Communication Breakdown; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
General None Reported / Taken
Human Factors; Procedure
Flight arrived on blocks at XA:00; the arrival onto [maintenance] bay procedures were normal. I was in the process of my aircraft walk around check and our C Mechanic had completed the oil service on right engine. At XB:05 I was near the nose gear and the C Mechanic was up on a high stand carrying out oil service on left engine when I heard an engine starter starting up. I turned toward the left engine to see it cranking over. I moved quickly to get the C Mechanic's attention for him to get down off the stand. The refueller was also at the engine with his truck attached to the aircraft and 3 security guards were located 5 meters behind the engine on their way to check the bulk cargo loaders and catering staff.After getting their attention and clearing the area I went straight to the headset at the nose gear to call the flight deck and get their attention.My first call to the flight crew was 'shut the left engine down.' Their response was 'it's not going.'My response was 'the left engine is cranking; shut it off.' Their response 'No? Fuel is not on.'My final call to them was 'listen; the left engine is motoring; the start switch is on start or crank; turn it off.'Their response was 'engine is secured.' And that was the only response I received from them.
Maintenance reported that while servicing the engine oil on a Boeing 787; it sounded like someone attempted to start the engine.