The Robinson R44 pilot’s operating handbook low rotor RPM recovery procedure did not include reference to the minimum power airspeed for the helicopter as a consideration, which may assist a pilot to recover from a low rotor RPM condition. [Safety Issue]
Robinson Helicopter Company have conducted two internal reviews of the safety issue and have concluded that safety action to address this safety issue is not necessary. Therefore, the ATSB have elected to close the safety issue as not addressed.
The ATSB recommends that the Robinson Helicopter Company reviews the R44 pilot's operating handbook low rotor RPM recovery procedure for consideration to include a reference to the minimum power airspeed (Vy) for pilot awareness.
We have reviewed the R44 Pilot’s Operating Handbook low rotor RPM recovery procedure to consider including a reference to the minimum power airspeed. The procedure given in the POH for responding to low RPM is “lower collective, roll throttle on and, in forward flight, apply aft cyclic.” These three actions should be performed immediately and simultaneously. Applying aft cyclic in forward flight has a significant effect on helping to restore RPM, regardless of airspeed. Following the RPM recovery, the pilot may then choose to accelerate or decelerate to Vy if he has a need to climb in a power-limited situation. We consider RPM recovery and adjusting airspeed for best climb performance as separate events. We do not believe that a reference to Vy in the RPM recovery procedure would assist a pilot to recover from low rotor RPM.
Thank you for your consideration and the ATSB acknowledge the response provided below. However, before a decision is made about the recommendation the ATSB would like RHC to consider the scenario where a pilot is making a pinnacle approach or confined area approach at low airspeed and high density altitude, as these situations may result in a low rpm warning close to obstacles over inhospitable terrain. While the ATSB do not dispute the currently published immediate actions, they are predicated on a favourable flight regime for the recovery and the procedure does not appear to cater for an unfavourable flight regime, such as an ‘if, then, else’ procedure – or a procedure with an advisory note.
After further consideration, we have decided to draft a Safety Notice to address the topic of power-limited operations. We feel that it would take a few paragraphs to properly address the topic, more than what could be provided in a POH procedure. Although the information should be covered during pilot training, a Safety Notice could help those pilots who normally do not find themselves in power-limited situations.
After further consideration, we have decided to draft a Safety Notice to address the topic of power-limited operations. We feel that it would take a few paragraphs to properly address the topic, more than what could be provided in a POH procedure. Although the information should be covered during pilot training, a Safety Notice could help those pilots who normally do not find themselves in power-limited situations.
RHC have had multiple internal reviews of various Safety Notice drafts. The common feedback was that low-RPM recovery is unrelated to minimum-power airspeed. Our former chief instructor noted that power required vs airspeed is a topic that is well covered during instruction. We were unable to create a Safety Notice that we thought would have a significant safety impact. Therefore, we do not intend to issue anything at this time.
