During the time that the EASA working group were considering solutions, AW applied for, and were granted, an EASA Equivalent Safety Finding (ESF) on the requirement to provide an H-V Diagram; this finding was not in compliance with the ‘rules’ - as shown in the post above (the AW 189 is certificated as a ‘Large Rotorcraft Category A and B’). The proposed ESF was commented to that effect but, in EASA’s response, a lack of knowledge/understanding of both the certification and operational requirements was shown.
Jim
EASA AW189 certification team has proved great competence and vision on this subject, unfortunately the H-V NPA working group has missed it completely.
The ELOS was only addressed to the different way of presenting the H-V envelope information and NOT whether to provide it or not provided it, in fact all H-V information is included in the AW189 RFM.
I want to clear some concepts that EASA Cert team has made very clear and agreed with AW proposal.
The H-V limitations applies to takeoff and landing profiles and HOGE conditions for Cat B certification and only for takeoff and landings profiles for Cat A.
Being (by rule) the H-V envelope/limitation only applicable to the type of surface where it has been demonstrated (that in all RFM is hard/runway type surface) this limitation can only be considered applicable to the published takeoff and landing procedures that are the only conditions where the H-V has been demonstrated.
Based on this it was considered compliant, considering the applicable CS29 rules, that H-V limitation was demonstrated.
AW has considered that the inclusion of the actual traditional H-V chart that was fully demonstrated as per the required rules, was of low operational values. AW proposed instead to provide what AW considered a much more valuable information that can be faced in real operations where "usually" very rarely a Cat B takeoff/landing profile takes place over a runway and all HOGE operations almost never occur over it. It was then considered to introduce in the performance section a fully comprehensive set of charts that provide Safe Vertical Rejects and Fly-Away performance WAT charts with an actual height loss data including wind/speed contribution. We wanted to tell the pilot what he can do to save the helicopter and not what he cannot do without telling what is a safe escape.
This was also corroborated by the fact that the traditional H-V information is only limited to one type of surface and therefore not applicable to any other operational surface.
For Cat A procedures, the WAT charts included in the limitations section have been demonstrated to be cleared of any H-V limitation.
I want to reiterate my thanks again the EASA Cert team for their collaboration in achieving a step forward towards a new vision in providing a better and more operational oriented RFM for these class of helicopters.
One more consideration: there are no H-V envelopes for helideck sites, it is impossible to comply with these rules for these surfaces, therefore there are no possible infringements of the H-V limitation. Even a takeoff profile that complies with the published H-V limitation, if carried out from an helideck, can be fatal.
The only safe way to operate from helidecks is to apply procedures with zero exposures, i.e. PC1.