SINGAPORE – Transport safety investigators have found that damage to wires and cable insulation, and the presence of liquid in a Singapore Airlines (SIA) in-flight entertainment (IFE) frame, likely contributed to a smoke and fire incident in the air about a year ago.

A flight attendant had to use three fire extinguishers on the IFE panel during a flight from Tokyo to Los Angeles on March 27, 2023.

No one was reported injured in the incident.

In a report published on March 12, 2024, the Ministry of Transport’s Transport Safety Investigation Bureau (TSIB) said that smoke and fire were seen at an IFE panel on the Narita-Los Angeles flight.

The incident happened at about 11.15am local time (2.15am the next day Singapore time), as the plane was approaching Los Angeles.

The Boeing B777-300ER had 234 people on board at the time.

According to the report, a passenger in seat 48K alerted the cabin crew when he noticed smoke coming out from the IFE panel directly in front of him.

It is noted that before the plane took off at Narita Airport, the passenger had tried to charge his laptop using a USB port on the panel, but unplugged his device after realising it was not charging.

He did not use any of the USB ports for the rest of the flight.

Reacting to the smoke, a flight attendant immediately cut the power supply for all three IFE panels in the same row of seats. Another attendant also alerted the flight crew.

The report said a flight attendant used two fire extinguishers when sparks were seen on the panel.

Meanwhile, the passengers in the two affected rows – 47 and 48 – were moved elsewhere, while a flight attendant stationed himself near the affected panel.

The plane was scheduled to land in Los Angeles at 12.50pm.

The report said that after the aircraft had just touched down on the runway, the same flight attendant had to use a third fire extinguisher after noticing smoke, electrical sparks, and a “lighted flame” coming from the same in-flight panel.

Smoke was also coming from the bottom of the seat where the affected IFE panel was attached. Another flight attendant then turned off the power to all the IFE panels on board the aircraft.

SIA had noted that a multi-port jack (MPJ) panel of seat 41K in the same aircraft had emitted smoke four days before the flight, according to the report.

The seat was six rows directly ahead of seat 47K with the smoking panel on the flight of March 27, 2023, and the affected parts were replaced.

Investigators said that the MPJ is part of the IFE panel. The MPJ comprises two USB ports and an iPod connector.

Following the March 27, 2023, incident, SIA checked the aircraft’s electrical system for the IFEs and found previously undetected damage to the wires and cable insulation at yet another seat – 41H.

The damage resulted in a short circuit where the power supply for seat 41H’s IFE unit was unintentionally connected to all the other IFE units within the cabin column, according to the report.

This and the presence of a liquid on the IFE frame combined to cause overvoltage and heat damage in the entertainment unit on the March 27, 2023, flight, according to the report.

Investigators noted that the manufacturer of the IFE, which was not named in the report, had issued two modifications to address the overvoltage in the MPJ.

The manufacturer had recommended that faulty units be replaced with modified ones.

Following the incidents, the manufacturer recommended checks on the cable harness in the seats’ armrest every five to seven years for signs of incorrect or degenerated cable routing, or connections that could lead to cable damage.

A cable harness is an assembly of electrical wires that transmits electrical power in an aircraft.

In the report, the TSIB recommended that SIA replace the MPJs on its Boeing 777 fleet with modified units.

“SIA notes the findings by Singapore’s Transport Safety Investigation Bureau. SIA conducts periodic checks on the cable harness as recommended, and also replaced the multi-port jacks and cable harness where necessary,” an SIA spokesperson said, adding that the MPJ replacements had the recommended modifications.

“The safety of our customers and staff is always our No. 1 priority,” the spokesperson added.

Associate Professor Sanjib Kumar Panda, of the NUS College of Design and Engineering’s department of electrical and computer engineering, said that a faulty connection or damaged wire can cause electrical current to travel along the wrong route and damage an electrical device.

He also added that liquids are a good conductor of electricity, and they can cause a short circuit leading to high current. Excessive heat generated from a short circuit would result in smoke and fire. 

Mr Michael Daniel, managing director of consultancy Aviation Insight, said incidents involving smoke or fire in an aircraft are not common, adding that any such incident is “very serious”.

“If the fire and smoke are allowed to propagate, it could lead to a catastrophic event. At a minimum, the pilots would declare an emergency and land at the nearest suitable airport,” he said.