What happened
During a climb to approximately 650 ft above ground level, the engine of the Robinson R44 (registration VH-OBK) lost power. As the pilot transitioned from a crosswind to a downwind turn following a go-around, they noticed a drop in performance. However, the pilot did not immediately realize that engine power had been lost, partly because multiple radio broadcasts at the time interfered with the ability to detect changes in engine sound or vibration.
While attempting to troubleshoot the performance issues and return to the airport, the pilot passed two suitable locations for a forced landing. When the necessity for an emergency landing became apparent, the pilot targeted a school ground. Due to insufficient altitude, the helicopter could not reach the intended site and instead struck rooftops. Despite the impact, the pilot maintained control of the rotor RPM and the aircraft to perform an autorotation into the rooftops, which helped ensure the survivability of the occupants.
The investigation
Investigators examined the engine and airframe to determine the cause of the power loss. A review of the engine manifold pressure showed levels significantly higher than expected for the ambient conditions, and the descent distance was consistent with an autorotation. A visual inspection of the engine shroud and cooling fan revealed no rotational damage, which further suggested the engine was not producing power at the time of the incident.
While the investigation confirmed the engine was not producing power, a detailed examination of the engine and airframe was not conducted. Consequently, the specific reason for the engine power loss could not be identified. There were no reported mechanical faults prior to the event, and the aircraft had adequate fuel levels.
Findings
- The engine power loss occurred at a low altitude over a densely populated area, creating a difficult scenario for the student pilot.
- The pilot's failure to immediately recognize the loss of power reduced the available options for a safe landing.
- The pilot did not identify a nearby football oval as a landing site, potentially because it was obscured by the instrument panel or airframe.
- The aircraft's descent profile appeared shallower than a typical autorotation because the pilot pitched the aircraft up to reduce airspeed from 70–80 kt to a target of 55 kt.