With regards the warning for ROTOR RPM, the report says
"The next recorded warning was rotor rpm signifying an Nr of less than 97%".
Yes, the visual warning was recorded, but without an FDR, how it is not known that all of the 4 ROTOR RPM warnings related to low Nr. It doesn't stipulate exactly.
I think it does if you read the rest of the paragraph, the same paragraph that says there were three Low Nr Warnings ... not your four;
"
The next recorded warning was rotor rpm signifying an Nr of less than 97%. This warning cleared, returned, cleared again and then returned and remained active. The subsequent bat disch warning indicated that the battery was providing electrical power. The final warning was related to the autopilot."
"That was why I was highlighting the similarities between the high Nr gong at 106% and the BAT DISCH gong. Without a timescale for these warnings, they could have all merged into one. That is what I meant by the sound of the gong from the Battery may have affected other audio warnings.
If you look at Table 3, 'Warning Unit - warnings recorded in the NVM' on page 33, the time line clearly shows that the battery discharge gong didn't go off until after the third Low Nr Warning illuminated and remained on.
My point about Nr control; is that when you are trained and tested in the real aircraft, you aim to keep 100-103% Nr, to prevent damage to the head/MGB. This gets ingrained, so that when you have something for real, you don't automatically let the Nr rise, because pilots rarely/ever train full done autos in the real thing in a MET helicopter.
We train to settle the auto with the Nr between 97 and 106, ie the region outside of which you get an Nr warning. However please feel free to look up the power off Nr limitations
This has been proven is some military helicopter accidents where the pilot only flew to the practice single engine Tq figures, as opposed to the real limits (pull the lever up to your armpit) because that's what they always did in training.
Can we have some references please to these military double engine failures resulting in an autorotative landing please, or is that an opinion?
(Lever up to the armpit would surely only apply at the 'cushion on' stage at the end. We cant have the General spilling his G&T now, can we!
But overall, despite all the bells and whistles sounding, and looking at the table 3 on page 33 of the report, there were a few audio warnings, any pilot under a high workload with no spare capacity gets tunnel vision. That was my point about a person's hearing being the first thing to go. (Gongs vs Low tone vs gearbox noises vs cockpit noise).
Referring to Table 3;
Eight Audio Warnings were acknowledged, two of which were after both engines had stopped, so they must have been heard and acknowledged during this high workload, no engine, auto scenario at 100 kts, 1000'. The only audio warnings not acknowledged were the last three in direct succession; Low Nr, Batt Disch & AP ATrim ... right at the very ,very end.
You say nothing can be proven in a case like this, but at least have the respect for everyone involved to look at the facts as presented to you.