It had potential disaster written all over it, right from the beginning.

Good points.
Accepted.

He had a wind from the right which helps in a right power pedal aircraft. = stable so far

He planned to yaw left to align with the pontoon putting the wind further round. = reduction in right pedal to yaw left

When he attempted the go around, his yaw pedal position was very far behind where it needed to be and then he got weather-cocked to downwind and panicked. = needed enough right pedal to stop the original yaw and more to compensate for the handful of power pulled.

I don't know what Tq warning indications there are on the 120 but the Gazelle had a red flashing light that then went on steady.

In this respect I agree with Megan than concern about overTqing might have prevented him using full right pedal.

So instead of a mild overTq taking a couple of hours off the transmission - he crashed the aircraft instead!!!!!

I'm not familiar with this aircraft type. I just assumed it would have a digital engine control that wouldn't let you do anything too nasty to the engine and it would restrict power to a limit and then bleed off RRPM if you applied more collective.

No protections, it's got a nice big FLI display (Zero-Ten scale, 10 is T/O power limit, and a red triangle above for the transient limit).

The Tq limit below Vy (65kts) is 103%, but you are able to pull through that up to 110% for a transient of 5 seconds without penalty. A horn comes on after 1.5s in the transient range to let you know you are there, and nothing on the aircraft would stop you from pulling beyond in order to avoid an accident.

The below has relevance:


From the actual ATSB Transport Safety Report. Page 35:

Page 34:

Page 75


And finally Page 77, confirming what crab said:

Stall of vertical stabiliser / tail fin?
 

It is correct that in a CW rotating helicopter, wind from the right 'unloads' the anti-torque device. In other words, the wind pushes in the same direction as the tail rotor thrust vector. Stable so far, OK, but for how long?

When I did my type conversion on one of those French Fenestron-equipped helicopters, I was taught the that there is a specific problem with wind from the right, related to the stalling of the vertical fin:

• A large portion of the anti-torque thrust of a Fenestron comes from the airfoil profile of the vertical stabiliser = at forward speed the tail fin creates lift supporting the Fenestron.
• That tail fin stalls at a given given speed and Angle of Attack, like any other wing.
• While wind from the right initially supports the Fenestron (ie, requiring less right pedal), the same wind from the right increases the AoA of the relative wind. The increased AoA makes the tail fin stall earlier (at higher ground speed).
• The change of right pedal required (from pre-stall pedal position, to the position required post stall) is more dramatic in this scenario, as due to the right wind initially the right pedal required was lower compared to pointing straight into wind.

It was said that many pilots got caught out this way. The convex training put specific emphasis on sensitising new pilots for this specific "gotcha" scenario.

Probably most have seen this paper already, but for the few who may not have it has some relevance: ERF2019-0017.

We operate an EC120 amongst other types. When flying heavy you are in constant fear of an over torque. Takes you back to the robby days, of having to plan out every approach carefully beforehand to ensure you don't bump it over the red line. Everything (wind etc) needs to be stacked in your favour. In my experience it is a huge distraction. The problem is that the engine produces a lot more power than the transmission will handle, so there is always a hesitation to put in a boot load of right pedal as this is the quickest way to an over TQ. I reckon that was at least a consideration by the pilot here, if not a large part of the cause of the accident. This is NOT the case in the other fenestron equipped machine I fly regularly, the EC130 where you can happily use up all the pedal travel without pushing the FLI into the red.

Are we saying the EC-120 is poorly designed?

I personally think the EC-120 is a delightful helicopter.
It does not have a large power margin like an AS350 B2/3 for example, or an easily ignored power limit like an R44 at sea level, for example.
Much like many helicopters (B47/B206/A109A/B222 for examples) it requires some thought, intelligent and appropriate techniques applied, especially when loaded near max gross weight.
I’d rate it’s performance as very similar to a B206III (But it won’t run out of TR authority, and it will record any exceedance’s)

Considering it is a much newer design, and the size of the boot - the performance is disappointing*, and leads to pilot induced problems. But you can’t depart vertically in B222B at max gross weight either, even on a cool night. Well, I can’t.

*Potentially designed this way, to prevent competition with other Airbus products.

Every helicopter with a vertical fin will experience changes in the lift it produces at various speeds and the Fenestron equipped aircraft just have bigger fins than most - as Hot and Hi says, to offload the Fenestron in forward flight.

I think it less likely to have been a factor in this accident since he was already in a low speed situation when the yaw started and the main effect of the vertical fin would have been felt as he yawed to give himself a downwind component - a tendency to weathercock towards complete downwind would have been the result, not a stall.

I think we are all in agreement that another pilot crashed another helicopter that had nothing wrong with it. The next example is just around the corner and will appear here soon enough for sure.

Close to or at MTOW you have to plan your flightpath with most helicopters very carefully.
I recall pleasure flights with the Bell 206 where the ground crew brought the fat father with the fat mother and the fat kids just after refuelling - forcing the doors shut....
When I was young and not bold enough to say - NO
Creeped away in the ground cushion (but that's another thread here on PPRUNE)
Only, that the EC120 is recording over limits - while other conventional helicopters doesn't - shouldn't prevent a pilot to over torque - if it is required to survive.
Its shameful - and shouldn't be done on e regular basis - but better than crashing ...
If the other helicopters could tell, how often they have been mistreated - you would have to listen to long stories...