The auxiliary power unit (APU) in the tail section of an Air India Airbus A321 (TV-TVG) caught fire at Delhi airport on Tuesday, just as passengers were disembarking after arriving from Hong Kong. The aircraft, carrying around 170 people, sustained damage, but fortunately, all passengers and crew were unharmed.
An Air India spokesperson stated, “Flight AI 315, operating from Hong Kong to Delhi on July 22, 2025, experienced an APU fire shortly after landing and parking at the gate. The incident occurred during disembarkation, and the APU was automatically shut down as designed.” The airline has reported the incident to aviation authorities, and sources suggest a possible maintenance issue as the cause.
The aircraft sustained some damage, but all passengers and crew disembarked safely. The plane has been grounded for further investigation, and aviation authorities have been notified.
As explained by aviation website Skybrary, the auxiliary power unit (APU) enables an aircraft to function independently without external ground support like power units, air-conditioning systems, or air start carts.
The APU is a small jet engine typically housed in the aircraft’s tail cone, though it may also be located in an engine nacelle or wheel well. It can be started using the aircraft’s batteries and supplies electrical power to onboard systems, as well as bleed air for air conditioning and engine startup.
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Globally, there have been instances of APU failures and fires both on the ground and in flight. In June 2016, a fully loaded Airbus A330 of a foreign airline had to be evacuated at London Heathrow after the cabin filled with smoke. Investigations revealed the smoke was caused by a failed APU seal that allowed hot oil to enter the bleed air system.
Similarly, in July 2013, an Air France Boeing 777-300 at Paris Charles de Gaulle Airport was evacuated after passengers detected a burning smell and saw thin smoke in the cabin during boarding.
