What happened
On December 14, 2017, at approximately 12:50 local time, a Robinson R66 helicopter was undergoing maintenance procedures at EPPK Kobylnica. The pilot initiated a ground start of the aircraft's engine to prepare it for storage. According to Rolls Royce technical guidelines, the installed engine could remain stored for up to 45 days without needing to be run again after a successful test.
During the startup sequence, the exhaust gas temperature (EGT) rose sharply beyond the maximum allowable limit of 920°C. The pilot immediately aborted the start procedure. Subsequent data retrieval from the Engine Monitor Unit (EMU) confirmed that the EGT had spiked to approximately 947°C for a duration exceeding one second. Due to this excessive heat event, the manufacturer recommended that the engine undergo service procedures at an authorized facility.
The investigation
The incident was recorded in the Aircraft Technical Log (PDT), and fault data from the EMU was extracted and printed as evidence. The investigation focused on verifying the parameters recorded during the faulty start and determining the cause of the temperature spike. The helicopter remained grounded and unserviceable pending engine service.
Findings
The primary cause of the incident was determined to be an incorrectly executed startup procedure. The pilot failed to adhere strictly to the prescribed steps for initiating the engine, resulting in the excessive exhaust gas temperatures that necessitated the abort.
Safety action
Following the incident, the operator conducted a debriefing with the pilot. Special emphasis was placed on reviewing and reinforcing the correct procedures for starting the Robinson R66 helicopter to prevent recurrence.