If the power required exceeds the power available, RRPM will always decay, this is basic stuff. What also needs to examined is the rate that the power is demanded ie how quickly you pull on the "going up" lever vs where the TRT vector is tilted at the time of collective application.
25-30 deg NU, heavy, hot & humid (we have already heard tail wind component arguements) on termination with rapid collective input (high rate of demand) can/will result in RRPM decay. Combine this with checking level to the HVR attitude prior to dismount/disgorge = bunting and decaying the RRPM even further. If you're generous you would say a
HEAVY Landing will be the result...........
"OR"
Maybe the
TACTICS employed need refining and DECU's would only assist not
FIX the problem.
Max
