Event Overview
On 6 June 2017, a Bombardier DHC-8-400 aircraft operated by LOT Polish Airlines encountered difficulties during engine start at Hamburg Airport (EDDH). The aircraft had 72 occupants, none of whom sustained injuries.
Sequence of Events
The first attempt to start engine number 1 failed, as no rise in ITT (Interstage Turbine Temperature) was observed. The flight crew performed the ABORTED ENGINE START checklist. To clear excess fuel, a subsequent engine start was attempted without ignition. The second start also failed, with fuel flow at 80, NH around 17-18%, and ITT at 80°C without further increase. The starter time limits were respected. Spilled fuel formed a puddle that was cleaned up by ground services. Passengers were returned to the terminal. The crew made the appropriate entry in the LDP-60 log, filed an ASR (Air Safety Report), and handed the aircraft over to a technical team dispatched from Warsaw.
Technical Findings
After analyzing the symptoms, the technical team replaced the FUEL FLOW DIVIDER in accordance with AMM 73-11-11 Rev.57. The fault was traced to an internal malfunction of the FMU (Fuel Metering Unit), which caused an excessive amount of fuel to be delivered during start, flooding the engine. The defective FMU was replaced, and an engine run and idle test (IDLE RUN AFTER FMU + FFD R/I) were performed. The engine parameters were found to be normal, and the aircraft was cleared for further service.
Cause
The incident was attributed to an internal fault of the Fuel Metering Unit.
Operator Actions
The event was recorded in the LOT Polish Airlines SMS database and classified according to the operator's criteria. It will be included in safety performance indicators (SPI) monitored under the Safety Management Manual. The faulty FMU was sent to a repair facility for further investigation.