- ATSB investigation identifies a drive belt failure in a fatal accident of a Robinson R22 helicopter.
- R22 pilots and operators need to regularly check drive system for misalignment and abnormal wear.
- Importance reaffirmed of pilot proficiency in autorations in case of a loss of main rotor drive.
Robinson R22 helicopter pilots are being urged to regularly check and maintain their aircraft’s drive system following a fatal accident in North-West Queensland.
While mustering near Julia Creek on 9 May 2011, a Robinson R22 helicopter was flying close to the ground when it lost drive to the rotor system. This resulted in a high rate of descent before the helicopter hit the ground. The pilot, the only occupant of the helicopter, died in the accident.
As a result of the drive failure and operating conditions at the time, the pilot needed to make an autorotative landing from a low altitude and at minimal speed.
The ATSB found that two v-belts that transfer torque from the engine to the rotor system had failed. The damage to the forward v-belt indicated that it had partially dislodged from the drive sheave, resulting in significant damage to the belt. At some point, the v-belt fragmented, compromising the redundancy of the belt-drive system. Once the rear v-belt failed, all drive to the rotors was lost.
As a result of the drive failure and operating conditions at the time, the pilot needed to make an autorotative landing from a low altitude and at minimal speed. Autorotation is a descent with power off—the helicopter’s rotor system continues to rotate at about normal RPM as a result of the air flowing upwards through the main rotor system. There was limited time for the pilot to recognise the condition, respond accordingly and for the autorotation to develop. This resulted in a high rate of descent at impact.
The accident reaffirms the important advice in ATSB safety advisory notice AO-2011-060-SAN-001. The notice highlights the need for R22 helicopter pilots and operators to pay careful attention to the installation, maintenance and inspection of drive belts and other components of the helicopter’s drive system.
The accident also highlights the importance of pilot proficiency in autorotations during emergency situations. When performing autorotations, there are a number of factors that must be considered in planning and execution to achieve a successful outcome. The ATSB Research and Analysis Report into Helicopter Accidents 1969–88 includes useful information on the risks associated with autorotations.
Read the report: Collision with terrain - Robinson R22 Beta II, VH-DSD, 85 km north-west of Julia Creek, Queensland, on 9 May 2011