Federation of Indian Pilots (FIP) has addressed a technical letter, backed by documentary proof, to PMO, Ministry of Civil Aviation, Directorate General of Civil Aviation, and Aircraft Accident Investigation Bureau, requesting the hypothesis be formally tested by IIT Bombay, Aeronautical Development Agency, or Hindustan Aeronautics Limited before any conclusion is reached on the cause of the accident.
The submission draws entirely on Boeing’s own technical manuals, a relay manufacturer’s datasheet, and safety investigation reports filed by American and Japanese aviation authorities following a 2013 Boeing 787 battery fire.
“Media reports continue to suggest pilot action (suicide theory). However, International Civil Aviation Organisation Annex 13 requires all credible technical causes be ruled out first. This technical note suggests a credible cause,” said the FIP letter. It stressed the sequence of events it has laid out be treated as a “testable hypothesis”.
The sequence the FIP proposes begins with a lithium-ion battery failing internally during the take-off roll. This type of failure was documented in the 2013 Japan Airlines battery incidents at Boston and Takamatsu. Such a failure discharges enormous current through the aircraft’s metal structure. “The surge raises the voltage of what should be a stable zero-volt ground reference, creating electrical disturbances that the system reads as a loss of power,” said a senior commander explaining the FIP letter.
The aircraft’s ‘Battery Power Control Unit’ responds automatically, deploying the Ram Air Turbine (RAT), which is an emergency power-supplying windmill. “That deployment is the most critical part of the argument as RAT deployment places the aircraft in ‘Standby Operating Mode’. This then closes two contactors that connect the commander’s and co-pilot’s left and right instrument buses through a shared return path. It is through this newly bridged circuit that the voltage disturbance reaches the fuel control relays of both engines,” he said.
Those relays are electrical switches that stay in whatever position they are last set to, until something moves them. The letter identifies the exact make and model used in Boeing 787, and the manufacturer’s instruction sheet warns that if voltage runs through the switch in the wrong direction, the switch can flip. A battery fault creates that wrong-direction voltage which can flip switches from ‘RUN’ to ‘CUT OFF’ . The valves feeding fuel to the engines slam shut, and both engines starve simultaneously.
