What happened
On March 19, 2015, a Mi-2 Plus helicopter was performing a repositioning flight from EPBC airport to the Brynek landing site. The flight was intended to take approximately 2.5 hours following the completion of technical test flights.
During the final phase of the flight, the pilot observed that the main rotor tachometer needle had dropped to the zero position. Upon noticing this discrepancy, the pilot increased monitoring of other engine and transmission parameters and began listening closely for any unusual noises from the main gearbox or the main rotor. Despite the loss of the RPM reading, the pilot noted that the aircraft's handling, engine parameters, and operational sounds remained normal. Relying on extensive flight experience, the pilot decided to continue to the destination, which remained within visual range. The aircraft landed at Brynek without further incident.
The investigation
The investigation focused on determining why the rotor RPM indication failed. Following the landing, the tachometer and its associated transmitter were removed from the aircraft and sent to the technical department of the operator, LPU "Heliseco," for examination.
Findings
- The loss of main rotor RPM indications was caused by a mechanical defect in the tachometer and a simultaneous failure of its transmitter.
Safety action
Following the incident, the operator implemented several preventive measures:
- A safety bulletin describing the event was issued.
- The incident was reviewed during periodic pilot training regarding Safety Management System (SMS) policies.
- Flight training for Mi-2 pilots was updated to emphasize the ability to identify correct engine and transmission sounds as a secondary means of monitoring aircraft health.