Event Details
On April 8, 2018, at approximately 11:35 local time, a helicopter EC 135P2+ landed at the LPR Lublin Radawiec base after completing rescue mission number 69/R7/2018. The pilot, a professional helicopter pilot, began the engine shutdown procedure. After moving the engine mode switch on panel 20VE from the IDLE position to OFF, the pilot observed that the right engine continued to run. The FLI monitor indicated right engine rotational speed at approximately 10%, and the CAD monitor displayed a "IDLE" caution. The pilot then decided to shut down the engine using the emergency procedure. By turning the right engine twist grip to the right and pressing the emergency stop button, the engine stopped. The pilot made an appropriate annotation in the helicopter's technical log.
Technical Findings
Following the incident, the helicopter was grounded, and the Technical Coordination Center was notified. Consultations were held with the engine manufacturer Pratt & Whitney Canada Corp. and the helicopter manufacturer Airbus Helicopters. On April 9, 2018, a technician from the Warsaw Babice maintenance station performed inspections according to AMM 71-00-00, 6-1, including checking fuel lines for leaks (no issues), a cold start test (no issues), and a boroscope inspection of the hot section, turbine blades, and combustion chamber (no issues). Additionally, the 20VE block was replaced with a new one, and functional tests were conducted per AMM 31-11-20,55 and AMM 31-11-20,51 without starting the engine, with no anomalies found. Because the manufacturer could not definitively identify the 20VE block as the cause, an additional question was posed regarding whether the FMM fuel valve could be responsible for incomplete fuel cutoff when the engine mode switch was set to OFF. The manufacturer stated that they could not exclude the possibility that the FMM fuel valve might have contributed to the failure to shut down.
Probable Cause
The probable cause of the incident was a malfunction of the 20VE block or a temporary malfunction of the FMM fuel valve.