Fenestrons are great but pilots have to understand that they behave slightly differently from a conventional tail rotor.

Some of the anti-torque thrust comes from what has been described as 'lip-lift' where the flow around the duct adds to what is being produced by the fenestron itself - a bit like a coanda effect.

When you get a situation where something affects that flow and disrupts the 'lip-lift', the demand for power pedal is suddenly increased to compensate and, if you are not on top of your game (or ahead of the aircraft) you can end up with a left yaw you weren't expecting.

There is still more than enough TR authority but it requires you to use a bit more pedal - this can sometimes be masked by the TR linear actuator if you have SAS or AP in yaw.

This is where the myth of Fenestron Stall was born - and subsequently disproved by Aerospatiale TPs. It hasn't stalled and you don't have a TR malfunction, you just need to apply more right pedal - perhaps all the way to the stop!

This isn't usually a problem but at high power, many pilots are reluctant to use that extra pedal due to the marked Tq spikes (also typical of fenestron equipped aircraft) experienced if you are less than gentle with the yaw input.

You can see this effect when you accelerate sideways (or hover crosswind with the wind from the right) - eventually you get to a point where the airflow through the fenestron needs to reverse as you apply lots of left pedal - there is a marked yaw disturbance but you still have full control and as you pass through this, normal feel is resumed. The same happens as you slow down again and that is where the Tq spike can occur, as you push right pedal to re-establish 'normal' flow again.

Airbus put out a safety notice a while back emphasising that the thrust from the fenestron vs pedal position wasn't as linear as from a conventional TR but slightly S shaped - for the reasons mentioned above.

If the pilot in this case, in gusty winds and manoeuvring to land, experienced what he thought was a TR problem, it might go some way to explaining the result.

BTW - a gully is defined as a 'water-worn channel' so it will have been created by water and may periodically contain water - how is that different to a wash:)

Crab,

Your posit is possibly biased with Gaz experience which is only natural.

The fenestron on a 130 is near enough identical to that on the 135 albeit a mirror image wrt to direction of rotation.

The MGW of the 135 internal is about 450kg greater.

When was the last time you heard of issues on a 135 fenestron wrt to controllability?

I'm calling -

http://i0.kym-cdn.com/photos/images/...57/323/c3b.png

RVDT - based on 341 AND 365, both of which exhibit exactly the handling qualities I detail.

Did you not see the Airbus SN then?

Edited to add it was Eurocopter Service Letter - 1673-67-04 so its a bit older than I had thought.

LMGTFY - http://airbushelicoptersinc.com/imag...elicopters.pdf see particularly para 3

Another of the British tourists involved in the crash has died, after 10 days in hospital. RIP.

From the Beeb

Guys, just my 2 cents--I have flown this route hundreds of times for that company in the EC130
There is no issue with t/r authority in any conditions in the 130, you must mash the pedals harder than other boosted types but you can do most anything in any wind conditions.

The weather in the canyon can be very extreme IE: micro bursts, severe up and down drafts, T storms, turbulence etc..

The quartermaster site is a few hundred feet above the river and the pilots are usually very confident of the direction of wind based on a sock above the shade structure for Papillon and other landing traffic etc..

To be all out of sorts on short final to the LZ leads me to think its pilot error or some strange mechanical issue we dont know about yet...!!!

The NTSB gives no clues as to what happened

The pilot will be the only one who can shed light on what happen...!!

In my experience Papillon had excellent MX excellent TRNG during my time..

Only time will tell....

As I pointed out, there is no problem with TR authority - it is just the response in some wind conditions that can catch people out.

At High AUM and high power (ie full of pax and in the latter stages of an approach in gusty wind conditions) some pilots might be more reluctant to 'mash' the pedals than others.

It may not be a factor in this sad accident but we will have to wait for the full NTSB report to find out.

A fifth British tourist involved in the crash has now died, after losing her husband four days ago.

BBC article

And no mention of the background of this investment in safety. I bet somebody wishes they had done that a bit earlier.

Hot and Hi,

I’m sure you are right, but they HAVE made what is no doubt a very expensive decision. They could have just ignored the problem.

Kudos to Papillon.

We had a discussion a year or so ago about the absence of crash worthy fuel cells on many helicopters.

If you climb into one without such a safety improvement....who is to blame?


Might you become an accident statistic tomorrow....and if you do...whose fault is it you went out in a blaze of glory?

Didn't Ford have to recall 1.1 million F150 pick ups 7 or 8 years ago because the fuel tanks were faulty and kept bursting into flames?

Manufacturers will produce what they think they can get away with.

Not to mention the arguably worse Ford Pinto debacle of the 70s, from which they apparently didn't learn a thing...

the recent lawsuit for one paramedic that was awarded 100 million, and the undisclosed award to the second paramedic for their injuries suffered in their crash and fire that killed the pilot, is a huge motivator to do something about the problem. With two survivors remaining and similar lawsuits likely on the horizon, you can bet the bank accounts of airbus and papillon are going to get appreciably smaller again.

Hindsight, I'm personally glad they are taking the steps to modify their aircraft, but who else is? I hope many more follow suit. It really is costly for this kit, but again, look at the lawsuit cost, is it worth the risk? to some yes, to others no. Its tragic that it took another accident to get to this point though.
will the marketing brochures for the tour operators start listing the fuel tank status in an effort to gain passenger loads over the competitor?? Will customers start asking about the fuel tanks, shoulder harness', helmets and flame retardant clothing for their flights, or will they still be clueless and naive about the serious nature if something goes for a ****. Most believe they are paying for their safety up front and nobody is putting them at risk right???

I was perplexed the day after this accident though, with the smoke hardly cleared, I was seeing facebook posts from Maverick, claiming awards for their maintenance staff and the best maintenance in the industry. You tell me that wasn't ill timed and a low blow, when they should have been supporting their competitors under the tragic circumstances. It shows it's all about money and nothing else. Im actually surprised that Maverick didn't do an ad, with their maintenance staff sitting around a roaring campfire showing off their framed certificates of excellence.

I believe I've heard a saying attributed to the Japanese but applicable worldwide:
"Business is War"

BTW- I'm not endorsing that attitude, just mentioning that it's not unusual nor necessarily unethical, it's just how we are...

Greyhorizon .... you’re not seriously suggesting pax should dress up in flame retardant gear and wear helmets for a joy ride are you ??!!
On that basis they may as well all pack up shop ..!!

i'm not suggesting it, but the lawyers might. the FAA might. The customers if they woke up might demand it. why would they simply stop at fuel tanks? I'm not sure the fuel tanks remove the risk of fire 100%, and I'm sure you will agree.

Flame Retardant clothing for tourist/corporate/air taxi flights might be a bit of a stretch....crash resistant fuel tanks is not.:ugh: