Video from cockpit-R44 crash

[Aser]

1B3aUWSG0KE

:=

Regards
Aser

[stringfellow]

any thoughts??? seemed to have little airspeed at impact?????

[FH1100 Pilot]

Well this one's easy. I know it's kind of stating the obvious, but...

Flying along kind of low, brought the a/c to an OGE hover. Started settling vertically, maybe even a little backward, had lots of power pulled. Let's see, what happens when we do a vertical descent with power pulled? What's that condition called again? I forget...

Anyway, he must've kept pulling because the low-rotor horn sounds and continues to impact. Manifold pressure gauge is up at 29", tach needles are pointing straight at each other. Not good! He must've tried to fly out of it because at :14 we see he's got the nose down 12 degrees or so and has started to get some airspeed back. Too little, too late...crunch.

Textbook settling with power. Or, as Nick likes to say, settling with insufficient power. If only Frankie had put a dang turbo on that 540! If only...

[mickjoebill]

Glad they made it out.
Fearing its demise even the video camera had flashbacks.

Wonder if pilot inputs were governed by the video cameraman.


Mickjoebill

[kanetoads]

Well it's one thing to settle with power in a R44, it's another to do it in a $50 million dollar stealth chopper in Pakistan.

I guess it can happen to the best of them.

[Could be the last?]

Kanet,

Apples and pears!!

[HeliCraig]

I'm sure I'll be castigated for asking this, but if I can get something of an answer / better understanding in the mean time, great, so here goes:

The video does indeed look like settling with power... can anyone resolve this apparent conflict for me (my highlighting):

1. In the R44 PoH, Emergency Procedures, Low RPM horn it states:
To restore RPM, immediately roll throttle on, lower collective and, in forward flight, apply aft cyclic.

2. In the R22 Flight Training Guide (RHC publication), Maneuver Guides, Settling with Power, it states:
To recover, apply forward cyclic to increase airspeed and simultaneously reduce the collective.

I suspect I am blurring the line between Settling with Power and the Low RPM horn... but can anyone help me understand why?? Am I right in thinking the settling with power occurred first (obviously), and if identified could be be resolved as per 2. If it develops into low RRPM then 1 must be used??

I must be missing something. :rolleyes: :bored:

[Sky Bear]

Hi Helicraig,

No such thing as a stupid question so don't worry about that here.

The low RRPM horn action you mention from the handbook is correct especially when you have forward speed.

Roll on throttle to increase engine output
Lower lever to reduce pitch and drag to also help increase RRPM
The aft cyclic input is to increase disc loading which will bring up the RRPM

The disadvantage of a low inertia rotor system is that you can drop rotor RPM quickly however the opposite is also true in that you can recover it again fairly quickly especially by loading the disc. Hopefully this should be shown by all instructors and covered in the further effects of controls also.

In the case of Vortex ring/settling with power you will probably not have much airspeed as this forms one of the three factors required

Low airspeed indicated, high rate of descent and power applied. You therefore need to remove one of these three to recover hence the forward cyclic to gain airspeed. Unfortunately this normally happens close to the ground on approach or photo sorties when orbiting a scene and the resulting height loss can be exciting to disastrous.

With the advent of governors in even the piston market now I fear that not enough is understood by new pilots of energy conservation and management with regard to the rotor system. Probably one of the most important aspects of flying our chosen helicopter and very much so when the donkey quits.

Ask an instructor who understands such things (they all should) to talk it through with you and fly it also if you want.

[SFHawk]

In No.1 it states that "if in forward flight" apply aft cyclic. This is to use some of your positive airspeed to "load the disc" by gently flaring and increasing rotor rpm.

If you are settling with power (No.2), you do not have any airspeed to trade, you may be going forward if you have a tailwind, but it is positive airspeed you need to recover hence forward cyclic.

I think No.1 is referring to a situation when in forward flight without enough engine rpm to maintain rotor rpm (maybe at manifold limits, too heavy, overiding govener etc.), hence low rpm horn. But not referring to settling with power.

Please feel free to pick holes in these explanations as it will only improve my knowledge as well.

SFHawk

Beat me to it Sky Bear! Good to know you can get speedy responses, I'll learn to type more quickly!

[biggestboy]

can anyone shed any light on why there is subliminal flashing of boats on a lake during the crash video???

[9Aplus]

My estimation from rich related experience is that: During impact camera was
under high G therefore some part of mechanical tape transport was not performing
well enough. Tape was not new, re-used, old taping of boats was bellow and tape
was not traveling close enough to recording head during few critical seconds...

[topendtorque]

An unblievably stupid sequence. The after crash picture shows that before flight a set of scales perhaps could have been used for seat maximum weight.

At about the four to five second mark the MAP and RPM flash past. MAP at about 18". Needles joined and somewhere fairly high.

Definately cannot be power settling of any sort so i disagree with FH1100 pilot there. He appears to have put the lever down, the engine noise is consistant and healthy to this point. Also it can be seen then that the aircraft is descending which it wouldn't for a short time at least, had he kept the lever up and simply rolled off throttle.

I suspect he entered auto to be a flash harry for a movie star youtube appearance with a zero speed auto and stuffed it is my opinion. Note the high nose angle at the four second low power mark.

Note also no violent yaw at entry, ol' mate was possibly prepared for this maneuvre to a small extent.

Had the engine quit we would have heard it and quite possibly heard also a vocal exclamation of surprise of some sort as well as a yaw.

Before the MAP disappeared at about 7.5 seconds it can be clearly seen fluctuating up to nearly 19' then back down, like - uh oh first pull way too high there Einstein.- still at about 250'.

Then next we saw the MAP at about 12 seconds its at the top of the gauge, don't worry about where the red line is back aways, still now at about fifty feet - according to altimeter and outside reference.

Did I say a bit high for pulling collective?

Ol mate has pulled it right up at around the nine second mark it looks like somewhere above fifty feet.

1.At that point the ROD slowed and pegged at about 500 FPM but didn't get time to show the higher ROD closer to the ground.

2. The altimeter also had time to stabilise at fifty feet and was still reading that at very close to the ground as ROD built up.

3. Needles at 50' were already at 80 to 82%. Onset of rotor stall here. At 14 seconds it clearly looks like a faster closure rate with the ground from somewhere around twenty to fifteen feet.

The real ROD at impact was just slow enough with just enough forward airspeed to take just enough bounce out of it to be survivable.

Had the aircraft been at Max AUW it certainly would have been a different story for those onboard or if the final pull to full power been another four to ten feet higher.

The Main Rotor blades demonstrate bending consistant with rotor blade stall.

The question remains unsolved, why have a very low power setting at normal RRPM at about 300' with a deliberate very high nose attiutude and a normal sounding engine?

Tingles run up and down my spine thinking about it.

[lelebebbel]

The question remains unsolved, why have a very low power setting at normal RRPM at about 300' with a deliberate very high nose attiutude and a normal sounding engine?

Because he did a quick stop flare? I think FH1100 has it spot on. IMO, that was an attempted quick stop to OGE hover, except the pilot is too late, and then too abrupt with the collective. He's got the collective close to the floor during the flare. When the airspeed is gone and he finally starts raising the lever, the helicopter is already descending vertical + backwards. Now engine power alone is insufficient to stop the momentum -> overpitch (full throttle, 29" MAP).
The recovery attempt in the end (nose down) is too little, too late.


The MAP tells us that he couldn't have been much higher than sea level. I bet with smoother control inputs, that machine would have hovered OGE there just fine.

[FH1100 Pilot]

can anyone shed any light on why there is subliminal flashing of boats on a lake during the crash video???

We talk about people in dire situations seeing their lives flash before their eyes. In this instance I think the camera was seeing its life flash before its lens.

[Thomas coupling]

Definitely not power settling. He brings the cab into a downwind hover (watch the fireman hosing it down after, fire crews always aim the foam downwind(given the choice) which is the same direction the helo is lying, so assuming he didnt yaw prior to landing he's downwind. The cab initiates a "fast" stop, then descends because he doesn't pull enough power and you have the classic symtoms of incipient vortex ring. Not enough height for fully developed VR, hence only a reasonable but unacceptable rate of descent on landing.

[Torquetalk]

TC

..but he is clearly overpitched, incipient VRS doesn't require this. Are you suggesting he overpitched as part of the consequences of ivrs?

The low pitch position and MAP value may have contributed by driving his RRPM down due to over-function of the correlator in this range. Don't want to be sinking with no airspeed at that point.

R44 overpitch accidents are like buses: there'll be another one along in a minute. Perpetuated rubbish about loads of power probably contributes.

TT

[FH1100 Pilot]

Guys, we must remember that SWP and VRS can be two separate things. Nick stresses this over and over. In my opinion, this one was absolutely (lack of) power-settling and not VRS. Yes, we see him start a vertical descent, but almost immediately he gets the horn so we know the rpm was dropping. Why? Most certainly because the engine fell off the power curve and could not maintain RRPM given the collective pitch demand no matter how far open the throttle was (and apparently it was opened all the way).

I suspect that if the poor, overworked 540 in that machine had more power, he would have been able to maintain his RRPM and salvage what was obviously an ill-conceived and executed manuever. (Or maybe it would have progressed into VRS anyway...who knows?)

And I also agree with whoever said that the R-44 pilot was lucky that he performed such a stunt at a low altitude. If he'd had another couple of hundred feet I'm sure he would've gotten the rotor to stall and the resulting rate of descent would've been much higher (and probably fatal). Lucky, lucky pilot. Bad pilot, but lucky pilot.

Finally, in the after-crash footage it appears that the tailboom is broken. In crash sequences, when a main rotor blade strikes the tailboom, the helicopter often rotates before coming to rest. Sadly, do not ask me how I know this. So the way he was heading when he first got into trouble is really no guarantee that the ship will end up on that same heading after the crash.

[Aser]

This is exactly the reason I opened a new thread, instead of using the videos thread... the same old debate about SWP/VRS. :}

Thomas coupling and topendtorque, you'll pay the next round of beers.

You can see the flare (the nose goes up+low MAP) for the quick stop/hover (even going backwards), overpitching => crash.

To me is settling with (lack) of power

Regards
Aser

[Thomas coupling]

Aser: I can only base it on what I see from the limited video.

Torquetalk:I bow to your knowledge re: r22/44 and overpitching etc, but SWP is an engine performance phenomenon and VRS is an aerodynamic state. I see:
a fast stop and flare, I see possible downwind, I see a descent developing and I then suspect an overpitch whilst trying to arrest the descent.
If it can be substantiated that he was heavily laden, this could lead to SWP, but assuming normal AUM, then I wager IVRS.

FH1100 pilot: Your comments on his state of sexual arousal have no bearing :D

"but almost immediately he gets the horn"....:eek:

[FH1100 Pilot]

Thomas, imagine this scenario - and it is not too farfetched:

Our intrepid pilot is cruising along into the wind at what looks to be about 300' agl. For some reason he honks the nose up and zeros the airspeed. But...oops! Too far up and the helicopter starts translating backward with the wind and begins settling as well. Now stuff starts happening fast! But maybe Mr. Peter Pilot is as much behind the power curve as his engine is about to be. He does not want to hit the ground backing up so to arrest the descent he pulls in all the power...and maybe even a little more...and the rotor rpm starts drooping. Mr. Pilot realizes that he better get some airspeed, quick! so he drops the nose. But dangit, the RRPM is drooped way down. Still, he thinks he can save it. But all the king's horses and all of Lycomings as well cannot bring the RRPM back up into the green.

I bring this up because this very situation happened to me back when I was a very young and very dumb helicopter pilot. (No, not last week...I said young!) Luckily for me I was in a one of PHI's finest 206Bs and only pulled to 100%. Also lucky for me was that I was empty. Luckier for me was that I was up at 700' when I began that dumb stunt. But I can tell you, when that ship started backing up and falling through, I was one BUSY sumbeeatch! And there was a moment (or two) when I actually thought we were going in the drink.

I can absolutely sympathize with the R-44 pilot - I've been in his shoes. Thankfully, my feet weren't on his pedals that time.

P.S. I did not intend to comment on his state of arousal, but I can assure you that in my instance all the blood in my body ceased circulating when my heart stopped, leaving not a drop to travel to or engorge any other part.

[Chris Burke]

So could this have been avoided by applying some collective during the flare, to stop any sink and therfore go into an HOGE? or is there a bit more to consider, ie heavy and a downwind flare?

I'm young and still wet behind the ears, but that looked very easy to get into and did happen pretty quickly. I get the feeling he was downwind and a bit heavy and flared, once TL had gone he sank, pulled a load of collective quickly to try to stop the sudden sink, and as previously said over pitched, RRPM decayed and no time to do much else but try and put it down as best he can.

Chris

[Thomas coupling]

In the mil I used to teach bringing the a/c to a faststop with the RCDI not moving from 'level' (I know - you should be looking out!). When the stude was happy that he/she could "feel" that the a/c wasn't sinking at all and got used to the considerable application of collective as the engines compensated for the drag curve, then and only then did I teach them to transfer their references to 100% visual out of the window in future.

We also taught fast approaches to oil rigs for rappelling. This entailed leaving it till late for a fast stop BUT bringing the a/c UP to the platform from slightly below, just as the a/c stopped, to prevent any sink whatsoever.

In the police when flaring quickly to a hover for FLIR activities, always flare UP to the correct level - again to prevent any sink rate developing.

If you are learning on a new type, be sure to quickly assimilate the rate of application of lever that the aircraft drag curve requires whilst bringing the aircraft to a halt. Always remember where the wind is - ALWAYS.:=