History of Flight
On 23 March 2016 at 0600Z, a Robinson R22 Beta helicopter (registration ZS-HXS) departed from a helipad in front of the control tower at Rand Airport (FAGM), Gauteng Province, South Africa. The pilot, accompanied by a passenger, intended to ferry the helicopter to Newcastle Aerodrome (FANC) in KwaZulu-Natal. The pilot had 90 litres of fuel onboard and estimated the flight duration at about 2 hours. Before take-off, the pilot contacted air traffic control (ATC), received surface data, and was cleared to cross all runways to the south and climb to 6000 feet above mean sea level.
During the initial climb, the pilot observed the “Low RPM” warning light illuminating on the annunciator panel, followed by an audio warning. The pilot stated that he immediately rolled the throttle to increase engine power, pulled back slightly on the cyclic to gain height, and then moved the cyclic forward to increase airspeed. However, the helicopter continued to lose height. The helicopter impacted the ground hard on its skids and rolled over onto its right side. During the impact, the main rotor blades severed the tail boom into pieces. The aircraft came to rest approximately 73 metres from the helipad. The airport’s rescue and firefighting vehicles were dispatched to the scene. Neither the pilot nor the passenger sustained injuries. The helicopter sustained substantial damage.
Investigation Findings
The investigation revealed that the helicopter experienced low main rotor RPM after lift-off. The pilot climbed too early and did not continually monitor the rotor RPM, which decayed a few seconds later. The pilot used an incorrect procedure to restore RPM. According to the Robinson R22 Pilot’s Operating Handbook, the correct response to a low RPM warning is to immediately roll throttle on, lower collective, and, in forward flight, apply aft cyclic. The pilot’s actions—rolling throttle on, pulling back on cyclic, and then pushing cyclic forward—did not match this recommended procedure.
Probable Cause
The helicopter experienced low main rotor RPM after lift-off. The pilot took an incorrect action to restore the RPM.