What happened
On 14 April 2009, a Robinson R44 II helicopter, registration ZS-HFW, was conducting a conversion training flight from George Aerodrome to Mossel Bay Aerodrome. The flight involved a specific training exercise where the hydraulic system was intentionally deactivated.
As the student pilot performed the maneuver, the controls became significantly stiffer due to the lack of hydraulic assistance. While the student managed to maintain a steady hover above the runway 09 threshold for a short period, control was eventually lost. The instructor pilot directed the student to reactivate the hydraulic switch, but the student failed to do so in time, leading to a hard vertical impact with the ground. While both occupants escaped without injury, the aircraft was destroyed.
The investigation
SACAA AIID examined the circumstances surrounding the loss of control and the configuration of the aircraft's cockpit. The investigation confirmed that the weather conditions were clear with minimal wind, and the aircraft had been properly maintained with no mechanical defects reported.
Investigators noted that the hydraulic switch used for this exercise was located exclusively on the student pilot's side of the cyclic control. This placement meant the instructor pilot could not reach the switch to assist in the maneuver. The investigation also reviewed the regulatory status of the aircraft, noting that the regulator permitted its use for training despite the lack of a dual hydraulic switch accessible to both pilots.
Findings
- The hydraulic switch was intentionally deactivated for the training exercise.
- The student pilot experienced increased control stiffness and subsequently lost control of the aircraft.
- The instructor pilot failed to take over control of the aircraft, even though the helicopter remains flyable with the hydraulic system off.
- The aircraft's design prevented the instructor from accessing the hydraulic switch, as it was only accessible to the student.