JimL
Trying to leave the personal comments out of it, I still feel that you are not addressing the very point that you mentioned - risk ALARP.
By fixating on engine failures as the only source of hazard, I maintain that there is a danger that you replace one extremely remote hazard with others that, whilst also remote, are possibly less remote than the engine failure during the critical few seconds.
Without a balanced assement of all the risks, I don't see how you can claim that PC2e leads to overall risk ALARP. I agree that such an assessment is not particularly easy to quantify, but to omit it is to be blinkered.
Regarding the point about "the continuation in operation of existing underpowered models" and the nil wind thread, I think you are confusing AEO performance with OEI performance. The former is typically limited by transmission or rotor head and not by engine power. The latter is related to installed engine power.
Therefore there can be no guarantee that operation to PC2E will in any way help the AEO case of some of the newer underpowered aircraft such as the 155 - not too bad OEI due to its engines' 30 sec rating, but pretty poor AEO. Operating PC2e from a high deck would still allow high takeoff mass so not addressing the AEO performance issue.
Modern aircraft with marginal AEO performance can be more dangerous than their predecessors due to FADEC AEO power limiting. In an older aircraft one can in extremis normally pull to max contingency power on both engines. No doubt damaging the transmission but maybe not actually crashing.
Modern aircraft typically limit AEO power to the certified transmission limits, so you won't overstress the MGB but unfortunately you might crash as a result. Even those that have FADEC blowaway are little better because whilst the older aircraft can give max power on both engines whilst the rrpm is still normal, those with FADEC blowaway only give max power once the rrpm has become very low. Since thrust is a function of rrpm and torque, an overpitching crash is more likely in the new types, eg following an unexpected event such as weather or structure-induced downdraft.
So I am all for increasing AEO performance since this has potential benefit on every takeoff and landing, except the 1 in 10^9 when the engine fails during the few seconds of exposure. But its not related to OEI power nor to PC2e.
(sorry for thread drift on to AEO power, but you started it!)
HC
Last edited by HeliComparator; 18th Feb 2010 at 20:27.