| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. Because occurrence briefs are not investigations under the Transport Safety Investigation Act 2003, the information in them is de-identified. |
What happened
On 22 June 2024 at about 0915 local time, a Robinson R44 was conducting a scenic flight with a pilot and 2 passengers onboard, over the King Leopold Ranges, Western Australia. While in a slow downwind cruise of 30 kt at about 500 feet above ground level, the pilot detected a loss of tail rotor effectiveness as well as a loss of rotor RPM. They attempted to correct and continue flight, however were unable to maintain height and performed an emergency landing over rocky terrain. The helicopter landed flat on both skids, however skidded down a slope on the left side and rolled to the left, impacting a rock ledge. The helicopter was substantially damaged (Figure 1).
Figure 1: Helicopter accident site
Safety message
Pilots are reminded of the effect of density altitude on aircraft performance. Robinson Helicopter Company (RHC) pilot operating handbooks provide performance charts to assist pilots with planning flights. These include a density altitude chart and out-of-ground effect hover ceiling chart to provide an expectation of aircraft performance during flight. Operators are encouraged to conduct periodic reviews with pilots on aircraft performance and limitations in a range of weather conditions.
Pilots must be prepared to respond immediately to a low RPM warning and ensure they are familiar with the power curve and associated airspeeds for their particular helicopter.
RHC advises pilots of their piston-engine helicopters to roll on the throttle while lowering the collective lever and, during forward flight apply aft cyclic as per the low RPM recovery procedure.
The RHC website provides training videos for higher risk flight conditions, including several presentations on rotor energy management which could be beneficial to pilots during their initial training, upgrades and flight reviews.
Pilots are encouraged to review low RPM rotor stall RHC (SN-24), aerial survey and photo flights RHC (SN-34) and unanticipated yaw RHC (SN-42) in the Robinson Helicopter Company Safety Notices.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.