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Old 28th Dec 2012, 11:03   #141 (permalink)
 
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So according to Flyting from the RFM, and lack of any other meaningful response, we still don't know in what conditions, if any, level flight can be maintained in a 350 with a T/R drive failure. Shame and surprising, given the huge number of hours that must have been flown on 350s worldwide. Maybe the reality is such a failure is virtually unheard of, apart from newfie's impressive experience, which was compounded by engine failure. Any further update on likely cause? Fuel cut off lever position might be interesting - to have such little damage after a T/R drive failure the engine must surely have not been delivering power.
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Old 28th Dec 2012, 12:14   #142 (permalink)
 
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Quote:
Pray tell, how is one supposed to control yaw when selecting fuel off with low forward speed on final approach?
That's the thing, in a power-on t/r failure you can bring the aircraft in (usually on a shallow approach so I do know why Eurocopter ask for a steep approach) and when the aircraft begins to rotate (due to the lack of tail rotor control) you can cut the fuel to counteract the effect of the torque on the airframe. Performed well you can even manage a zero or slow forward speed touchdown (critical in some landing areas).

But to answer you question Anthony, the answer is - that I don't know! Sorry.
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Old 28th Dec 2012, 12:41   #143 (permalink)
 
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Am I wrong to think with a failed Tail Rotor drive shaft.....the tail rotor is not going to be providing any thrust as it is not going to be turning with any rapidity if at all. It might be wind milling a bit...but that isn't going to be of much use I should think.

Thus, my view is one is confronted with the procedure in the RFM that pertains to "Loss of Tail Rotor Drive"....which in most helicopters means an autorotative landing is the preferred technique.

My question still stands....."Can the 350 be flown to a suitable landing site without the Tail Rotor being driven by the MGB?".

Surely there are some 350 pilots out there that can give us the answer or at least quote from the RFM section that discusses that situation.

I cannot believe this is a bit of aeronautical mystery that remains unknown, unexplored, or is taboo to discussion.
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Old 28th Dec 2012, 13:13   #144 (permalink)
 
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Sas,

Loss of t/r drive is a Land as soon as possible event. Not Land Immediately.

From my RFM (although for a B3):
3.3 Tail-rotor failures
3.3.1 Complete loss of tail rotor effectiveness
3.3.1.3 In Cruise flight:
1. Cyclic: Adjust to set IAS to Vy and control yaw
2. Collective: Reduce to avoid side-slip
Land as soon as possible

Approach and landing
On a suitable area for auto-rotative landing:
1. Twist-grip to IDLE detent
2.Carry out an auto-rotative landing as landing procedure.

Vy= 65kts at sea-level

It's been many years since I last flew a BA so I can't remember exactly, but I can't really think the procedure is much different as the main difference between the two is the engine.

Last edited by Nubian; 28th Dec 2012 at 13:21. Reason: adding info
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Old 28th Dec 2012, 13:47   #145 (permalink)
 
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Firstly I am sure you can cruise for as long as you like at the power / collective setting that gives you the least side slip . I am guessing around 60 knots straight and level with low torque .
Secondly I have done simulated failures with what we considered to be neutral pedals ( lifting both feet off doesn't work as the blades naturally throw some pitch on so you have to push some opposite in )
If you do a shallow approach with wind off the R H side you can get right down to 20 kn or less before touch down . You can either grab for throttle ( 6 inch gap from collective ) or you could get the pax to pull it back when you say pull !!! This is all on BA so same for all 350 s except B3 and Mil .
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Old 28th Dec 2012, 14:30   #146 (permalink)
 
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Minimum side slip is for comfort mostly.....and controllability and structural loading as factors....but speed can vary if needed. Most of us are uncomfortable if side slip goes beyond what we normally experience in our day to day operations despite the aircraft being quite safe at large angles of slide slip.
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Old 28th Dec 2012, 15:07   #147 (permalink)
 
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nigelh, this makes sense and is similar to what african eagle wrote - so why is the FM recommending a steep approach and to power off the engine before landing?

Does anyone know the different t/r fail procedure on the B3 and is this due to the FADEC?
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Old 28th Dec 2012, 15:50   #148 (permalink)
 
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Quote:

Can't you guys stopping speculating on the unknown or shall we remove the
first 'p' of PPRuNe?
Not posting often here, but really tired of reading
post from self-called professionals...
Keep the rumour mill turning, but for
god sake stop the speculation going a one way strret when we all know that most
of incident/accident are happening when more than one hole of the swiss cheese
align...

Good day
Kami
You forgot about the "Ru" of PPRuNe.

And Shawn never said that hyd were the cause of this accident, but rather an issue with the 350, especially in cold weather.

It killed a very skilled pilot in Canada in one particular incident that I am aware of.
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Old 28th Dec 2012, 16:17   #149 (permalink)
 
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Quote:
Firstly I am sure you can cruise for as long as you like at the power /
collective setting that gives you the least side slip . I am guessing around 60
knots straight and level with low torque .
Secondly I have done simulated
failures with what we considered to be neutral pedals ( lifting both feet off
doesn't work as the blades naturally throw some pitch on so you have to push
some opposite in )
If you do a shallow approach with wind off the R H side
you can get right down to 20 kn or less before touch down . You can either grab
for throttle ( 6 inch gap from collective ) or you could get the pax to pull it
back when you say pull !!! This is all on BA so same for all 350 s except B3
and Mil .
Loss of drive is not fixed pitch neutral. The fact it is spinning at a high rpm keeps it aerodynamically active. LTE would be a closer approximation.

SAS, I do not have first person experience but have been told that a 350 was relatively flyable w/o t/r drive. As well, a friend of mine had a net take his out and landed in a cut block w/o additional damage.

From a theory perspective, on every sim session I attend, someone asks if continued flight is possible w/o t/r drive and invariably the technician explain that no manufacturer has data on it and they make a series of assumptions to program the model. Not something that can be simulated in a real a/c unless you are willing to put a hand grenade in the tail boom.
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Old 28th Dec 2012, 19:29   #150 (permalink)
 
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Sorry , I don't believe the t/r does continue to spin and create thrust . Also it would actually be quite easy to put a t/r on a rig and blow wind over it etc to prove . Lets just accept you can fly without it !!
I am happy to demonstrate if someone has a 350 they want to risk .... I would want a runway to land on however !!
There are also incidents where people have flown after losing t/r drive .
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Old 28th Dec 2012, 20:18   #151 (permalink)
 
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I should have explained better. I agree, without drive it would be stopped. I was talking about using neutral pitch as a simulation of loss of drive being inaccurate.
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Old 29th Dec 2012, 12:36   #152 (permalink)
 
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I'm fully aware of the gasp reflex that occurs in cold water,
but still surprised that, having cleared the cabin, they were found just 50 ft from the aircraft

Mickjoebill
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Old 29th Dec 2012, 21:40   #153 (permalink)
 
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Without suits and a raft, clearing the cabin merely gave them the choice of dying in open water as opposed to the cabin of the sinking helicopter!
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Old 30th Dec 2012, 02:13   #154 (permalink)
 
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drop the passnegers before ditching?

I once (and never again!) was in the rear seat of a media chopper that crossed a large body of European water, without raft, immersion suits or floats for a 20 min trip in summer.

The pilot discussed the emergency procedure of a controlled ditching where I was to jump out at say 20 feet and he would fly further on and then ditch. A reasonable option given the possibility of becomming tangled in video cables in the cabin. A couple of cameramen have become tangled in cables and kit and unable to make an exit when other occupants survived a ditching.

Maybe we'll never know if this crew didn't exit the cabin until it was inverted deep under water and they were already half drowned. Is the concept of jettisoning a passenger before settling in the water a good idea if there is no raft on board? especially if the cabin has (deriggable) monitors and other contraptions onboard?



Mickjoebill
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Old 30th Dec 2012, 03:07   #155 (permalink)
 
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Makes sense to me.

I seem to remember the controlled ditching brief we used in Hueys was that we'd come to the low hover, let everyone but the captain jump out, who would then move a reasonable distance away, turn the force trim on and try to get it so the aircraft would move away to the left as he jumped out the other way.

Something like that, unless it's brain cells I've killed in the meantime, which is a good possibility.
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Old 30th Dec 2012, 11:23   #156 (permalink)
 
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Grrr gliding distance of land.....

Do we all remember the TV series Magnum?
From island to island with a standard Hughes 500. No floats, vest,etc!
Millions watched this.

There are things one can do and not do....but you should always have a "way out"!
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Old 30th Dec 2012, 12:14   #157 (permalink)
 
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If we have decided the aircraft could have been flown with the Tail Rotor Drive Shaft failed....what else could have put them into the water?
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Old 30th Dec 2012, 12:24   #158 (permalink)
 
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Quote:
island to island with a standard Hughes 500. No floats,
Do you mean this Hughes 500?

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Old 30th Dec 2012, 12:52   #159 (permalink)
 
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Magnums Helicopter

Yes, also.
But notice they never, as far as I could see, worn vest or had a dingy on board.


"Quote"
The show used several different Hughes 500-series choppers for filming (and a 369D early in the first season), each with a slightly different setup and look. The main differences were with regards to the tail and skids - T-tailed (500D), Y-tailed (500C), high skids, short skids, skids with floats, and gray and tan interiors were all used in various configurations. The T-tailed/short skid setup (the 500D) was by far the most commonly seen in the show.
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Old 30th Dec 2012, 13:01   #160 (permalink)
 
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Quote:
If we have decided the aircraft could have been flown with the Tail Rotor Drive Shaft failed....what else could have put them into the water?
Hydraulic systems failure has already been suggested.

There's must be many more possibilities:

*MRGB failure
*Contaminated fuel
*Fuel Control Unit / FADEC

and other components.
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