‘Bravo73’, the situation with respect to the AW189 performance is far more complex than you or ‘tottigol’ have portrayed.
Leaving aside the ‘clear area’ procedure for a moment and looking at the Category A vertical procedure using ‘ISA’ as a reference point (+15C and 0 PA), it has an RTOM of 8050kg (MCTOM 8300 kg):
- the procedure is to climb vertically to 110’ (TDP};
- following an engine failure at, or before, 110ft it can reject vertically to the helipad;
- following an engine failure at or after TDP, it can perform a Continued Take-off (CTO) clearing the surface by 15ft.
Because these are early days, it does not have a variable TDP but an assumption can be made that, if it can survive a power-unit failure and reject at 110ft, there would be no ‘performance’ barrier to this level being raised. (I have my doubts, however, that there are sufficient visual reference to reject vertically from this height to an elevated helipad, let alone higher).
(In the performance section of the RFM, a similar WAT curve (for vertical reject and fly-away) is provided for all categories – in fact it appears to be a mirror image of the reject curve. This replaces the H-V Diagram, quite legitimately, using the converse of the wording from 29.1517 “if a range of heights exist at any speed, including zero, within which it is not possible to make a safe landing following power unit failure…”)
In the performance section, there are WAT and take-off procedures for Category B: one from a HIGE and a second with a rolling start; there is a ‘Category B take-off distance chart’ that applies equally to both. It is not clear if there is any advantage for one over the other because, for both techniques, the RTOM are identical. The MCTOM of 8300 kg applies for quite a wide operating envelope.
There is presently only one Category A ‘clear area’ procedure – rolling to 25kts (how does the pilot know when that has been achieved unless it is GPS derived and displayed on the PFD?); at 25kts GS the reference Tq (PI target – the Tq to achieve a 2m hover) is pulled and the helicopter is climbed to the TDP of 30ft. it is not intuitively obvious what advantage is gained by using this rolling technique bearing in mind that the mass for this procedure is not much greater than that for the vertical (at ISA, 8300 kg as opposed to 8050 kg).
One disadvantage with this procedure is that it cannot be used in PC2 under circumstances where the surface would permit a safe-forced-landing but not a running take-off or reject.
There is no Category A take-off mass WAT as specified in 29.25(a), 29.67(a)(2) and required by 29.1519 but this is not unusual for European helicopters certificated by EASA (we know not why)! AH do provide this in the performance data for the AH225 but not in the limitations section (the S92 has it in the limitations – i.e. in compliance). This data is required for operations in PC2 in order to determine the second segment climb and therefore the take-off mass.
Comparison with other helicopters is difficult because of the unique way that data has been provided.
I stand to be corrected on any/all of this.
Jim