New Delhi: The auxiliary power unit (APU) of an Air India Airbus A321 (TV-TVG), located in the tail section, caught fire at Delhi’s Indira Gandhi International Airport when passengers were disembarking after its arrival from Hong Kong on Tuesday. The aircraft, which had around 170 people on board, was damaged, but the passengers and crew were unhurt. The airline reported the incident to regulator Directorate General of Civil Aviation. Sources say this could be a maintenance issue.An AI spokesperson said, “Flight AI 315, operating from Hong Kong to Delhi on July 22, 2025, experienced an APU fire shortly after it landed and parked at the gate. The incident occurred while passengers began disembarking, and the APU was automatically shut down as per system design. There was some damage to the aircraft; however, passengers and crew members disembarked normally and are safe. The aircraft has been grounded for further investigations, and the regulator has been duly notified.“According to aviation website Skybrary, APU allows an aircraft to operate autonomously without reliance on ground support equipment such as a ground power unit, external airconditioning unit or a high-pressure air start cart. “APU is a small jet engine, which is normally located in the tail cone of the aircraft, but, in some cases, is located in an engine nacelle or in the wheel well. APU can be started utilising only the aircraft battery(s) and, once running, will provide electrical power to aircraft systems as well as bleed air for AC and for engine start,” the website says.There have been instances of APU failure or fire both on the ground and in flight globally. In June 2016, the cabin of a fully loaded Airbus A330 of a foreign airline on the ground at London’s Heathrow Airport was engulfed with smoke, and an emergency evacuation was initiated. Investigation found that the smoke was caused when an APU seal failed and hot oil entered the bleed air supply.In July 2013, passengers boarding an Air France Boeing 777-300 at Paris CDG felt a burning smell, followed by thin smoke in the cabin. The aircraft was evacuated.
