India’s aviation regulator said inspections found no defect in the fuel control switches of a Boeing 787-8 Dreamliner after pilots reported unusual movement when the engine was being started in London.
The Directorate General of Civil Aviation said the issue was flagged on Air India flight AI132, which operated from London to Bengaluru between Sunday and Monday.
While they were starting the engine, the crew noticed that one of the two fuel control switches did not “remain positively latched in the run position when light vertical pressure was applied”, according to reports.
Only on the third attempt did the switch latch correctly and remain stable. The crew physically verified that it was “fully and positively latched” in the “run” position, and completed the flight “without incident”.
Fuel control switches regulate the flow of fuel to an aircraft’s engines and toggle between “run” and “cutoff”. On the Boeing 787 there are two, one for each engine, and they are designed with a locking feature that requires a deliberate pull to change position.
After landing in Bengaluru, the pilots recorded the observation in their post-flight defect report. Air India grounded the Dreamliner, informed the regulator, and referred the matter to Boeing, saying on Monday it was getting the pilot’s concerns checked on a “priority basis”. A Boeing spokesperson told the BBC they were supporting Air India’s “review of this matter”.
The regulator said post-flight inspections, carried out in line with Boeing’s procedures, found the switches to be serviceable.
“Both left and right switches were checked and found satisfactory, with the locking tooth or pawl fully seated and not slipping from ‘run’ to ‘cutoff’,” it said, adding that when full force was applied parallel to the base plate, the switch remained secure.
No abnormal engine parameters, cautions, warnings, or system messages were seen during engine start at Heathrow or at any point thereafter, it further said.
The regulator noted, however, that if the switch was handled incorrectly it could move. “Applying external force in an incorrect direction caused the switch to move easily from ‘run’ to ‘cutoff’, due to the angular base plate allowing slip when pressed improperly with finger or thumb,” it said, stressing that this behaviour did not indicate a defect when operated according to approved procedures.
Checks were carried out on the switches of the affected aircraft, a replacement unit and a switch from another plane.
“In all cases, the pull-to-unlock force was found within limits,” the regulator said, adding that the inspections were conducted in the presence of its officers.
The regulator subsequently advised Air India to circulate Boeing’s recommended operating procedure for the fuel switches to crew members.
Reuters reported on Tuesday that Air India had begun re-checking fuel switches across its Dreamliner fleet following the pilot’s report. Air India operates 33 Boeing 787 jets.
The airline had earlier said that inspections ordered by the regulator found no issue with the locking mechanism, a position it reiterated this week.
The scrutiny comes amid an ongoing investigation into last June’s Boeing 787-8 crash in Ahmedabad. The London-bound Air India flight crashed less than a minute after take-off, killing 241 of the 242 people on board and 19 on the ground.
India’s Aircraft Accident Investigation Bureau is investigating and a final report is expected in a few months.
A preliminary report released in July said both fuel control switches had moved from “run” to “cutoff” shortly after take-off, causing the engines to shut down. But it did not establish how the movement occurred.
The cockpit voice recorder of the doomed flight captured one pilot asking the other why the switches had been moved, with the other responding that he hadn’t flipped them.
After that report, the US aviation regulator said fuel control switches on Boeing planes were safe.
An aviation consultant and former air accident investigator, Tim Atkinson, told the BBC he trusted the design of the switches. “These switches are designed with one purpose in mind, and that is that they cannot be moved unintentionally. There is no doubt in my mind that the design is good. I would be astonished to find it had some kind of latent defect,” he said.
