What happened
On February 6, 2017, a professional helicopter crew was performing a repositioning flight from Szczecin (EPSC) to Ostrowo Wiellamopolskie (EPOM) via Poznań (EPPO) under an operational order for LPR. The flight was conducted in two segments: the first leg from Szczecin to Poznań was flown under IFR conditions for training purposes, while the second leg from Poznań to Ostrowo Wielkopolskie was conducted under VFR rules.
While operating in the Sieraków region, the crew initiated a descent procedure using VOR DME toward the runway in use at Poznań, with no intention of landing. During the maneuver to level off from the descent while simultaneously executing a right turn toward the course for EPOM, the pilot observed a yellow indication on the FLI (Flight Limiter Indicator) signifying that engine torque (TRQ) values had exceeded permissible limits. The pilot responded by reducing the collective pitch and power. The flight continued to the destination, landing in Ostrowo Wielkopolskie without further incident.
The investigation
An analysis of the UMS/PGS system recordings confirmed that the torque on the right engine had exceeded limits. Specifically, the torque exceeded the threshold for a duration of 2.125 seconds. According to established maintenance procedures (MSM 05-51-00,6-8), this excursion was classified as a Category B event, necessitating specific maintenance actions within 5 flight hours.
On February 7, 2017, technical personnel performed the required inspections, which included checking the oil filter, the main gearbox and fenestron chip detectors, and the main rotor shaft hub. Following these inspections, a ground test was conducted, and the aircraft was found to be airworthy.
Findings
- The right engine torque exceedance was caused by excessively aggressive use of the flight controls during the transition from the descent maneuver into a simultaneous right turn toward the approach path for Poznań.