Date:	Monday 6 March 2017
Time:
Type:	Boeing 737-524 (WL)
Owner/operator:	UTair Aviation
Registration:	VQ-BJO
MSN:	28910/2972
Engine model:	CFMI CFM56-3
Fatalities:	Fatalities: 0 / Occupants:
Other fatalities:	0
Aircraft damage:	Minor, repaired
Category:	Serious incident
Location:	Leningrad Oblast -   Russia
Phase:	En route
Nature:	Passenger - Scheduled
Departure airport:
Destination airport:
Confidence Rating:	Information verified through data from accident investigation authorities

Narrative:
The crew forgot to turn off the APU (Auxiliary Power Unit) before takeoff. During the flight, while descending for landing, the "APU Fire" alarm was triggered. Upon inspection after landing, signs of fire were found in the APU compartment.
The most probable cause of the fire in the auxiliary power unit on the aircraft is a fuel leak from the combustion chamber, which led to the ignition of the APU due to its being left on. The cause of the fuel leak from the APU's combustion chamber is the improper sealing of the injector's connection with the combustion chamber.

Analysis of the state of flight safety in the civil aviation of the Russian Federation in 2017

Date/time	Contributor	Updates
25-Aug-2024 18:05	ASN	Added