Fuel to Air India jet engines cut off moments before crash: Preliminary report
The Boeing 787 Dreamliner immediately began to lose thrust and sink down, according to the report released on Saturday (Jul 12) by Indian aviation accident investigators.
One pilot can be heard on the cockpit voice recorder asking the other why he cut off the fuel. "The other pilot responded that he did not do so," the report said.
It did not identify which remarks were made by the flight's captain and which by the first officer, nor which pilot transmitted "Mayday, Mayday, Mayday" just before the crash.
At the crash site, both fuel switches were found in the run position and the report said there had been indications of both engines relighting before the low-altitude crash.
Both pilots were experienced jet pilots with about 19,000 total flying hours between them, including more than 9,000 on the 787.
The preliminary report also does not say how the switch could have flipped to the cutoff position on the Jun 12 London-bound flight from the Indian city of Ahmedabad.
US aviation safety expert Anthony Brickhouse said a key question is why were the switches moved in a way that is inconsistent with normal operations.
"Did they move on their own or did they move because of the pilots?" he asked. "And if they were moved because of a pilot, why?"
US aviation safety expert John Cox said a pilot would not be able to accidentally move the fuel switches that feed the engines. "You can't bump them and they move," he said.
Flipping to cutoff almost immediately cuts the engines. It is most often used to turn engines off once a plane has arrived at its airport gate and in certain emergency situations, such as an engine fire. The report does not indicate there was any emergency requiring an engine cutoff.
"At this stage of investigation, there are no recommended actions to Boeing 787-8 and/or GE GEnx-1B engine operators and manufacturers" India's Aircraft Accident Investigation Bureau said.
Air India, Boeing and GE Aerospace did not respond immediately to requests for comment.
The agency, an office under India's civil aviation ministry, is leading the probe into the world's deadliest aviation accident in a decade.
The plane's two black boxes, both combined cockpit voice recorders and flight data recorders, were recovered in the days following the crash and later downloaded in India.
Black boxes provide crucial data such as altitude, airspeed and final pilot conversations, which help in narrowing down possible causes of the crash.
Most air crashes are caused by multiple factors, with a preliminary report due 30 days after the accident according to international rules, and a final report expected within a year.
Air India has been under intense scrutiny since the crash.
The European Union Aviation Safety Agency said it plans to investigate its budget airline, Air India Express, after Reuters reported the carrier did not follow a directive to change engine parts of an Airbus A320 in a timely manner and falsified records to show compliance.
India's aviation watchdog has also warned Air India for breaching rules for flying three Airbus planes with overdue checks on escape slides and in June warned it about "serious violations" of pilot duty timings.
The US National Transportation Safety Board declined to comment on the release of the report.
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CNA
11 hours ago
- CNA
Pilot error or technical fault? Air India crash report deepens mystery of fuel supply cut
SINGAPORE: Air India flight AI171 crashed in June because the plane's fuel control switches were moved to cut-off position, starving the engines of fuel, according to a preliminary report on the deadly disaster. The report explains why the Boeing 787-8 Dreamliner went down moments after taking off from Ahmedabad airport. But it raises questions as to how the fuel supply to both engines could have been cut off, given the design of these controls. In a cockpit voice recording, one pilot is heard asking the other why he flipped the switches. The pilot responds that he did not do so. The plane was seen losing altitude. Seconds later, the fuel switches were flipped to turn the fuel supply back on. But it was too late to stop the plane's descent. It crashed into a medical college hostel, killing all but one of the 242 people on the plane. More than 30 people on the ground also died. The preliminary report, issued by India's Aircraft Accident Investigation Bureau on Saturday (Jul 12), showed that the crash was unlikely to have been caused by pilot error, said aviation experts. Fuel control switches are not like light switches, which can be turned off and on accidentally when you hit them, Mr Chow Kok Wah, a former airline executive in aircraft maintenance, told CNA. 'It's a metal switch with a knot sticking out. You have to pull the switch and lift it up over a metal obstacle, and then release it back in,' he explained. 'There's no way that you can accidentally knock it and then it goes in the opposite direction.' Mr Eshan Khalid, a former pilot and aviation expert, told Reuters 'deliberate action' was needed to move the fuel control switches. The pilot's exchange in the audio recording also showed that there were attempts to move the switch back to "run" mode. 'From the findings, it tells me that it wasn't pilot error,' said former pilot Marco Chan, a senior lecturer at Buckinghamshire New University's aviation school. 'And there's nothing, at least for now, for the time being, that points to a pilot error from the cockpit voice recorder. It appears they are trying to recover the flight from going down to the ground.' Timeline of events Here's a detailed timeline of what happened aboard AI171 moments before the crash: 7.55.15am GMT: The aircraft requested taxi clearance, which was granted by air traffic control. A minute later, the aircraft taxied from the bay to Runway 23 via Taxiway R4, backtracked and lined up for take-off. 8.02.03am: The aircraft was transferred from ground to tower control. 8.07.33am: Take-off clearance issued. 8.07.37am: The aircraft started rolling. 8.08.39am: Aircraft lifted off. "The aircraft air/ground sensors transitioned to air mode, consistent with liftoff," the report said. 8.08.42am: Aircraft reached max airspeed of 180 knots. "Immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec," the report said. "The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. "In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so. "The CCTV footage obtained from the airport showed Ram Air Turbine (RAT) getting deployed during the initial climb immediately after lift-off "The aircraft started to lose altitude before crossing the airport perimeter wall." 8.08.47am: Both engines' values "passed below minimum idle speed", and the RAT hydraulic pump began supplying hydraulic power. 8.08.52am: Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN. 8.08.56: Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN. "When fuel control switches are moved from CUTOFF to RUN while the aircraft is in flight, each engine's full authority dual engine control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction," the report stated. "Engine 1's core deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to relight but could not arrest core speed deceleration and reintroduced fuel repeatedly to increase core speed acceleration and recovery." 8.09.05am: One of the pilots transmitted 'MAYDAY MAYDAY MAYDAY". 8.09.11am: Data recording stopped. 8.14.44am: Crash fire tender left the airport premises for rescue and firefighting. 'TRICKY THING' Mr Chan told Reuters that the report pointed to a chip malfunction. He believes the cutoff came from an error with the chip, for which the engine manufacturer previously issued a service bulletin advising maintenance in order to prevent signal loss. "Once you have a loss of signal, the fuel isn't commanded, ... then there's no fuel going to the engine, which seems to have matched what the service bulletin was saying with this current investigation," said Mr Chan. However, Mr Kwok said a chip malfunction was 'very unlikely'. The fuel control switches are a very crucial function in the operation of a plane, and whoever designed them would have thought of all these possibilities, he added. '(They) would not have designed it in a way that a malfunction could cause the engine to shut down, because it's a very, very serious matter,' said Mr Kwok. 'And the fact that it happened to two engines almost simultaneously would put the probability at near zero.' He also noted that, according to the report, the engines had responded positively after the pilots noticed the switches' position and changed them back. 'If it were a malfunction, would it come on again? Both of them?' he asked. 'It's very, very, very unlikely.' Asked what else could have caused the switches to move, Mr Kwok said it was a 'tricky thing'. 'All we can say is somebody operated the switch. It will not move on its own.' Warning against speculation that the pilots could be responsible, Mr Khalid raised the possibility that some clarification might be needed from the Aircraft Accident Investigation Bureau as an explanation. It is not clear from the short exchange between the pilots if they were referring to the switch position or the engine states. Their exact words were not stated in the report, which summarises the events. 'Maybe it (the bureau) will clarify in due course of time that it was not the fuel cutoff switch, but the fuel shutoff valve that probably switched off while the fuel cutoff switch continued to remain in its position," Mr Khalid suggested to Reuters. REPORT GIVES BASIC INFORMATION The preliminary report found no mechanical or maintenance faults on the Air India Boeing Dreamliner, and that all required maintenance had been carried out. Asked if there should be more checks on fuel control switches given the lack of answers on how the controls moved, Mr Kwok pointed out that the authorities and manufacturers had not yet issued any guidance. There has been no factual evidence to support the conclusion that immediate action was needed to be taken on similar planes, he added. Mr Kwok also noted that in aviation investigations, the preliminary report only serves to provide the public with some basic facts to prevent unnecessary speculation. Now that the report has been released, a more thorough investigation will take place before a final report, he said. The authorities and manufacturers will likely look at the plane's engine start system once more. 'A month is a bit hard for them to do all that stuff,' Mr Kwok said. Should they find nothing, the investigators will then look at other possibilities, such as the background and behaviour of those in the cockpit, he added. "Now the focus is entirely on the start switch. And if the start switches are working properly, then it must be (that) somebody moved it,' he said. 'Who, is the question.'
CNA
15 hours ago
- CNA
Air India crash: What happened in the lead up to the disaster?
Scroll up for the next video X Air India crash: What happened in the lead up to the disaster?
AsiaOne
2 days ago
- AsiaOne
What are the fuel switches at the centre of the Air India crash probe?, Asia News
NEW DELHI - The preliminary report from investigators probing the Air India crash that killed 260 people showed that seconds after takeoff, the Boeing 787 plane's engine fuel control switches were switched off briefly, starving them of fuel. Below are a few facts about the switches, their functions in the aircraft and their movements on the Air India flight. What are fuel switches? They are switches that regulate fuel flow into a plane's engines. They are used by pilots to start or shut down engines on the ground or to manually shut down or restart engines if an engine failure occurs during a flight. Aviation experts say a pilot would not be able to accidentally move the fuel switches that feed the engines. But if moved, the effect would be immediate, cutting off engine power. There are independent power systems and wiring for the fuel cutoff switches and the fuel valves controlled by those switches, according to US aviation safety expert John Cox. Where are the fuel switches located? The two fuel control switches on a 787, in Air India's case equipped with two GE engines, are located below the thrust levers. The switches are spring-loaded to remain in position. To change one from run to cutoff, a pilot has to first pull the switch up and then move it from run to cutoff or vice versa. There are two modes: "CUTOFF" and "RUN". What happened on the fatal Air India flight? According to the flight recorder, a few seconds after takeoff, switches for both engines transitioned to "CUTOFF" from "RUN" one after another with a time gap of one second. As a result, the engines began to lose power. One pilot was heard on the cockpit voice recorder asking the other why he cut off the fuel. "The other pilot responded that he did not do so," the report said. It did not identify which remarks were made by the flight's captain and which by the first officer. Seconds later, the switches flipped back to "RUN", according to the preliminary report. Both fuel control switches were found in the "RUN" position at the crash site, it said. When fuel control switches are moved from "CUTOFF" to "RUN" while the aircraft is in flight, each engine's control system automatically manages a relight and thrust recovery sequence of ignition and fuel introduction, the report said. "No sane pilot would ever turn those switches off in flight," especially as the plane is just starting to climb, US aviation safety expert John Nance said. [[nid:719732]]
