Incident Description
While performing a hovering autorotation, as the helicopter touched down, the certified flight instructor (CFI) heard a loud snap emanating from the right side. The CFI immediately took control from the student pilot and attempted to neutralize the anti-torque pedals, but found them stuck in place, with the right pedal in the forward position. He reduced the engine revolutions per minute to 75 percent and tried to move the pedals without success. At that point, he instructed the student to initiate shutdown procedures.
Inspection Findings
Following a normal shutdown, both the CFI and the student exited the helicopter and inspected the cause of the stuck anti-torque pedals. They observed a broken metal structure adjacent to the restraining block that retains the anti-torque pedals. The CFI reported that the break appeared to be in the actual metal structure to which the entire pedal assembly is bolted. Further inspection revealed that the right-hand support bracket (part number A359-2) of the tail rotor control system had failed. The operator reported that the airframe had accumulated a total of 13,000 hours in service.
Manufacturer Response
The helicopter manufacturer stated that they had been aware of other instances of failed support brackets on helicopters with over 7,500 hours in service. In response, the manufacturer increased the thickness of the support bracket material and changed their overhaul procedures to require replacement of the A359-1 and A359-2 support brackets at overhaul for all R22 and R44 models. Additionally, the manufacturer issued service bulletin SB-97 for the R22 and SB-63 for the R44, which mandate the installation of a safety tab on older, thinner support brackets.