!

[Arnie Madsen]

.

SilsoeSid ... you remind me of the guy who goes to the airport and opens his hangar door.

The rule books are stacked to the ceiling but there are no aircraft .

.

[SilsoeSid]

Nigelh;
Ok fine Sid... So you wouldn't crop spray , sling load , or winch would you ??

I take it you failed to read the bit of my post that said;
"Of course we all know that there's no problem flying in 'the shaded areas', much like flying over the sea beside the cliffs … until the donkey stops that is!"
p.s. You forgot to mention, low level tactical flying, fast roping, abseiling, fire fighting, lake/river rescue, etc in your list :rolleyes:

Flying outside of auto distance of land is totally different and you should have floats !!
So instead of having a go at certain people here, why don't you get out and spread the word around in your circle of influence?

[SilsoeSid]

Arnie M;
SilsoeSid ... you remind me of the guy who goes to the airport and opens his hangar door.

The rule books are stacked to the ceiling but there are no aircraft

Lol, nice one. Nigel has a similar problem in that when he opens his hangar door he can't get in because the chips on his shoulder are too highly stacked :ok:

[Fark'n'ell]

TC ..... I thought you were dead !!! I can only imagine that you were a sub standard Mil pilot or that now in your old age your reactions are very slow If you have actually done throttle chops at v low level you may understand ...... You are aware that when you fly ...you just fly the aircraft and react to changes of pitch etc automatically . You don't actually need to know you have had a failure , no need to drop collective with lightening reflexes . You just flare ....as much as you need to in order to keep height . 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
:D:D:D:D:D:D:D:D:D:D

[Thomas coupling]

Nigel - my dear old loved one. Many moons ago pprune did this conversation to death. (dead mans curve).
I've carried out well in excess of 2500 autos of which 1500 were engine offs in a single, atleast half were in the 100 - 200' band, many were at low speed, some in excess of 100+ kts.
None were carried out knowingly inside the dead mans curve.
And the reason for that is the military actually pay attention to what the test pilots say when they devise these charts. We 'assume' they are paid to fly the a/c close to the edge and occasionally beyond. We even flew with them on occasion to further understand their reasoning.
Of course civvies don't get these experiences for obvious reasons. Test pilots don't grow on trees. Test pilots don't invent charts like this for a laugh.

This curve advises the operator of the helicopter that given an average pilot on an average day with average reactions in nil wind - should the donk stop, the odds are stacked against him/her and either the helicopter will strike the ground causing damage (heavy landing) and or everything in between up to killing the pilot. Statistics are littered with these results.

There are several operators out there who LIVE inside the HVC. I recall having a conversation with a vet from this industry offline - as a result of our online debate. He has spent most of his professional life living inside the curve. And he is still alive, god bless.

It's not to say that it is a forbidden - no-go zone. It's not to say it will kill you every time, it is suggesting that when the donk stops and the pilot is anything OTHER than sh*t hot - he/she will come a cropper.

Apart from the fact that if an aviation lawyer found out you were operating inside this zone when the lights went out - your claim might look shakey,
people like you must wake up and smell the coffee.

Just because you have flown inside the HVC dozens of times without a mishap, doesn't mean to say you are safe. You are not safe Nigelh please remember that and joking aside - have a long hard think about it when you have a quiet moment (and I know you will). Your bravado about your lightning quick reactions/second nature/instinctive actions will not prevent you from coming a cropper one day - believe me.

For all other civvies who don't court this chart or aren't familiar with the machinations of it. Take a long hard look at the curve - It's NOT mandatory, it is advisory (based on considerable test data and experimentation by people far more capable than you will ever be )look at your flying behaviour and compare. Do you often fly inside the curve (take off, landing and low level) or with just a small tweak to your flight path and speeds - do you fly just outside it.

The difference could mean avoiding a hefty insurance claim or worse still - killing your family if they are onboard when the donk stops and you happen to be inside the curve at the time. Dramatic enough for you!

And please, Nigel those of us who know you, know you are a very capable helicopter pilot - please bear in mind that when you speak on here - some actually listen, so let's cut the crap and provide solid feedback so they can learn from it.:)

[Hughes500]

TC

A superb post but just bear in mind we all have to go into the avoid curve ( dead mans curve, height velocity diagram, call it what you will) for many reasons.
Training for vertical take off and landing for instance with a ppl. Is it unsafe to go into the avoid curve ? Well like everything in life it is down to what we now call threat and error management or what is better called airmanship or perhaps better still common sense. Realistically the pilot is more likely to cock up the landing or take off in a vertical take off scenario than for the engine to actually stop. It is rare these days for engines to stop, biggest reason is running out of fuel !
At work I spend most of my day in the avoid curve lifting with a 50 ft line on the heli. Reason, it is safer for the ground crew and much quicker to hook 6 bags on to a carousel then on to a belly hook, ironically especially if the donk does give up !
I think with the standards of training these days where students aren't even taught to do EOL's to the ground let alone autos from close / inside the avoid curve most have no idea of the threats of operating inside the curve. Thus they don't actually realise the problems they are putting themselves in as they have a " it won't happen to me scenario as my instructor never showed me"
You have had the luxury like some of having had military training, not sure you have experienced the quality of training on the civvy side but I am afraid it can be woeful

[nigelh]

The trouble with you guys , TC and Syd , is that you both come across as being arrogant old farts who who know everything ! I am just trying to redress the balance a little when you come out with statements that come straight from a rule book . As I said earlier , I agree with the sentiment about trying to avoid things such as HV curve but to say " never fly in it " is unrealistic . Which is better when coming into a confined area ....barrelling in at 50knots to stay out of it ...or come to a hover , check power and slowly descend ( which would put you in the curve !) .
I'm sorry Syd if you think that makes me " chippy " .
You guys have a lot of experience between you but both have a very poor bedside manner and that doesn't help get people on your side ..... So how about trying a nicer approach to educate us poor untrained civvies and we may just listen !!

[Soave_Pilot]

I think what comes down to is that if your operation does not require you to be flying inside the shaded área of the HV diagram you shouldn't be there, especially if you are carrying passengers. Every time I find myself flying inside the HV diagram unnecessarily a caution alarm thought goes out in my mind and i fly myself out of there.

[SilsoeSid]

The trouble with you guys , TC and Syd , is that you both come across as being arrogant old farts who who know everything ! I am just trying to redress the balance a little when you come out with statements that come straight from a rule book . As I said earlier , I agree with the sentiment about trying to avoid things such as HV curve but to say " never fly in it " is unrealistic .

Mmmm, another case of not actually reading what someone is posting :rolleyes:

I think you'll find my 'statement straight from the book' was;

"Use of Chart:
Caution:
Observe the cross−hatched regions of the Height Velocity Diagram.
These represent airspeed/altitude combinations from which a
successful autorotation landing would be difficult to perform.
Operation within the cross−hatched area is not prohibited, but
should be avoided."


So, where does it say, 'never fly in it'? :confused:


I think it is quite clear; old farts like TC and myself are only trying to prevent some rotorheads that are reading these posts, from falling into the traps that others don't recognise as traps.

U-turn of the thread;
I don't see low flying as being in the HV curve and see no problem with his flying.

Ok ..i accept that low flying may be inside the curve !!


TC, H500 & S_P put it well :ok:

[EN48]

you both come across as being arrogant old farts who who know
everything !

Nooooo! Cant be! Say it isnt so! ;)

[Thomas coupling]

Nigel you were in grave danger of displaying some rapport there, how dare you :)

3 of my pet subjects are poorly understood by civvy pilots:

The Avoid Curve
Tail rotor failures
Vortex ring state

Forgive me if I am want to impart my experiences coming from a gene pool of probably the best trained helicopter pilots in the world (how is that for arrogance?).
Not only do British military pilots get the best training in the world, they get inputs from manufacturers, test facilities and test pilots that civvy pilots (on the whole) either cannot access or cannot afford.
Mil pilots have access to crash data, simulators and personal experiences that are second to none.
Please dont confuse my experience and flying education as arrogance.
I simply wish to pass onto others what I had - passed onto me when I was going through the learning process, that's all. Light out now, sleep tight, don't let the bed bugs bite xx..................:ok:

[chopjock]

T.c.
3 of my pet subjects are poorly understood by civvy pilots:

I'm a civvy pilot and I understand those 3 pet subjects very well!:)

[EN48]

3 of my pet subjects are poorly understood by civvy pilots:

I am a civvy pilot whose first solo (fixed wing) was in 1966, and have transitioned to helicopters more recently. I dont fly for money, so some here would dismiss me as not being a "professional." However, I go to considerable lengths to live up to the notion of "professional" apart from compensation. One thing I have learned in fifty years of flying is that there is always more to learn. Tail rotor failures and VRS are topics of high current interest for me. I'd welcome any and all links to additional information on these topics. I have found some useful info here using the search function, but this tends to be disjointed and not too portable. Any place this is available in a more organized form?

[nigelh]

TC ( and you Syd !!) .......there is an awful lot that you say that I agree with but what I don't agree with is your method of imparting that knowledge . Your method is to firstly play the military card . ( I have loads of mil pilot friends . Some are useless in the civvy world , some are excellent and I have employed quite a few over the years . On balance I don't see any difference in their ability .) .
Next you try to humiliate people with your view of their lack of knowledge and get personal ...( that's fine with me ...I own my own helicopters and employ people like you and enjoy the banter . Others I fear just get frightened off so are no longer around to pick up your valuable advice )
There are so many gotchas out there ,I think we should concentrate on the big ones ....flying in poor viz leading to CFIT , spacial disorientation , LTE , vortex ring to name a few , these are the things that kill people . I am sorry but flying at 20-30 ft every now and then in an appropriate place is fun , ... We all do it . Every mil pilot I have flown with does it ! I'm not aware that it is inherently dangerous , especially if you know the ground re wires . I am not aware of any crashes involving engine failure while flying at low level . Equally doing a power check on every single approach to hover or land just doesn't happen in the real world ....we all look at our power settings during climb out as standard .
So just pick the things that matter and get people engaged , rather than enraged !! Nite Nite

[Thomas coupling]

All I was trying to do there nigelh was use a bedside manner......you've obviously not been cuddled enough as you missed the hyperbole?
William sends his regards by the way ;)

[SilsoeSid]

Nigel, I have never 'played the military card' on pprune and those that know me will tell you that I don't play that mil/civ game of yours.

As for trying to humiliate people with your view of their lack of knowledge and get personal . I only quote what is said, so if you say something incorrect or simply ridiculous then of course people 'like me' will pick up on it. (thought you said you enjoy the banter) That is how we prevent the unknowing from reading what some say is 'the way we do things' and then going out and killing themselves based on the impression you have given them ... a prime example is included in your last post;

I am sorry but flying at 20-30 ft every now and then in an appropriate place is fun , ... We all do it . Every mil pilot I have flown with does it ! I'm not aware that it is inherently dangerous , especially if you know the ground re wires . I am not aware of any crashes involving engine failure while flying at low level

1. We don't all do it!
2. It's not only wires that will get you!
3. How can you possibly think it's not inherently dangerous!
4. What about the recent Flamborough Head incident with two fatalities!

You seem to have a distorted view of military low flying.
To generalise; Flights were always authorised with an MSD. Very rarely would it be lower than 250' and if on a 'tactical sortie' would 100' Agl/50' MSD for the snurgelling phase. Operationally heights would be 'not above' a specified height for airspace management reasons. So this picture you have of mil helicopters wazzing around at 25' just for the fun if it and because they can, is imaginative at best.

However, I appreciate that doesn't necessarily mean it won't happen, and as I said earlier; dance with Lady Luck too often and she'll step on your toes .... you must remember the Puma at Catterick https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/27119/20111201_redacted_puma_za934_si.pdf

Oh yes;
I own my own helicopters and employ people like you and enjoy the banter .

I wondered when that was going to rear its head again :rolleyes:

[SilsoeSid]

chopjock;
I'm a civvy pilot and I understand those 3 pet subjects very well! :)

Hold on a mo, earlier you said; I agree if the air is thinner due to high terrain, that should be taken into account, but the graph does not show this.

If you understand the subject "very well" you would know that 'The height velocity diagram is based on sea level, standard day conditions, over a smooth hard surface at a specific gross weight.' you would also know that there would be a seperate chart allowing you to 'calculate the reduction in gross weight required as a function of density altitude in order for the Height Velocity curve to apply'.

So why do you say that the graph doesn't take into account "thinner air", or as we would normally refer to it in the aviation industry, density altitude, if you understand it so well?'
:confused:

[nigelh]

Sid ..... This is pointless as you take no notice of what I am saying !! Re read my post and think . I stand by what I say . Flying low level on well known home turf is not " dangerous " . It is totally different to the incident flying en route over the sea ....which IS dangerous !!!! Also your Mil low level is enroute probably over unknown terrain ....wazzing along at 25ft WOULD be dangerous !!! I ask again are you aware of any accident ever happening from engine failure flying low level on home turf over safe flat terrain that you know well ?? I seem to recall loads of quick stops done at 20-30ft with instructors at airfields presumably you have never done that either ??
Bored now , over and out !!

TC . I'm happy with the banter but play nicely !! We are ,after all, all on the same side when it comes to the safety of our fellow pilots . If we really wanted to make a difference we should force the CAA to review their stance on such things as en route ifr without full ifr rating , such as fixed wing IMC . Mandatory instrument training in actual IMC , even if just for 1 hr to experience first hand disorientation . Synthetic vision , affordable autopilots etc etc etc But nothing has been done to address this over the last 30 years !!!

[SilsoeSid]

I stand by what I say . Flying low level on well known home turf is not " dangerous " .

I ask again are you aware of any accident ever happening from engine failure flying low level on home turf over safe flat terrain that you know well ??

Does the Norfolk Pavehawk crash count? Oh and the Coln McRae crash report makes good reading on this topic.

And there's this;
"Although the pilot was familiar with the airstrip and was aware of the location of the powerlines, research by the ATSB has shown that an awareness of powerline location does not guarantee avoidance."
http://www.havarikommissionen.dk/images/Bibliotek_luftfart/General_Aviation/Low_level_flying.pdf

You seem fixated on the only danger being wires or engine failures, there are many other factors that are out there just waiting for you, such as;

Agusta A109C, N109TK
Near Kew Bridge.
While cruising at 150 kt at 750 ft agl a bird struck and shattered the left windshield. The commander, seated in the left seat, suffered minor injuries so the co-pilot took control and made a successful emergency landing.


Aerospatiale/Westland SA 341G Gazelle
Location:Rudding Park
Summary:
The pilot, was undertaking a helicopter flight with a passenger, in gusty wind conditions. He was seen flying slowly, at a low level, near a chalet he owned in the grounds of an hotel when the aircraft was seen to spin around, before pitching up and falling to the ground, fatally injuring the two occupants.

[[email protected]]

Perhaps 'dangerous' is too emotive and vague a term to be bandied around in this context - branding something simply as 'dangerous' or 'safe' is too binary when we all know there is a sliding scale of risk attached to aviation (as in most things in life).

So if you start with the premise that all aviation activities carry risk - which we make strident efforts to minimise through training, regulation, engineering practices etc - it is clear that some of those activities will carry additional risk.

Is flying close to the ground inherently 'dangerous'? clearly not becuase it is happening around the world all the time. Does it carry extra risk? Most certainly, or we would all be smashing around at 5' and 140 kts because that would be lots of fun.

However, most of us want to go home to our wives and family at the end of the day so such additional risks as wirestrike, inadvertant contact with the ground, birdstike, catastrophic mechanical failure (including engine failure) are taken into consideration and the sliding scale of risk (in this case lower and faster) is modified by our willingness to take on that extra risk and our reasons for doing so.

The message really is - can you fly inside the H-V curve? Yes.

Should you fly inside the H-V curve and how far into it do you go? Providing you have understood the additional risks and have a good reason for doing so then how far you push is a matter for a good risk vs reward assessment.

The danger is that pilots often have a greatly over-inflated opinion of their ability, especially in dealing with rapidly changing and dynamic situations and that is where people get suckered into the 'I can do this, I'm a great pilot' which can often become 'I've been doing this for years and it's been fine' right up to the point where it isn't.

The Colin Macrae incident is a case in point - over confidence and a history of showboating isn't a good recipe for safe low flying.

[500e]

Crab good post, danger has levels you draw a line for your self as long as it does not impinge on others.

"Is flying close to the ground inherently 'dangerous'? clearly not because it is happening around the world all the time. Does it carry extra risk? Most certainly, or we would all be smashing around at 5' and 140 kts because that would be lots of fun.

However, most of us want to go home to our wives and family at the end of the day so such additional risks as wirestrike, inadvertent contact with the ground, birdstike, catastrophic mechanical failure (including engine failure) are taken into consideration and the sliding scale of risk (in this case lower and faster) is modified by our willingness to take on that extra risk and our reasons for doing so."

[nigelh]

Good sensible post Crab , all of which I pretty much agree with !
However we were talking specifically about the avoid curve and specifically about engine failures . 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 !!

[[email protected]]

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:ok:

[Thomas coupling]

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?:ugh:

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).:eek:

[Torquetalk]

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

[SilsoeSid]

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 :eek:
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 !!

Now, let's just put those two together and show some 'results';

HeliHub 18-Aug-15 N5743W Bell 206 Cresco, US-Iowa (http://helihub.com/2015/08/18/18-aug-15-n5743w-bell-206-cresco-us-iowa/)
HeliHub 24-Jul-15 C-FRAP Robinson R44 Strathroy, Canada (http://helihub.com/2015/07/24/24-jul-15-c-frap-robinson-r44-strathroy-canada/)
HeliHub 28-Mar-15 N130HA Hiller UH-12E Fresno, US-California (http://helihub.com/2015/03/28/28-mar-15-n130ha-hiller-uh-12e-fresno-us-california/)
Helicopter spraying pesticides crashes near Gonzales | Local News - Home (http://m.ksbw.com/news/helicopter-spraying-pesticides-crashes-near-gonzales/21326742)
http://www.witness.co.za/index.php?showcontent&global%5B_id%5D=94307
HeliHub 30-Aug-12 F-GHYS Agusta-Bell 47G-2 Ajoupa-Bouillon, Martinique (http://helihub.com/2012/08/30/30-aug-12-f-ghys-agusta-bell-47g-2-ajoupa-bouillon-martinique/)
Helicopter Loses Power, Pilot Lands in Burbank Orchard (http://www.kvewtv.com/article/2012/may/30/helicopter-loses-power-pilot-lands-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).

[[email protected]]

Asphalt will also likely give you more ground effect at the bottom in a marginal situation. Hmmmm - care to explain that one? I'm sure Nick Lappos' urban myths covered that topic some while ago.

[Torquetalk]

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

[Thomas coupling]

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 :sad: And if you continue with that frame of mind..........in time, you will stoof.

[[email protected]]

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:ok: Wonder if the insurers coughed up!

[SilsoeSid]

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 :ok:

http://www.pprune.org/rotorheads/483614-top-world-photos-nepal-175.html#post9255491

[nigelh]

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 .

[[email protected]]

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.:ok:

[nigelh]

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 !!

[Thomas coupling]

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.

[[email protected]]

People far more clever than me demonstrated this to me when crop spraying If they were that clever they probably wouldn't be crop dusting for a living;)

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:ok:

[krypton_john]

"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!

[[email protected]]

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?

[chopjock]

crab
would you trust a bunch of test pilots who have actually tested that outcome
Is this where you got the "wait 1 to 2 seconds from"?

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.

If so I don't much trust the test pilots who think I would wait for that long to react!

[krypton_john]

R22 PPL students are certainly quicker than that!

[[email protected]]

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.

[EN48]

It really isn't rocket science.

You wouldnt know that in light of some of the posts here.

Amazed that this horse is still kicking almost seven pages in!

[SilsoeSid]

It really isn't rocket science.
You wouldnt know that in light of some of the posts here.


Isn't it ....

lwNQf08Kxsw

[Torquetalk]

"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."


Well Crab, the short answer to that is no.


Mind you, I have been attempting to get a bit of project off the ground that may shed a bit of light on the matter and have approached Wimbledon and Lords about using their well-mown surfaces to measrue some solid run-ons. Still waiting for a reply there. But I have had an intruiging offer from Aintree saying I could take part in an event involving a variety of terrain, namely grass; asphalt; hedge row(!) and even water. To be honest, I got the impression that someone was sending me on a bit of a wild steeple chase.


In the meantine, I will have to concede that I haven't got a jot of evidence. Somewhere in there is the thinking (righlty or wrongly) that above grass the laminar flow will be more disturbed, and that even if tarmac is the higher friction surface, this "stickiness" will occur very close to the surface allowing a more laminar flow to develop almost immedeatly above.


Point taken about temperature differences. Late morining with a baking hot sun on the asphalt there might be some pretty thin air above the runway. Maybe that adjacent grass strip in the shade deserves a second look after all.


TT

[krypton_john]

TT, if you would like the ultimate in large, smooth and firm grass areas to test run-ons, I suggest you contact the greenkeeper at the Old Course, Royal and Ancient Golf Club of St Andrews! :)

[Torquetalk]

Ta John!


Letter in the post.


I see it all unfolding clearly: the high speed run-on; the "favourable" gradient; that ever-so-low drag coeffient: "Is it a birdy? is it a plane?


TT

[[email protected]]

TT - having done some interesting run-ons teaching student instructors on EOLs- - I can tell you that when going from grass to tarmac and back to grass again (that was the runway crossing) the tarmac was definitely the grippiest on the skids:ok: .......I think we are going lonnnnnnggggggg...

Maybe a bunker with some sand might have been useful.............engine off golf - now there's an idea;)

[MightyGem]

Amazed that this horse is still kicking almost seven pages in!
Well, you know what they say about horses and water. :)

[Hughes500]

Crab
Sorry it's late as on holiday in South Africa but and it is a big but you certainly know if the donkey has given up in a piston engine as the machine has yawed by about 45 to 90 degrees in a split second ! Seeing as many are taught on Pistons there reaction is qued by this rapid yawning with punching the lever down. So your assertion that they don't know what is going on is false. Now in a turbine that would be true. I do throttle chops in both types, all pilots react quicker in a piston because of its reaction probably just as well as most don't have a high inertia head. In a 300 at 60 it's , auto speed 48 kts snap the throttle and the rrpm is off the green with a yaw of about 45 degrees. By the time the lever is down.Thankfully this type really drops its nose with the lever down so easy to restore rrpm. Part of the lesson though is to always try and fly above best auto speed so you have energy to play with. Back to the pool now. Although my only engine failure was at 80 ft and about 35 knots,just bent the rear cross beam

[[email protected]]

Hughes - hope you enjoy your hols:ok:

Do you ever do throttle chops when the student is in the middle of changing a frequency or squawk or has a map in his hand?

That is a real-world scenario rather than a pre-meditated training one and the reaction will be a lot slower.

[RVDT]

Hughes500,

Don't get lulled into turbines being slow to decelerate in a real engine failure.

Closing the throttle on a serviceable turbine when it is running is only showing you the FCU decal rate that it can achieve without flaming out!!

When they stop for real its a bit more interesting!

PS How many of you RR A250 operators do regular decal checks just to be sure?

[Hughes500]

RVDT

Bit difficult to actually do anything else in training as I am sure if engine seized the result would be the same as a piston ! Never had the turbine donkey go in flight had one shut down as we pulled pitch to go to hover but again it was a run down as there was contamination in fcu filter.
Crab you are quite right do try and chop throttle at inconvenient times. Only once stopped the engine for real. In a 300 have to hold the throttle against the "Spring" otherwise as you pull full lever at bottom the correlation gives you about 2200 rpm.Student did a throttle chop as pre take off check all was ok until I throttle chopped it over the airfield downwind at 500 ft to find to my horror the engine stopped. The student very Cooley said you have control !big lesson to instructor try it from your side as well !
As for the holiday now in Addo, just love walking in to see elephants, and be Jesus was the big bull big, puts a new meaning on things when on foot