Helicopter down outside Leicester City Football Club

[Capt Pirate]

I knew Eric of old and as soon as I heard about this crash I knew it was mechanical not Pilot error. He was a sound steady Pilot. RIP.

[ApolloHeli]

One area that puzzles me is there is no analysis of the different outcome in survivabilty if the landing gear had been down at impact...
They do, Page 126 from the report (my bold for emphasis):
Impact assessment
The helicopter manufacturer carried out an assessment of the deceleration loads experienced during the impact sequence using recorded and calculated data provided by the AAIB. The assessment considered the loads on the helicopter’s structure in the region of the fuel tanks and rear row of passenger seats. It also considered the possible differences had the helicopter’s landing gear been extended.

The assessment identified that with the landing gear extended, there was no significant decrease in the forces transmitted through the helicopter’s structure. The manufacturer stated that this was because the calculated rate of deceleration and the forces involved exceeded the landing gear’s ability to react, deform and dissipate the impact energy.

And to address this:
Maybe I misunderstood the report but I believed the TR Pitch went to FULL POWER. Which leaves no chance of a recovery as we saw in this event. No just loss of control . The worst scenario imaginable. Its odd that all other manufacturers fit a safety mechanism, or inherent blade aerodynamics, that would "center" the servo to a reasonable, hopefully survivable pitch setting. I also understand this latent failure event exists in 109/139/169 and 189. Are there any Leonardo techs on here that could confirm this.
The report states (page 27) that the forces experienced by the tail rotor control bearing in the axial direction (pitch changing direction) are all stabilising (centrifugal and aerodynamic loads seek 0 pitch, and the elastomeric loads seek 0 deformation on the elastomeric bearing). However, the hydraulic force on the tail rotor control rod was still present to overcome these forces and the tail rotor pitch continued beyond full 'non power pedal' deflection as the tail rotor control stops were no longer interacting with the tail rotor pitch control rod. Page 160 of the report (my bold for emphasis):
The actuator lever mechanism is designed to act as mechanical feedback for the hydraulic actuator, closing off hydraulic pressure once the movement of the control shaft matches the pilot’s pedal input. As the lever was now completely disconnected from the control shaft, the shaft continued to move under hydraulic pressure without restriction.

[Wide Mouth Frog]

This is an extraordinary failure by the certification authorities and the manufacturer. Attached is a paper from the CAA from 2003 where precisely this gap in certification requirements in was identified, and a rulemaking task initiated in what was JAR at the time. Clearly nothing came of that, or if it did, it was lost (again !) in the transition to EASA. Then it seems that Leonardo's own design department 'forgot' its own experience on the AW139 where it installed the mitigation of the LH thread nut.

But there is an operational issue that seems to have been overlooked, and that is that the helicopter was 75ft (I think) above its planned TDP and commencing a turn before Vmini or Vy. Every pilot who flies a CatA departure profile knows without being told that having everything hanging out at the top of the backup is a very vulnerable position to be in, and is therefore in a hurry to get through that and away to the safety of forward flight. I guess we'll never know what happened here, but I would have been interested to see if the helicopter had been regularly operated this way.

Finally its pure speculation, but the fact that VSKP had the worst degradation of its duplex bearing for the fewest hours of any machines in the fleet might not be unconnected with the nature of this stadium operation with its long drawn out backup at high power.

[Variable Load]

The H175 doesn't have any information regarding what a crew can expect if there is a loss of TR control. There is no drill, and there is no simulation. Yet there is a single cable run, and a clearly identifiable hydraulic failure sequence that will both lead to no TR control should things go wrong. As Wide Mouth Frog indicates, is there a gaping "critical single point failure mode" not covered in CS-29 regulation?

[Wide Mouth Frog]

Come on you TREs and you FO(T)Is out there. What do you think ? Nobody is risking anything, the CAA already laid it out in lavender in 2003. How happy are you that these wide gaps exist in certification of new helicopters, grandfathered designs in older helicopters, and training ? And how happy are you that the regulatory bodies and apparently at least two manufacturers (Airbus and Leonardo) have utterly let down the pilot community ?