A nozzle replacement was carried out one to two days before the incident. Investigators suspect that following the replacement, some nuts were insufficiently tightened, leading to fuel leakage and the fire.
Last week, an Airbus A320 operating the Bengaluru-Delhi flight, with 160 passengers on board, declared a Mayday and made an emergency landing at Delhi Airport after pilots received a fire indication from one of the engines. The indication was subsequently confirmed as true. While the investigation is yet to be concluded, the preliminary findings have raised alarms about whether similar lapses have occurred in other cases.
DGCA has suspended the technician and engineer involved and, as a precaution, has asked Air India to carry out checks on all planes whose nozzles were replaced.
Nuts are fasteners that keep fuel and hydraulic systems sealed during flight. “When fuel leaks into hot engine components, it will automatically cause fire. While connecting a nut, technicians apply torque to fasten it. Maintenance manuals define the precise amount of torque that should be applied. Applying less pressure could cause a leak while more than required pressure could cause deformity,” an engineer said.
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The incident is the latest in a series of engineering lapses that have plagued Air India since the Tata Group took control of the airline in 2022. During privatisation, AIESL, a subsidiary of the airline under government ownership — was kept out of the sale process.Air India’s fleet is older than its rivals and requires more frequent maintenance. While the airline has been building in-house engineering capabilities at major stations and handles line maintenance of narrow-body planes itself, it remains dependent on AIESL for some narrow-body planes and its entire wide-body fleet.
An Air India spokesperson said the incident is under investigation. “We have proactively mobilised and strengthened our in-house engineering and maintenance capabilities, while also optimising available third-party support, to ensure continuity of maintenance activities across the fleet,” the spokesperson said.
The industry is facing a severe scarcity of skilled engineers, which affects the quality of work. Air India and IndiGo have been on a hiring spree as they expand their fleets, making it difficult for the state-owned company to retain experienced technicians.
Hundreds of AIESL technicians have been on strike for the past several days demanding better pay, forcing the company to rope in third-party firms and retired employees for regular maintenance.
“Since these are repetitive tasks, there remains a chance of mistakes. Hence the practice is that after the technician finishes their job, the aircraft maintenance engineer performs an additional cross-check inspection, and signs to verify that the task was correctly carried out and in accordance with the maintenance procedures,” the engineer quoted above said.
A senior AIESL official acknowledged that improper workmanship is likely the cause of last week’s fire but insisted their technicians are qualified for the work.
“We are trying to sort out the issue. Already many have joined back. But the lapse is in no way connected to the ongoing strike as we are deploying only those who are qualified as replacement,” the official said.