The crash of AI 171 has sparked competing theories, with no consensus yet on the cause. Central to the investigation is whether the Boeing 787’s advanced electrical systems failed. The aircraft’s shift from traditional pneumatic and hydraulic systems to a “more-electric” design aimed to reduce weight and costs, but pilots and experts now suspect this could have played a critical role in the tragedy.
A national daily has reported that the lone survivor heard a loud boom, likely signalling a single engine failure. However, a single engine failure should not cause a modern aircraft to crash. So what went wrong next? Did the second engine fail? Or was there a total electrical failure?
Dual engine failures are extraordinarily rare—only seven documented cases worldwide in seven decades—typically caused by bird strikes, fuel contamination, or pilot error. In the case of AI 171, bird strike has been largely ruled out. The infamous incidents referenced include the 2009 US Airways Hudson River landing (bird strike), 1989 British Midland Flight 92 (wrong engine shutdown), and other technical or fuel issues.
A senior Boeing 787 commander confirmed to the daily that the boom likely indicated one engine’s partial or complete shutdown but questioned what happened thereafter. Did pilots mistakenly shut down the functioning engine, as happened in past crashes? Many pilots say shutting off fuel to a faulty engine takes time and only begins at about 400 feet altitude—too late in this case, since the crash occurred earlier.
Other possible pilot errors have been suggested. Could the “startle effect”—an involuntary reaction to a sudden emergency—have caused the crew to forget to retract the landing gear? Or did they retract the flaps by mistake instead? The same commander argued that even if these errors occurred, with one engine still operational, the aircraft should have been able to climb and return safely.
It is the rare “both engines down” scenario that has pushed some to focus on electrical failure. A senior Airbus commander explained that preliminary assessments suggest one or more Variable Frequency Starter Generators (VFSGs)—which start engines and provide main electrical power—may have failed or been electrically isolated during takeoff. This could have caused a partial or total loss of engine control.
Another senior pilot elaborated that VFSG failure could disable the Electronic Engine Controls (EEC), the “throttle computers” dependent on electrical power. If both engines and the Auxiliary Power Unit (APU)—a backup power source—fail or disconnect simultaneously, the EECs might cease controlling thrust, leaving engines stuck at idle and pilots powerless to increase thrust.
However, the simultaneous failure of both engines and APU is exceptionally rare. Pilots noted that APUs take over 90 seconds to spool up to engine RPM and support flight, while this accident unfolded within 32 seconds—too brief for APU intervention.
Following DGCA safety directives issued the day after the accident, some senior pilots believe early findings point to an electrical system malfunction compromising engine responsiveness. Supporting this theory is evidence of the Ram Air Turbine (RAT) deployment—a small wind turbine that extends from the aircraft’s belly to power critical flight controls in emergencies.
Pilots have observed a small, hazy black patch beneath the wreckage, speculating it may be the RAT. Unlike the APU, RAT cannot provide sufficient power to safely land the aircraft, underscoring the severity of power loss.
Meanwhile, an air safety expert proposed a more straightforward explanation: cargo overloading. He suggested the plane’s unusually long runway takeoff and failure to maintain altitude after one engine failure could be explained by excess weight.
A senior Boeing 777 pilot also raised the possibility that pilots entered incorrect zero fuel weight data, neglecting the 50-60 tons of fuel aboard at takeoff. This would reduce thrust settings, and combined with an engine failure, could cause a critical thrust loss. However, this was disputed by a Boeing 787 commander who stated the aircraft’s systems, monitoring wheel weight, would have alerted pilots to such discrepancies.
Also Read: Dreamliner Crash: Veteran Pilot Says Missed Gear Retraction May Be Crucial Clue https://www.vibesofindia.com/dreamliner-crash-veteran-pilot-says-missed-gear-retraction-may-be-crucial-clue/
