R22 down near Ely, Cambs: Jan 2012

[RJC]

From a 'tweet' from Cambs Police, this article is up from the Cambridge Evening News...

Cambridge News | Latest News Headlines From Cambridge City & Cambridgeshire | National News By Cambridge News | Emergency services rush to 'fatal' helicopter crash (http://www.cambridge-news.co.uk/Home/Emergency-services-rush-to-helicopter-crash-06012012.htm)

Emergency services rush to 'fatal' helicopter crash

Helicopter crash at Witchford
Emergency services were today called to a helicopter crash. It is thought there has been one fatality in the crash. The fire service said they had been called to Lancaster Way in Witchford. A single, light helicopter crashed at the former airfield. Two crews from Ely are there and a rescue vehicle from Cambridge is on its way.

They were called at 11.33am to reports of an accident close to a business park. A police spokeswoman said:

"Police and emergency services are currently at the scene of a helicopter crash in Witchford near Ely. The force control room was called by a member of the public at just before 11.30am today (January 6). They reported seeing a helicopter go down in a field behind Lancaster Way Business Park. At least one person is known to have been in the aircraft, however, I have no details of injuries at this time. "A corden has been set up around the crash site but no roads have been closed."

A Marshall Airport spokesman said the aircraft did not fly from the Cambridge area. He said it was thought to have been flying from Manston Airport in Kent to Fenland Airfield near Spalding. The helicopter was, he added, said to be a Robinson R22 two seater.

Clare Blair, of Evergreens, Chesterton, said her daughter's partner Pat Masterson had been walking his dog on the airfield when the helicopter crashed.

Mr Masterson and Mrs Blair's daughter Alexandra run the vilage stores in Stretham. She said: "Pat had been walking the dog on the airfield and the helicopter crashed right in front of them."
Mrs Blair said Mr Masterson had called the emergency services from a nearby house and had tried to get the pilot out of the helicopter.

If accurate, sad news indeed...

[helihub]

http://www.cambridge-news.co.uk/imagelibrary/Client%20Images/Client00004/00207000/00207705.jpg

http://www.peterboroughtoday.co.uk/webimage/1.3397398.1325869945!image/3843259725.jpg_gen/derivatives/landscape_595/3843259725.jpg

[Bravo73]

RIP :(

BBC News - Man dies as helicopter crashes in Cambridgeshire (http://www.bbc.co.uk/news/uk-england-cambridgeshire-16445371)

[wallism]

Very sad indeed, and it's gorgeous flying weather here today for the first time this year.

[Lewycasino]

Photograph of Aircraft G-CHZN (http://www.caa.co.uk/applicationmodules/ginfo/ginfo_photo.aspx?regmark=G-CHZN&imgname=G-CHZN001&imgtype=jpg)

[captain_flynn]

Sad news indeed :( RIP.

[chopper2004]

RIP poor guy. Do tend to drive past that area quite frequently albeit at weekends however not today.

Haven't check TAFs today but wondering what conditions like however down in Cambridge to the naked eye generally was blue sky sunny morning onwards to afternoon.

Condolences to family and friends.

[g-mady]

sad indeed

Looks like quite an impact...

MADY

[toptobottom]

What a dreadful start to the year... :sad:

Doesn't look as though there was much forward speed on impact.

[Avitor]

Eye witness said it appeared to break in two and drop. His words, not mine.

[toptobottom]

I wonder if that's the same witness who said it was black?

Re. '...the 'break in two...', the fuselage looks largely intact but I can't see the MR blades?

[JP27]

doesn't look like there is any info on identity of the pilot yet, as the official reports say this will come only at least tomorrow

[cyclic35]

My sincere condolences to family and colleagues.

A dreadful start to 2012. R.I.P.

[topendtorque]

Very sad alright a god awful heavy impact and one in which a more than normal curiosity is raised,
to wit;


Richard Dunk, from the Stockshop warehouse at Lancaster Way Business Park, said he was having lunch with a colleague when they "heard a bit of a bang".
"I turned around and saw the helicopter coming down with a lot of smoke coming out of the back."


I wonder if a radar trace is available to help with investigations?


The helicopter pilot had been talking as a matter of routine to our air traffic control as it passed Cambridge Airport."

[P6 Driver]

As always, a large pinch of salt is required until official reports are available - BBC Ceefax is currently quoting an "eye witness" as saying it was a black helicopter he saw crash!

A bad start to the year.

[FLY 7]

Many helicopters, even white ones, appear 'black', when in flight at a reasonable distance, especially if the prominent light is behind it.

[FSXPilot]

Thanks for saving me the bother of pointing this out. Just because the observer saw it as a black helicopter does not negate the rest of what they saw.

[P6 Driver]

That's exactly why details should be taken with a pinch of salt until the official report is out...
:ugh:

[blakmax]

In this case, it may be appropriate to wait for the official report, but I am very familiar with one crash where the report was forwarded to the authorities in a small Pacific nation over two years ago, and it has not been released yet. The frustration is that the report addresses an (at least superficially) similar crash. (Loud bang, parts seen to depart the aircraft, fire, blade located away from crash site.)

The significance is that the report advanced a novel explanation for why the blade failed and caused the crash, and IMHO it should be available for the investigators for this case, even if only to discount that cause for this event.

Regards

Blakmax

[talkpedlar]

IMHO I believe most Ppruners viewing this thread (well those with Robbo experience/knowledge) will already have a pretty clear idea of what happened here... and I doubt that the AAIB will need assistance from afar to determine the cause. Another tragic loss nevertheless... RIP buddy

[helops]

...what do you mean? Must-bumping???

[Andy Mayes]

The identity of the pilot has been made known via other channels so I expect the press will pick it up tomorrow (Monday).

RIP my friend, you were one of the real good guys. See you again.

[[email protected]]

Helops - can't see where talkpedlar mentions 'mast-bumping' (maybe he removed it) but it is a condition that can occur in a teetering head helicopter when less than normal G is experienced.

A 'pushover' type manoeuvre, where the cyclic is moved quickly forward, can reduce the G to a point where the main rotor stops influencing the attitude of the fuselage and abnormal angles between the MR and the rotor mast can occur. In relatively benign situations this causes 'mast-bumping' but in extreme cases the MR can impact the tail boom with disastrous results.

Not saying that is what happened in this case but it is a well-documented factor in some Robbie accidents.

[hillberg]

Can't see the main gear box or mast-Poor guy never knew what happened,RIP

[topendtorque]

IMHO I believe most Ppruners viewing this thread (well those with Robbo experience/knowledge) will already have a pretty clear idea of what happened here


No this one doesn't have a clue as yet, if the witness correctly reported smoke, then it may be hot oil smoke from one of two sources, that is why i am intrigued. I see what looks like part of a blade left side of pic.

Does the AAIB publish interim reports within a specified timeframe?

[talkpedlar]

I haven't deleted or changed anything.. or mentioned mast-bumping....

Don't expect anything from the AAIB for 9-15 months but, although I carefully avoided speculation earlier, my own view..based on the reported "bang" and clear evidence of high vertical-speed impact, is that this may well be yet another mast-bumping tragedy... Please don't flame me... I was well versed in R22 operations and accident investigation. Again, RIP ol buddy. TP

[Aucky]

talkpedlar - based on the reported "bang"

Not hoping to speculate on this accident, but a general question - why would mast bumping lead to a loud "bang"? the tail looks intact (no obvious strike), if the mast had sheared would that itself be audible from the ground? or is it that without the weight of the helicopter keeping the mast vertical the remaining output from the MR gearbox would start to flail around ripping itself to bits, which in turn would surely dismount the gearbox, and drivetrain etc... just wondering from your history of accident investigation.

Cheers

[AmyJLowe]

This was my Dad's first helicopter that he bought just after he passed his test :/ such a shame :( had my first flight in Zulu-November :(
When he had it, there were no technical problems and he'd had it serviced too.
RIP to the pilot, may he find peace.

[stringfellow]

well im about to start the robbie safety course in california in a few hours and day one is all about crash reviews. il have a natter to them about this one. can someone please tell me what their suspicion is on this one rather than dilly dallying around. they may be totally wrong and thats why we have the aaib at hand but the im sure there are loads of people that will benefit from a stimulated debate.

another sad day for flying. rip.

[helimutt]

G-CHZN
This was my Dad's first helicopter that he bought just after he passed his test :/ such a shame had my first flight in Zulu-November
When he had it, there were no technical problems and he'd had it serviced too.
RIP to the pilot, may he find peace.


I'd be worried if he hadn't had it been serviced! :ooh:

[61 Lafite]

My condolences to the pilot.

I went to the safety course last year - good luck and it's well worth it.

*If* the investigation rules out mechanical failure or maintenance issues, and *if* it is true that the mast and blades ended up separated from the main wreckage, then mast bumping would appear to leave a tell-tale set of marks on the bump stops and the rotor mast breaks in a relatively identifiable place. The rotor mast and blades would usually fall a distance from the fuselage. I used to check my 22/44 for marks on the bump stops before each flight, I think a lot of people do, it's not something one wants to see.

Carb icing (or any other loss of engine performance) leading to rrpm loss, followed by failure to successfully enter autorotation and catastrophic rotor stall often chops the tail in a relatively identifiable point (I think it's the third sheet back from the tail rotor, plus the blades would cone up, but from recall of accident reports, I don't remember seeing reports where this caused the entire set of both blades to separate - Richard Mornington Sandford would probably be the UK expert on this stuff, and what the indicators are which they use to determine cause.

The reports often seem open-ended, because a precise understanding of the start of the sequence of events simply cannot be established. And without investigative expertise and access to far more information than we have, only the experts will figure it out.

It is a source of unease to me that most Robinson pilots have the low-g mast bumping issue rammed into us repeatedly, but it still appears to happen (whether in this incident or not) more than I'd like to see. I find it hard to believe that all the incidents where it happens can be attributed to poor pilot skills, but clearly events still play out in a way whereby reasonable pilots still end up in a fatality.

This may only ever be cleared up when very lightweight and inexpensive data recorders become available for these small rotorcraft,

Lafite.

[toptobottom]

The problem with mast bumping is that once in a low G situation and if the aircraft rolls to the right, the instinct for a low time PPL is to apply left cyclic to correct the roll, instead of first re-loading the disc. I have seen reports where the top of the mast has sheared off due excessive bumping, meaning the rotor head, complete with the MR blades, separates itself from the aircraft. If the 'breaking in two' witness statement is accurate (and if the fuselage is as complete as it would seem to be in the photo), then one could be excused for thinking that was the likely cause.

However, the witnesses also said they saw "a lot of smoke coming out of the back". Even an unreliable witness would struggle to imagine such obvious evidence, so catastrophic engine failure and subsequent failure to do an auto might be more likely. Whatever, I'm sure the reason will be obvious to the AAIB by now.

[moonburn]

Amen to that Andy, One of the best in every sense of the word and a real gentleman and total professional. A very sad week for the training world and so many friends. Let's hope we find out the reasons quickly. MB

[hillberg]

Watching From the start of Robinsons manufacture to now. The loss of the Hub & Blades from the R-22 during the mast bumps & blade delams, make for some nasty crashes recovered,The Main gear box has allways remained with the wrecked airframe this is the first from the pix taken where the mast & cowl is not shown,(Is it on the far side of view?) The tail is still attached so no normal blade strike, Fractured mast? Strange ,RIP.

[powerlimited]

It goes without saying a very sad accident.

Whilst it would appear the identity of the pilot has been kept out of the press, do we know their experience/qualifications?

Regards
Pwrltd

[Andy Mayes]

Whilst it would appear the identity of the pilot has been kept out of the press, do we know their experience/qualifications?

GA instructor/examiner on fixed wing and commercial flying on the EMB 110, FI examiner/instructor. He has also recently been flying a BE20 but I'm not sure if this was as Captain or FO.

Several thousand of hours on all manner of fixed wing.

PPL(H) which he completed a few weeks before Christmas.

[stringfellow]

great discussion some informative stuff even if we may all be proved wrong?? my question is, speculating it is mast bumping, how on earth could a standard cross country flight from a to b result in it?? i mean if he was doing low g manoevers over ridge lines i could understand. but on a cross country?? maybe as a fixie he nosed over hard to avoid something?? but boy it would have to be a hard dive??

[herman the crab]

RIP to a fellow aviator - very close to a CFI(H)'s home that I know well - fortunately (selfishly) not him.

stringfellow - shame I am headed back to the UK tomorrow or could have had a beer and gone flying locally! Enjoy the course - who is taking it?

Andy Mayes - I;m guessing you put fixed wing in bold for a reason (Robinson safety notices)?

HTC

[stringfellow]

now then crab a beer and a fly out would have been great, what a shame. tim tucker is running it he of the old 2.4 second throttle roll off with no collective response... must have very big balls, and/or small brain!!!!! seems a great course mind.

and as we summise a fellow aviator who had the curiosity to venture into the mysterious world of rotating parts is no longer with us. such a shame.

[herman the crab]

Yeah it would - the flying first of course and mine's a rum :) Not sure how long you are in town for but if you can find someone local to take you flying go for it - totally different to flying in the UK. The low level LAX shoreline transition/downtown at night/etc. PM me if you want a recommendation for a school that can arrange it - no connection other than an acquaintance owns it and I have flown their ships a few times.

Tim is a great instructor/examiner - he did my private and commercial checkrides. His tales are worth a book on their own. The first time I did the safety course he taught it and it was by far the best of those I've done. Have you noticed how many of the accidents (shown on the course) are in the UK...

Make the most of the chance to push the R22/44 to the absolute limits with the Robinson pilots - you won't get the chance (and probably wouldn't want to risk it) anywhere else.

HTC

How are the donuts/cakes/pastries? :)

[toptobottom]

How are the donuts/cakes/pastries?
Haven't you guys got email? Getting back to the thread...

Although extreme mast bumping might explain the MR separating from the aircraft (indeed, if this happened - it's almost impossible to tell from that one grainy photo), it doesn't explain the 'lots of smoke'. Given the topology and weather, I'd be very surprised if mast bumping had anything to do with it.

[herman the crab]

RIP to a fellow aviator - my first comment. I don't know him but for the grace of god (or whoever) it could be me...

So sorry for a little thread drifting - albeit related to R22 safety. A change from the speculation based on news reports and untrained witnesses maybe?

Yes I have email and I am sure stingfellow does too - however without connecting through the thread it is unlikely we would find out each others.

He is doing and I have done the course that may save our lives flying the Robinson machines - mutual ground between pilots - the same mutual thing that may one day kill us too. I am sorry a comment about that course offends you so much. Maybe discussing the fatal accidents shown, poor training, training accidents would be more appropriate?

I rarely fly the Robinson these days but learnt on them and personally think the subsided course is well worth the money and if it brings pilots closer together to discuss avoidable accidents then it has to be good.

HTC

[topendtorque]

i should have asked before how old was the machine and was it still matched up on components?

re this;
See SN-29. "Airplane Pilots High Risk When Flying Helicopters"


I don't think that was needed,
The gentleman had been check and training on banderante I believe, a definite plus for instilling in his mind a process to think through all considerations for emergencies - always. He has also just had the exposure of new training, not as if he had been sitting around for years and decided to go for a fly. It would be a very strange instructor that didn't show him the pitfalls of high time F/W vs low time R/W.

cheers tet

[bladeslapper]

tet
G-CHZN was a 1988 a/c originally reg as G-GHZM. I purchased the a/c in early 1999 immediately after a 1st Robinson overhaul and re-registered it as G-CHZN. PDG (Wolverhampton) carried out a second overhaul for me in 2007 after which I sold it.

For me it is a sad end to the a/c which was the basis of my flying and my thoughts go out to the pilot's family as for all of us there is an element lurking in the corner of our minds that says ' there but for the grace of god .....'

[[email protected]]

Stringfellow - he wouldn't be the first FW pilot to react incorrectly to an engine malfunction in a helicopter - the old adage of 'when under pressure you revert to what you were first taught' may be applicable here. FW pilots when faced with an engine fail in the cruise will inevitably push forward to retain speed rather than flare. If you combine this with an adrenaline fuelled lowering of the lever because you know the rotor inertia is poor, you can quickly generate a low G environment which we know is a bad thing for Robbies.

Just supposition of course.

[rotorspeed]

More supposition - pushing cyclic forward abruptly to avoid a bird strike?

[Thomas coupling]

IF it was MB:
FW jocks wouldn't do anything at all if a donk stopped in their multi engined a/c, the autopilot would trim and slow automatically:).
He might have reacted this way and just did nothing.
In a helo (single and twin), instinctively a rotary pilot would lower the lever to contain Nr (we would all agree on that little baby!) and in so doing, the a/c would pitch down automatically due to the impingeing air from below on the stabilisers. Most helo pilots end up having to contain the amount of nose down that occurs for this very reason.
So, mast bumping/tail cone contact could easily occur during this nose down episode and/or by overcorrecting the pitch down by too much aft cyclic.
He may have reacted this way.

In a Robbie - an uninitiated FW pilot would have his work cut out.

[topendtorque]

FW pilots when faced with an engine fail in the cruise will inevitably push forward to retain speed rather than flare.


I have bugger all in F/W, only singles and less than 3K. Their cruise speed is usually a fair bit more than best range glide speed. What I was taught was to pull up for more height if possible. I discarded that later and simply adopted a technique off bleeding off airspeed until the best range speed appeared and trimmed it at that attitude. I figured much less energy waste, whether I was turning to a spot or not. Don't forget this gentleman was a F/W instructor.

Re the bird evasion that is possible I suppose, but i personally think it very unlikely that he would have suffered a serious mast bump by simply pushing forward on the cyclic even with down collective.
Don't forget serious mast bumps are often coupled to blades going way out of whack and severing the tail boom and or the cabin, which did not happen.

The smoke was not a fuel fire or it would have been burning on the ground.

Oil could have been ingested from a ruptured xmon through the cooling fan and blown over the exhaust, mucho smoke! Or spilt on the exhaust from an engine rupture. Or it could come from the belts. These new belts don't seem to smoke before failure, they just break as far as I know.
The old belts will smoke but not for long before failure, say a few seconds, i think it unlikely to be seen from the ground, just a hunch.

I can't presume he didn't lower the lever after a simple belt or engine failure because the aricraft is inverted. In a rotor blade stall they nearly always land right way up with the blades acting a bit like a wind vane after they bend.

Also quite often before they bend properly they will strike the boom or the cabin.

I guess if the blades were the old variety and a few hundred hours old it is reason enough to suspect a delam causing a blade breakage, which fits nicely with a bang when it breaks and bits seen falling elsewhere, but once again why the smoke. Maybe that could have ruptured the xmon?

The blade delams on the R22 that I know about haven't failed because of it and make a very loud swishing noise which is absolutely unmistakeable, no comment about that either.

But then again I could be way out of whack with all of this.
I would dearly like to see a photograph from the other side.

[cyclic35]

"he of the old 2.4 second throttle roll off with no collective response... "
Was there any cyclic flare to encourage RRPM during the initiation of the simulated engine failure, in the absence of lowering the collective?

[stringfellow]

i dont know but i will ask the question for you!! i suspect not, it was at 100kts so i guess the deceleration of the ac would have helped a bit. im told the 2.4 sec was electronically measured,,, testing is testing but it sounds a needless risk to me.

[cyclic35]

OK Stringfellow.

I will PM because I feel my comments are off-topic, especially in the very sad circumstances that generated this thread.

I wish to apologise to members for my lack of sensitivity.

[jellycopter]

TC

You've brought the pedant out in me.

You wrote 'the a/c would pitch down automatically due to the impingeing air from below on the stabilisers. Most helo pilots end up having to contain the amount of nose down that occurs for this very reason.'

The nose down pitch of a helicopter in cruise flight as a secondary effect of lowering the collective (or the nose up pitch from raising the lever) is due to 'V squared' effects of advancing v retreating blade and subsequent phase lag acting 90 degrees later. It's got nothing to do with the upwash/downwash on the horizontal stab - have you seen the size of the R22 stab? This can be seen in flight as the pitch up/down is instantaneous, long before any RoD flow has had chance to develop.

Back to the topic..........

JJ

[[email protected]]

Jellycopter, you beat me to it - it's just flapback/flap forward. I'll nip upstairs to the Sim and give him a clip round the ear!!:)

[jellycopter]

Crab

Yes, I've got my pedantic hat on today. Get TC to give you a clip round the ear whilst your at it!;)

We normally consider Flapback (forward) to be a result of changing airspeed.

Pitch up / down in the cruise, as a secondary effect of collective, is a result of V squared and does not require a change in airspeed. With collective input, the pitch (CL) on advancing and retreating blade is changed by the same amount but the V Squared is hugely different resulting in significantly different amount of lift change on advancing and retreating sides of the disc. This causes the blades to flap and the effect is felt 'approx' 90 degrees later, hence the pitch up/down of the aircraft.

Similar to flapback, but not quite the same.

JJ

[stringfellow]

cyclic thanks for the message but if anyone else is interested i asked chief pilot tim tucker about the 2.4 sec lag. it was a test flight at vne plus 10% when he closed throttle. he did not flare the ac to maintain rpm but he held attitude with gentle aft cyclic, and coupled with the deceleration from vne plus 10% would clearly have helped.

and back on topic today in the auto rotation section he mentioned what happens if you jam in left pedal by mistake at entry. now i may miss some bits or get it wrong, im only a fresh faced newbie, but as left goes in ac rolls left out of trim. relative airflow (plus stalling blades too??) creates a right rolling movement that inverts the aircraft.. and this poor chap in ely landed upside down it appears???

[cyclic35]

back on topic today in the auto rotation section he mentioned what happens if you jam in left pedal by mistake at entry. now i may miss some bits or get it wrong, im only a fresh faced newbie, but as left goes in ac rolls left out of trim. relative airflow (plus stalling blades too??) creates a right rolling movement that inverts the aircraft.. and this poor chap in ely landed upside down it appears??? PM to Stringfellow very rewarding. "Fresh Faced Newbie also" and would like to contribute this link. Please click link and scroll down to the relevant information.
NEGATIVE G AND MAST BUMPING | Becker Helicopters (http://www.myaviationschool.com/aviation-articles/becker-helicopters/negative-g-and-mast-bumping.html)
Stay safe out there.

[topendtorque]

Stringfellow,
It is a possibility and the two that I know of were violent rolls right over. Each time there was an instructor on board who was able to power up and land. I just missed seeing one such event by about ten seconds. I don't know what their recovery technique was and I feel that the one I saw had forgotten by the time he landed, for which I don't blame him at all.

In that case the engine oil blew out all over the place and was all over the tail boom when it landed.

Certainly one must keep an open mind. As a previous F/W instructor he would have known that he had to act in some way and had he not been taught the procedure of entering auto from a sudden engine failure then he could react incorrectly as others have.
His flight training Records might be a good place to start.

Of course there is other stuff to promote the theory. No fire on impact, which if there was any large quantity of fuel on board with that sort of impact is very likely to burn, meaning he may have experienced fuel starvation for a variety of reasons to stop his engine.

The smoke can be explained by oil being blown out of the engine only if it was running.
Perhaps if they were the new type of belts and they broke it “might?” be heard from the ground.
Had the belts broken suddenly and being inexperienced in R/W he may have been confused by the noise of the engine over revving but delivering no power, and to recover from an inverted position without power and the RRPM decaying badly might well be difficult, I don’t think anyone would know.

I think it easy to believe that a roll inverted with no power applied immediately would show as a blade strike on the aircraft somewhere, unless he then did suffer a severe mast bump which allowed the head and blades to fall seperately.

A sad conundrum for sure
tet

[AnFI]

absolute/relative minefield - ( also relevant to pressures - 500hPa is not negative pressure - just LOW pressure - )

... between 0g and 1g is LOW g

... at 0.9g it is not so low that you'd bother calling it LOW

... less that 0g (eg -0.5g) is NEGATIVE g (and LOW g)

[[email protected]]

Jellycopter - pedantically, flapback is considered under the umbrella of flapping to equality (like inflow roll) and in this case the effect of raising the lever creates an inequality of lift across the disc because of the difference in V squared such that the disc flaps back - exactly the same result as when increasing speed - hence my use of the term. Just because CFS doesn't call it flapback doesn't mean it isn't - they probably would if it was in AP3456. ETPS deals with both in the same paragraphs in their notes. Don't forget, some of us were teaching this stuff before you completed your pilots course;)

ISTR that the correct term for this is something like 'pitch instability due to collective application'.

[Thomas coupling]

JJ: sadly you are quite right. [I salute you!].
In mitigation I was trying to steer clear of the AP series of explanations so as to keep the conversation 'light', now you have sent most spectators off to sleep. Secondly, I was actually thinking 'gazelle theory' when I was writing it, where airflow on the underside of the 'stab' does have quite a noticeable effect all be it secondary.. Thirdly, it all seems so long ago...............
Crab: you fell for that old chestnut re: Flapback...tut, tut.:D

[stringfellow]

Thanks for a really informative reply topendtorque, the notion of fuel starvation to me seems quite eye opening, and looking at the accident site no fire seems intriguing.

[muffin]

if you jam in left pedal by mistake at entry..... but as left goes in ac rolls left out of trim. relative airflow (plus stalling blades too??) creates a right rolling movement that inverts the aircraft.

This statement AIUI from Tim Tucker caught my attention. I have done about 500 hours in R22s in the last 12 years and have also attended Tim Tucker's safety course, but I have never heard this one before. Would any of the experts here like to comment, and also offer a suitable recovery strategy?

[puntosaurus]

I've had a student do the wrong pedal on me on entry to auto in a 22, and it was extremely unnerving. Horn sounded and RPM dropped like a stone but I don't remember any roll. Recovery action (which came embarassingly late) was to stick the proper pedal in.

As part of the FI course you're taught to guard the stick and brace the pedal to protect against wrong inputs, but I guess after a few years I'd gotten a bit casual about it. If I remember there's a safety notice about it too.

However I have seen the EC120 demonstrate the opposite roll in response to pedal input under autorotation so it is possible.

[austeriser]

Steady on everybody. As far as I know I was the only pilot (FW) to witness this accident. Most of the stuff you have seen in the press is highly inaccurate but I will not make any comment until after the inquest. AAIB and the Police are still taking statements. Traumatic incident for everybody and our thoughts are very much with the family.

[Bondu121]

Well said Austeriser

:D:D:D

[[email protected]]

Muffin - generally in a helicopter, the secondary effect of yaw is roll in the same direction so in the example quoted it seems nigh on impossible to make it roll right when you have put in a bootfull of left pedal.

If you failed to lower the lever following an engine failure then any rotor stall would tend to start on the retreating side where the AoA is highest - that would give a pitch nose-up and roll left (on a counter clockwise rotor) so combining the 2 errors would seem to make it impossible to roll right.

The 'ususal' way of getting inverted in an R22 is during the low G pushover type manoeuvres, detailed in previous posts, where the only thing producing thrust that can affect the fuselage is the TR which then yaws the fuselage left followed by a roll (secondary effect) in the same direction.

[feathering tickles]

Crab,

My understanding of your post (0850) is that you're saying that an R22 will roll LEFT in low-g conditions, is that correct?

[topendtorque]

now i may miss some bits or get it wrong, im only a fresh faced newbie, but as left goes in ac rolls left out of trim. relative airflow (plus stalling blades too??) creates a right rolling movement that inverts the aircraft


I agree, maybe you might have missed something. The first part is right, err when he says "rolls left", but the second conflicting phrase, "creates a right rolling movement" might have meant to have been "creates a 'right-royal' rolling moment" which is to say, a helluva rolling movement. That's what I would think is a good way to describe it, when speaking to an Englishman perhaps. Or you got your directions mixed?

As far as recovery I would take a punt that the one I nearly saw kept rolling, pulling at least a bit of pitch and he had the power back on, but how much of an interruption was caused to power it as it went through upside down I don't know.
I saw it when he was still in a steep diving turn to the right, going at a fair clip heading 180 degrees from his original entry. So i "think' he initiated aft cyclic as he was rolling to the 270 degree mark. He continued the turn rolling left out of it and slowing, straight onto the pad. Then the instructor departed at VNE for the rest room.


As part of the FI course you're taught to guard the stick and brace the pedal

Which stick? The up and down one I hope you are referring to, not the which way one. What they do with cyclic won't hurt unless you're in a rigid head machine I guess, but by gees I was nearly caught out once many moons ago with an incorrect pull on the ol' heave-ho by one bloke. Now my hand stays just above it and they won't get past it I can assure you. After the incident referred to above, now I won't let the right pedal get back at all, they can try to push the left one all they like.

I agree austeriser, and we should keep the mood light and abstract, only pertaing to raised technical matters. I do hope every one is bearing up OK.

all the best tet

[[email protected]]

Feathering tickles - it would depend on how low the G was and exactly what the pilot was doing with the cyclic but yes it would roll left, unless the TR was much higher than the fuselage ie a lot of nose down - then it would have a moment arm about the fuselage to possibly create a right roll as well as the left yaw.

[feathering tickles]

Thanks Crab, nicely disambiguatified (sic).

[stringfellow]

Many thanks for the replies im sure many have enjoyed reading them. Bear in mind i was only refering to what i heard about the wrong pedal input on entry to an auto, and i may have either misunderstood, or misheard it. But, im sure i heard right, and to add clarity to the debate the conversation involved the left pedal input rapidly decaying rpm to stall point that i think only crab alluded to... i thought that stalling blades stalled and coned evenly, unlike say a retreating blade stall that stall on the retreating side only.

Il get my coat now.

[longbox]

The pilot has been named today and our thoughts should be with his family
Tragic news RIP

[Andy Mayes]

Even though I knew who it was a few hours after it had happened, seeing my ex-instructor, colleague and friends' name in print in such circumstances is just horrid.

I've been in aviation for 15 years and known a few people who have died in accidents which are all very sad but this one has really got to me.

Thought's go to his wife and 2 young girls.

RIP Bob.

[topendtorque]

stringfellow

and to add clarity to the debate the conversation involved the left pedal input rapidly decaying rpm to stall point that i think only crab alluded to...

Yes he did, but in your inexperienced state you should be careful in interpreting. The retreating blade may well stall as it is rolling quickly and thus confronting an increasing A/A- but I suggest not because only of the higher power required by the left pedal input dragging the RRPM down with the engine power curtailed after a period of time, say a second or so while everyone sits fat dumb and happy and waits for it to happen- and then, and then wait for it, here we go - yup, the aircraft rolls toward the stalled section of the disc. ho hum.

That is a nonsense. as had the RRPM gone so low for that to happen there would have been no hope of recovery whilst the RPM decayed further as it was rolling inverted.

What has happened according to two first person accounts each of whom suffered very little RPM decay as they are here to tell the tale, was the full left pedal set up a rolling moment, exacerbated violently and immediately by the fact that the advancing blade is now suddenly exposed to a change in direction of the relative airflow such that it is blown upwards as a rolling moment to join the previous T/R rolling moment to force the violent roll that is referred to. As an analogy I would liken it to a sheet of loose iron in a very gusty wind, when all of a sudden the edge of it is lifted a little to expose the underside to the gust and whoosh the iron flips udside down quicker-n-the-eye-can-see. Comprez?

To say that a recovery would be had by simply changing pedals is a nonsense, obviously that aircraft was already in a different configuration before the left pedal input. In the above two scenarios the left pedal was instantaneous and of full deflection, before the collective was put down.


i thought that stalling blades stalled and coned evenly, unlike say a retreating blade stall that stall on the retreating side only.

yessir tha's right.

feathering tickles
WRT to crab's explanation of low G pushover rolling moments, I am sure he won't mind if I refer you to Robinson SN11, where it discusses a "powerful right rolling moment on the fueslage". You can look it up on the Robinson web site.
tet

[wallism]

Don't mistake Stringfellow's humility for inexperience. Anyway I'm amazed that we now have four pages without a single fact. Great result.

[toptobottom]

we now have four pages without a single fact

On the contrary, and despite being a rumour network, there are many facts from which many on here can learn.

Rumour: a story or statement in general circulation without confirmation or certainty as to facts.

[[email protected]]

Just to clarify:

The R22 rolls right in a pushover (low G manoeuvre) because of the tail rotor thrust.

My mention of left roll was purely to highlight what happens if you stick a bootfull of left yaw in, either in normal flight or following an engine failure.

The AoA distribution on a rotor in forward flight means that the highest AoA is always on the retreating side - therefore if the blades are allowed to slow down, the stall will still occur here first because of the high AoA due to the lowest V squared on that side - blades will only cone up and stall together in a zero airspeed configuration (still wind hover).