What happened
On May 3, 2020, an Airbus Helicopters AS350 B3, registration N1WT, performed an emergency landing at Airglades Airport (2IS) in Clewiston, Florida. The flight, operated by MACNEIL AVISEATION LLC, originated from Fort Lauderdale Executive Airport (FXE) with a stop at Palm Beach County Park Airport (LNA) before proceeding to the destination.
While entering the left downwind for runway 13 at 2IS, the pilot experienced a sudden increase in pedal resistance, describing the pedals as feeling "rock hard." Simultaneously, the "HYD2" and "SERVO" caution lights illuminated on the warning panel. The pilot also observed light smoke and a burnt odor inside the cockpit, prompting him to open the window. The pilot executed a shallow approach and completed a run-on landing at the airport. There were no injuries and the helicopter sustained no substantial damage.
The investigation
Post-landing inspections of the aircraft revealed that the HYD2 belt had fractured, with significant wear noted on the belt grooves. Remnant belt material was found on the HYD2 pump pulley and the transmission deck. The pulley grooves showed signs of overheating, and the HYD2 pump pulley and its bearing could not be rotated freely by hand.
Components were sent to the Airbus Helicopters materials laboratory in France. Investigators found that the pulley bearing's visible surfaces were thermally discolored. Internal examination of the bearing revealed smearing damage on the pulley's inner diameter and longitudinal scratches on the bearing's inner ring. The bearing's internal components—including the rings, cage, and rolling elements—showed black residue from thermally degraded grease, as well as plastic deformation and cage material transfer.
Testing revealed that if the pulley is not heated to approximately 110° Celsius during installation, the bearing can be installed skewed. A test installation performed without preheating resulted in a skewed bearing and similar smearing damage to the pulley.