Taiwan Coast Guard Dauphin Crash

[skadi]

A Dauphin of Taiwan CG crashed today while winching engineers on board a stranded vessel. One fatality, pilot seriously injured and in critical condition...

1 dead, 1 critically injured in helicopter crash in northern Taiwan | Society | FOCUS TAIWAN - CNA ENGLISH NEWS (http://focustaiwan.tw/news/asoc/201603110016.aspx)

skadi

[SilsoeSid]

RiP
:(

ETzJUk2wnf0#t=28

[Hughes500]

my heart goes out to everyone on board

[Cybernethic]

It seems that there are two fatalities and three persons injured... Unfortunately!

[Vertical Freedom]

Rest in Peace

[lowfat]

truly awful... RIP

[Hedski]

Cause looks pretty clear. Poor guys couldn't do much to save it from a hover.

[chopjock]

It appears to have been hovering tail into wind?

[Hedski]

In that case could fenestron stall be an issue?

[SilsoeSid]

Blimin' tv editing.

:O

[chopjock]

Sid,
That's not the one that crashed.You are looking at the rescue helicopter that was rescuing the Dauphin. Look at this...

http://www.thevideostreams.com/news/loss-of-tail-rotor/

As you can see, it was hovering with a tail wind...

[SilsoeSid]

Yep, just noticed that we are seeing two different snippets of video in one there.

A still pic doesn't give the full story, we can see a bit more of what was going on just before, in this one;

40 secs in;


zB8E0SBsHkw

[9Aplus]

:( RIP

True, first frame is Sea-Hawk in hover...

[alouette]

But the accident aircraft is a Dauphine...? Not the first one involved in an accident in Taiwan...

[Geoffersincornwall]

Fenestron stall does not exist - they tell us - but there is an interesting Aerospatiale Service Letter that explains a particular issue if you are operating a 365 with winds from the starboard quarter (4 'o'clock) as this can induce LTE. The advice if this occurs during take off is to apply full right yaw pedal, reduce collective and land immediately. The letter goes on to say that trying to solve the LTE problem by taking to the skies has never worked.

I'm not saying that this is the cause for we don't have any facts upon which to make a judgement but we do have the video and this suggests a possible LTE situation.

I found this SL after an incident in Cameroon back in 2000 and it was one that had been around for quite a while. Old it may be but relevant it remains.

G.

[[email protected]]

Fenestron stall or LTE would not keep the aircraft spinning like that - as soon as the relative wind changed, the rotation would stop, or at least slow down - ask any Gazelle pilot who has experienced the aircraft swapping ends in the hover over Belfast.

That was a TR drive failure.

[Geoffersincornwall]

CRAB

Maybe a 365 is different, certainly the Service Letter implied that the situation was divergent.

You fly a 365 now so ask the maintenance organisation to look it up for you. My guess is that was issued in the early '90s.

G.

[soggyboxers]

Geoffers,

You're quite correct, it is indeed a divergent condition, with increasing acceleration to the left. Updated versions of the ASL are published on the Helicopter Safety website:

Eurocopter Service Letter 1673-67-04 (http://www.helicoptersafety.org/pdfs/1673-67-04en.pdf)

[Geoffersincornwall]

Thanks Bob, looks like he came in downwind - classic!

G

[SilsoeSid]

Would he have had someone already lowered or lowering on the cable before being 'on station'?

[BOBAKAT]

As Gazelle Pilot , i can say if you lose the control of the tail due to the tail wind, you keep it again after 180° turn, when the nose go to the wind...that's all , no spining ! I experiment that some times

[Max Power 3503e]

That was a TR drive failure.

Loss of T/R thrust for some reason...

[mickjoebill]

A person was being winched at time of the spin. During the spin and descent the person was winched up into the doorway. Not sure if it was a victim or crew member.

Would a pilot have a different response in the first few seconds had their not been a person on the line?

Mickjoebill

[[email protected]]

The service letter amplifies what is already known about Fenestron stall - you need to apply maximum right pedal immediately - it also says it occurs in light winds.

That Taiwanese 365 had a major loss of TR thrust, not LTE or Fenestron Stall - it kept spinning, which doesn't happen with FS - as bobakat says.

As an ex- Gazelle pilot/instructor and a current 365 one, I can say that there is at least as twice as much TR authority in a 365 as there was in the Gazelle and a 40kt cross and downwind limit.

In a strong downwind condition - >20kts - the large tail fin does make directional control a little more twitchy but any tendency to weathercock will be negated as the aircraft comes back round into wind.

Would a pilot have a different response in the first few seconds had their not been a person on the line? almost certainly - he did a great job getting the person on the wire safe - just unfortunate to crash afterwards.

[Geoffersincornwall]

CRAB

I would still put my money on LTE :-)

Big difference between your N3 and it's predecessors if it was an 'N' with little metal blades then it would be way different

G.

[SilsoeSid]

All we see in the vid is the ac moving slowly from right to left of shot, with someone on the wire.

Now then, obviously its only going to be an opinion, but were they;

a. Approaching the pup with the person being lowered down.
b. Flying away from the pup with the person being winched up.
c. Trying to maintain a downwind hover but allowing the ac to stray.
d. Slowly approaching downwind, lowering the person and about to turn left for an into wind recovery.

… just before the rotations began?


Seems strange in such a strong wind to operate downwind and with the amount of other aircraft around, there must have been a pattern in operation around the ship.

[SilsoeSid]

.. he did a great job getting the person on the wire safe, ..

Not convinced about that :eek:

Looking closer at around the 17 second point;


http://i52.photobucket.com/albums/g11/silsoesid/1_zps21auds3x.png

zoomed in;

http://i52.photobucket.com/albums/g11/silsoesid/2_zpsnfuhzqxw.png

[[email protected]]

CRAB

I would still put my money on LTE :-)

Big difference between your N3 and it's predecessors if it was an 'N' with little metal blades then it would be way different
Still don't think so - anyone from Taiwan know which model of 365 it was?

Sid - I didn't check to see if the person on the winch did make it back to the cabin - maybe it wasn't so. However, in the circumstances who can blame anyone?

[OvertHawk]

Crab... I'm pretty sure they are N2s.

It certainly looked as if they were doing their best to get their winchman safely back to the aircraft. He was clearly being winched in as the event unfolded.

Tragic regardless of the cause. :(

OH

[Geoffersincornwall]

CRAB - extract from the SL

In the various cases which resulted in the loss of yaw axis control, the action applied to the RH yaw pedal was not enough (amplitude/duration) to stop rotation as quickly as the Pilot wished.
As the aircraft continues its rotation, the Pilot generally suspects a (total or partial) tail rotor failure and decides either to climb to gain speed or to get closer to the ground.
In the first case, increasing the collective pitch results in increasing the main rotor torque and consequently further speeds up leftward rotation. This results in the loss of aircraft control.

Yes, they are N2's. The N3 has a different (upgraded?) fenestron with asymmetric blades but can't confirm any performance increase over the N2.

[soggyboxers]

Geoffers,

The N3s were indeed fitted with an asymmetric fenestron although some of the earlier models were initially fitted with the same one as the N2. It made a noticeable difference in performance as well as being quieter. I seem to remember that the N3s NHV got originally had the N2 fenestron. A number of N2s were retrospectively fitted with the asymmetric fenestron. If you remember the ex-Maersk N2s Schreiner got and which I gave you your differences course on, they were later fitted with the upgraded fenestron before being moved from Nigeria to Sudan. The big performance difference in the N3s however, came from the engine upgrade. It did give us a lot of starting problems in Cameroun so we always carried a portable GPU and had little battery powered fans and additional ventilation in the baggage compartment when we shut down on the pipeline.

With the wind from the wrong direction incipient LTE could be a problem with any of the 365 models.

[Um... lifting...]

Well, I've watched the video, and I'm not entirely sure what caused this, because I don't know the windspeed, the magnitude of the pedal input, the density altitude, the mass of the aircraft, the pilot's degree of caution in causing an overtorque. You know... the et ceteras. Perhaps someone looking at an image of a helicopter the size of a flying termite can draw more information from this clip than me, or perhaps they have greater skill.

But then again, my experience in Dauphins is limited to a mere 4000 hours in the 366G1, 365N, N1, N2, & N3.

[[email protected]]

CRAB - extract from the SL

In the various cases which resulted in the loss of yaw axis control, the action applied to the RH yaw pedal was not enough (amplitude/duration) to stop rotation as quickly as the Pilot wished.
As the aircraft continues its rotation, the Pilot generally suspects a (total or partial) tail rotor failure and decides either to climb to gain speed or to get closer to the ground.
In the first case, increasing the collective pitch results in increasing the main rotor torque and consequently further speeds up leftward rotation. This results in the loss of aircraft control. Geoffers - remember it talks about light wind conditions only, because in any stronger wind the directional stability will stop the spin or slow it enough to regain control - it won't keep spinning like the one in the video.

Have any of the long-time 365 pilots here ever experienced fenestron stall/LTE that spun you round and round like that?

[Geoffersincornwall]

CRAB - consider that the fact that the aircraft in question was moving downwind at the time and losing translational effect therefore pulling more collective to maintain height.

I don't think EC would have issued an SL like this if they did not have good reason. I suspect there are a whole bunch of 'incidents' that we are unaware of. If they say don't try and fly away with this issue going on then they must have lost few to that problem.

If not LTE then what would the failure mode be? Is there a history of drive shaft failures?

Anyway, sad day for the Taiwanese CG. If there are lessons to be learned then I hope they will share them.

G.

[SilsoeSid]

The downed helicopter was returning after ferrying EPA technicians to the ship when it was reportedly hit by a high wave and spiraled into the sea.
http://www.taipeitimes.com/News/front/archives/2016/03/12/2003641375

[[email protected]]

Geoffers - I think the SL is a bit of an a*se-covering exercise as it highlights that correct pilot action (ie full right pedal) will stop the spin. This was ably demonstrated by a French TP to put to bed the myth of Fenestron stall on the Gazelle - he established a 120 deg/sec rate of yaw and stopped it dead with full right pedal (and a little bit of an overtorque, but that is better than crashing).

Note the SL refers to ALL TRs, not just the Fenestron and simply shows the thrust response from pedal position is essentially linear with a conventional TR but more S - shaped with a Fenestron.

The SL primarily concerns itself with occurences in the low hover where incorrect pilot action could easily result in trying to land with a high rate of rotation - not usually a good outcome from that - the Taiwanese 365 was in a high hover so LTE/FS is very unlikely to be the problem since it would be easy to flyaway from it.

However - Sid's link (which I can't get to) might be a possible answer - a big slug of seawater through the fenstron could easily trash the TR driveshaft due to the sudden drag.

[Geoffersincornwall]

Concur with your analysis although I have my doubts that lessons learned on the Gazelle can be applied to the N2. The blades on the later models were notoriously fragile so a slug of seawater could well have set the whole thing off.

There but for grace of god etc etc.

G.

[cpt]

Hi Geoffers,

Yes there have been at least an history of a drive shaft failure on a 365N.

A close friend of mine experienced a failure of the output flector (# Thomas Coupling ) at the main gear box output level. The design is the same on the N3.

It happened on a rig take-off .... first heavy vibrations with a loud banging jerking noise, than the armed floats deployed uncommanded (due to combined vibrations and the shocks of the ofset turning shaft still attached to the flector banging against the "mechanical Floor" that triggered the floats relay located just above on the "mechanical floor" )

The pilot, on the very early stage of the take-off managed to turn back to the deck, where he slammed the helicopter down as the flector completely broke.

It is interresting to note that the inflated forward floats almost completely impaired his downward vision to aim at the center of this small helideck.

I can add, that after many thousands hours(#8000) on different versions of 365 and also Gazelle flying not only offshore but also aerial work (long line,sling, movie shooting, picture taking, survey, military etc....) I've never experienced, nor never heard one of my colleagues talk of a so called tail rotor stall or fully developed LTE on these types.
Could it be pure luck after all ?

[Greeny9]

Cpt,
I would imagine the floats inflated due to the vibration in the Immersion probe (shorting it out) manifested by the airframe vibration rather than the flector banging against the 'mechanical floor' triggering the relay.

The older Immersion probes were known at times to be the reason for setting off the floats uncommanded due to either sand build up or even water shorting in flight (rain) as well as internal vibration within the probe.

[SilsoeSid]

Link is still good.

Taipei Times (http://www.taipeitimes.com/News/front/archives/2016/03/12/2003641375)

Perhaps the ship was acting as a 'breakwater' and the wave came off the far side.
Anyway, plenty of ship movement going on; maybe the 90 degree difference of ship heading during the operation could be a factor?!

http://i4.mirror.co.uk/incoming/article7538853.ece/ALTERNATES/s615b/PAY-Taiwan-helicopter-rescue.jpg

http://img1.cna.com.tw/Eng/WebEngPhotos//CEP/20160311/201603110016t0001.jpg

[cpt]

Hello Greeny,

No, on the 365N I was refering to in my post, immersion probes were not installed... and it didn't ditch anyway.

As with this poor Taipei 365, I can't tell as we don't know yet what caused this crash. But the rotation rate looks pretty much what we experience in the sim when we simulate a tail rotor shaft failure on hover.

[Greeny9]

Cpt,
Ok, understood but my point about the floats firing off (if you have an immersion probe) is it could be initiated in flight without submersion.

[cpt]

G'd evening Greeny

Understood too (I'd read your post a little too fast) but the interesting point here, is about uncommanded floats inflation in case of accidental short circuited immertion probe ... BTW, do you know if the so called "AFDS" system is modern enough for not being afected by this fault? (that's the one we have installed on our 76s)

[Greeny9]

Not familiar with S76

[John R81]

Once the rotation starts, the continued acceleration of rate as the tail comes back towards the air flow seems to me to make TR shaft failure much more likely than LTE. I have not flown this model, but a 120 will "swap ends" like others say of the Gazelle, and once weather-cocked it all slows and gets considerably less exciting. In this vid, the excitement level just kept going up and up.

[squib66]

Once the rotation starts, the continued acceleration of rate as the tail comes back towards the air flow seems to me to make TR shaft failure much more likely than LTE.

It turns out it was neither:

Tail Rotor Pitch Control Loss During Hoisting (http://aerossurance.com/helicopters/trpc-loss-hoisting-as365/)

[tartare]

So if I read that right - the poor soul on the end of the hoist was flung uno into the main rotor by centrifugal force?
Jesus - that's awful...

[squib66]

So if I read that right - the poor soul on the end of the hoist was flung uno into the main rotor by centrifugal force?
Jesus - that's awful...

Yes, that does seem to be the case. If they has successfully cut the cable it probably would still have been a fatal fall.

[Aser]

The ASC note that due to the expense, simulators were not being routinely used by NASC crew.
===>
The copilot also heard the pilot saying, “What is happening to the aircraft?”
The accident was going to happen anyway BUT maybe someone would be alive today...
:ugh:

[squib66]

Would sim practice of recovery from a TRCF in a relatively low hover have made a big effect on the survival probability, especially if the winch op was not involved?

[Aser]

We will never know, it was too expensive to even try...
***facepalm***

[S76Heavy]

I seriously doubt you can replicate the exact behaviour of a fenestron failure in a sim. It will simply not rotate in the same manner. Perhaps it will teach the correct response. perhaps it will teach a wrong response that will work in the sim but not on the aircraft (very much like offshore landings).

[squib66]

I seriously doubt you can replicate the exact behaviour of a fenestron failure in a sim. It will simply not rotate in the same manner. Perhaps it will teach the correct response. perhaps it will teach a wrong response that will work in the sim but not on the aircraft (very much like offshore landings).

That was what I was thinking. I do agree that generally not doing sim raining because it costs money is an indefensible position.

[212man]

I would have thought a fenestron failure at low speed is relatively simple to simulate, as the aerodynamic modeling is less complex than forward flight. It's simple physics. The Helisim EC155 always seem to behave in the manner I'd expect, and the stuck TR controls certainly replicated real world training with jammed pedals. One session will always stick in my mind, where the crew were given a TR drive failure in the cruise st 2,000 ft. They decided to do a handling check (on an aircraft that was basically still straight and level). Eventually they washed off the airspeed and the 'thing let go'. Unfortunately, we never reached any 'crash' parameters to 'red screen' and freeze. Conversely, I couldn't reach the stop button as I was hanging on to the grab handle. My colleague had been thrown on the floor from his jump seat and was covered in books and papers. It took a while before we hit the ground. Seemed pretty realistic to me!

[SimFlightTest]

Simulating tail rotor failures (as well as fenestron failures) have far fewer unknowns in the low speed regime compared to the cruise environment. In general, such failures are relatively straight forward to have the simulator produce an "acceptable" response... acceptable being defined as a response predicted by a physics-based simulation that also satisfies the expectations of pilots.


That being said, the behavior will undoubtedly not be validate against actual aircraft behavior, so there will always be room for uncertainty.

[Flying Bull]

I would have thought a fenestron failure at low speed is relatively simple to simulate, as the aerodynamic modeling is less complex than forward flight. It's simple physics. The Helisim EC155 always seem to behave in the manner I'd expect, and the stuck TR controls certainly replicated real world training with jammed pedals. One session will always stick in my mind, where the crew were given a TR drive failure in the cruise st 2,000 ft. They decided to do a handling check (on an aircraft that was basically still straight and level). Eventually they washed off the airspeed and the 'thing let go'. Unfortunately, we never reached any 'crash' parameters to 'red screen' and freeze. Conversely, I couldn't reach the stop button as I was hanging on to the grab handle. My colleague had been thrown on the floor from his jump seat and was covered in books and papers. It took a while before we hit the ground. Seemed pretty realistic to me!

SIM-Time might help to condition a pilot to react in the right manner instead of asking "what t.. f... is the helicopter doing...."
I found it really impressing, how violent the the movement was even at a fenestron-failure at hover in ground effect.
Not slamming the collective down and bouncing all over the runway would lead to violent movements as noted above with loose parts flying through the SIM and a crash screen....
Wether the height would have been sufficiant for a complete recovery? I doubt it but may be a more controlled crash would have been possible with a slighty higher chance of survival.

[[email protected]]

Guess what? - It spins out of control and in a moderately high hover with a man on the wire, someone is going to get badly hurt, there is no good outcome because a crash is inevitable.

[megan]

not doing sim raining because it costs money is an indefensible positionMoney was the reason our big oil employer gave for only allowing captains to attend every three years, and copilots not at all, since it involved a trip half way round the world. Their aviation adviser said he saw no value in sim training, yet he attended yearly, but the word "safety" had been mentioned, so the company relented to the above extent. That was twelve years ago I admit though, hope things have changed.

[Flying Bull]

Guess what? - It spins out of control and in a moderately high hover with a man on the wire, someone is going to get badly hurt, there is no good outcome because a crash is inevitable.

You're right, a crash is inevitable.
And the outcome is most likely with badly hurt and even dead crew.
The difference could be in the numbers and the severity of injuries, when the pilot has experienced an failure in the SIM, reacted right in slamming the Collective down while pushing the nose down and into the turn to gain speed which would stabilise a helicopter with a big fin like the Dauphin. It would be nose down - flare- crash, cause the altitude might not be sufficiant for an fly away - but chances of survival would be greater than spinning all the way into the sea.

If a company is thinking, SIM Training is expensive- they should look into the bill of a crash.... 🙁

[[email protected]]

You need at least 40 kts on something like a Dauphin for the fin to be effective and by the time you have slammed the collective down and pushed the nose forward, you are already in the water from the height they were at.

Been through these scenarios in the Sea King sim many times and even from 1000' when you know it is coming you are very lucky to survive.

[Flying Bull]

You need at least 40 kts on something like a Dauphin for the fin to be effective and by the time you have slammed the collective down and pushed the nose forward, you are already in the water from the height they were at.

Been through these scenarios in the Sea King sim many times and even from 1000' when you know it is coming you are very lucky to survive.

You're right, that you need about 40 Knots for the fin to work.
But with the collective down, the turn rate wouldn't increase further at a high rate and you're in a "controlled" way down, having a slight chance with a flare at the bottom, or arresting the sinkrate with increasing turnrate close to the water, having a less violent crash.
Guessing from the containers on board of the ship, 150 to 200 feet isn't really much height to play with - but still worth a try.
In you don't react fast enough centrifugal forces won't let you do anything
On a typeratingcourse, with just full pedal pushed, I had the opportunity, to see, what effect the right and fast reaction can have against a slow reaction.
Did that from 500 feet with fly away, still having plenty of height left - but you're right, I knew what was coming.
Having a confidental video from a fellow pilot, who needed a total of 500 feet for the recovery to straight and level - pedal still pushed - but going through the video, less than 200 feet were needed to stop the turn and there would have been a chance for a more controlled crash.
SeaKing - or other conventional tail rotors- probably no chance at all from that heights...

[Aesir]

Report

Tail Rotor Pitch Control Loss During Hoisting - Aerossurance (http://aerossurance.com/helicopters/trpc-loss-hoisting-as365/)

[[email protected]]

Interesting that the operator thought the simulator training was too expensive so didn't do it.

Standard simulator exercises are TR malfunctions as we all know.

The pilot is reported by the co-pilot to say 'What is happening to the aircraft' as it begins to yaw rapidly - perhaps someone with recent sim training would have reacted much quicker.

Sadly he paid the ultimate price - RIP.