Draft:Air India Flight 829

Air India Flight 829 was an international passenger flight operating from Chhatrapati Shivaji Maharaj International Airport to King Khalid International Airport. On 4 September 2009, the Boeing 747-437 operating the flight caught fire on one of its engines while taxiing towards the runway for takeoff. The crew halted the aircraft and evacuated everyone on board of whom 21 were injured during the evacuation. After assessing the damage, the aircraft was subsequently written off.

It was determined that the heavy fuel leak led to a fire that resulted from the complete dislodging of the coupling in the No.1 strut fuel feed line. The reason for this dislodging was the failure of the tie wire hole and the subsequent dislodging of the tie wire. As a result, the leaked fuel fell onto engine No.1, the outermost left engine, and caught fire.

As of April 2024, Air India now uses AI829 as a service between Dehli—Thiruvananthapuram. The airline utilizes an Airbus A320 on this route.

Background
Air India Flight 829 was originally scheduled to depart Mumbai at 02:00 Indian Standard Time (or IST). However, the aircraft previously assigned for this flight returned to the gate due to a technical problem. After the SNAG rectification, the plane departed the gate, but the SNAG warning reappeared, and the plane again returned to the gate around 06:00 IST. The passengers were then deplaned, the delay was extended to 10:45, and VT-ESM, the aircraft involved in the incident, was assigned to perform the flight with a delay of more than eight hours. After all the passengers and crew reboarded the aircraft, at around 10:48 IST, since VT-ESM was without a serviceable auxiliary power unit (APU), according to Minimum Equipment List (MEL) requirements, engine No. 4, the outermost right engine, was started before pushback. After some air traffic control, or ATC for short, delays, the pushback commences at around 10:49 IST. However, the tow bar fails after pushing back the aircraft 8-10 feet. After authorizing a new tow bar, the pushback was complete with the aircraft facing Eastwards. Immediately after, the flight crew starts the three remaining engines in a sequence.

Aircraft and crew
The aircraft involved in the incident was a Boeing 747-437, registered as VT-ESM. The plane had its maiden flight on 2 July 1993 and was delivered to the airline on 4 August. The aircraft had logged on to 59225 airframe hours and was equipped with four Pratt and Whitney PW4056 engines.

Flight 829's captain was 58-years-old and, at the time of the incident, he had logged more than 12838 hours of flying time, 4821 of which were on the Boeing 747. His co-pilot, aged 63, had logged more than 12593 hours of flying time, including 4520 on the 747.

Incident
The aircraft begins taxiing at around 10:54 IST and soon turns right to taxiway G. While taxiing, the crew of a company aircraft docked on Gate 95, sees fuel gushing out of engine No.1 on the left wing of the Boeing 747. Then the crew informed the dispatcher on the company channel about the fuel leak. The company crew, however, could not contact Flight 829 because they were on the ground frequency whereas the 747 has their frequency tuned in to the tower frequency. The dispatcher calls the flight crew of Flight 829 about the fuel leak. However, the company channel is switched to the off position by the operating crew since it creates unwanted disturbance during briefing and taxi/takeoff clearances. This is not in the company's operating procedures. Still taxiing on Taxiway G, an engineer assigned to another company's aircraft noticed the fuel leak coming from the No. 1 engine of the aircraft. Without hesitation, the engineer took off his ramp jacket and began signaling to the aircraft. Although the Cabin Crew In-Charge (CCIC) saw the person signaling, she was unable to determine the reason and therefore disregarded it. A follow-me jeep somewhere in the area also noticed the fuel leaking from the aircraft and it instantaneously informed the ATC about the situation. The follow-me jeep was only able to provide the registration number of the aircraft to the ATC. As the aircraft turned onto taxiway A3, the ATC called out for VT-ESM twice but received no response from the aircraft. Finally, the ATC called out AI829 to verify the registration as ESM, which was confirmed by the crew. Once the registration was confirmed, the ATC informed the flight crew about the major fuel leak and ordered them to immediately switch off their engines. The captain halted the aircraft and began the emergency procedure checklist. By this time, however, engine No.1 already caught fire and was now progressing toward engine No.2. Then the CCIC spotted the fire and acted swiftly by issuing evacuation commands on the PA system, instructing passengers to evacuate from the right side of the aircraft. At the same time, the passengers became aware of the fire outside the cabin windows and immediately began rushing towards the exit doors. As the passengers evacuated using the escape slides, 21 of them sustained minor injuries. Once it was confirmed that no one was left onboard, the CCIC evacuated the aircraft. Interestingly, both pilots evacuated directly from the cockpit and didn't come down to the lower deck during the evacuation. In fact, they left the aircraft before the evacuation was complete. The left wing of the aircraft suffered fire damage to its leading and trailing edges, along with engine No.1 and pylon. The damage to engine No.1 was found to be substantial due to the fire.

Investigation and changes
India's Directorate General of Civil Aviation (DGCA) released their final report, concluding that the probable cause of the incident was the complete dislodging of the No.1 strut fuel feed line coupling, which was caused by the dislodging of the tie wire from the failed tie wire hole. This dislodging then resulted in a heavy fuel leak. Even though the pilots had switched off their engines, the leaked fuel fell onto the hot engine No.1 setting a fire. The pilots' failure to detect the fuel leak during the walk-around inspection, as well as the lack of situational awareness and crew coordination, were some significant factors that contributed to the incident. According to investigators, the issues with AI829 actually began much earlier than the incident itself. Flight 829 was scheduled to depart at 02:00, but was delayed by 2 hours and 30 minutes due to technical problems. The original aircraft assigned to the flight began to taxi for take-off but had to abort shortly after due to the same issues, as a false fire alarm had gone off in the cockpit. Upon inspection, engineers discovered water in the cargo compartment that triggered the alarm. The flight was eventually delayed until 10:45, and another Boeing 747, VT-ESM (the aircraft involved), was assigned to operate the flight. Following the incident, the DGCA instructed Air India to assess its maintenance programs and practices and to conduct frequent and effective inspections to identify any potential fuel leaks in its aircraft.