Fire crews put out a fire in an Air India's plane at Delhi airport on April 24. <br /><br />The fire started at Auxiliary Power Unit (APU) of the plane and was doused immediately. <br /><br />The APU is the smallest engine on an aircraft and is situated at the tail of it. It provides the necessary power to start the main engines.<br /><br />Air India called it a minor incident and said the plane was empty at the time of repair work. <br /><br />The aircraft was bound for a flight to San Francisco that has been postponed, tweeted Air India.<br /><br />A spokesperson of the airline said that an engine of the aircraft experienced an auto shutdown during technical inspection.<br /><br />In a statement on April 25, the national carrier said: ''Airport personnel observed black fumes from the APU exhaust and, believing it to be a fire hazard, sprayed APU and part of the fuselage with foam spray.''<br /><br />''There were no traces of any burn or external damage noticed except for the minor oil leaks traces, which was normal.''<br /><br />''An investigation has been launched to find out the causes of the fire.''
