The Federation of Indian Pilots (FIP) have flagged the preliminary report on Air India flight AI-171 crash and suggested that the deployment of Ram Air Turbine (RAT) may not be linked to the fuel interruption.
In a letter to the Director General, Aircraft Accident Investigation Bureau, the pilots' body said the simulator testing on Boeing 787 does not support the timeline mentioned in the AAIB Preliminary Report, released a month after the crash. Aircraft Accident Investigation Bureau, a body under the the Ministry of Civil Aviation, is investigating the Ahmedabad-London flight crash, that killed 260 people.
The pilots' body have flagged the link between the fuel control switch movement and RAT deployment, suggesting the latter could have resulted from electrical fault or other existing issue. It added that the RAT deployment may have occurred before fuel switch movement.
The FIP said it received a letter from D Michael Andrews, Advocate, representing passengers and families affected by Air India Flight 171.
“While the report indicates RAT power generation approximately 4–5 seconds after fuel interruption, simulator testing reportedly indicates approximately 18 seconds. The letter therefore suggests that RAT deployment may have occurred before fuel control switch movement and may indicate an earlier system or electrical fault requiring further investigation,” the letter read.
What did the pilots' body say?
{{/usCountry}}“While the report indicates RAT power generation approximately 4–5 seconds after fuel interruption, simulator testing reportedly indicates approximately 18 seconds. The letter therefore suggests that RAT deployment may have occurred before fuel control switch movement and may indicate an earlier system or electrical fault requiring further investigation,” the letter read.
What did the pilots' body say?
{{/usCountry}}The letter from the pilots' body flagged several findings of the preliminary report and demanded further investigation. Here are some of the points mentioned in the letter:
- The letter said that RAT deployment may have occurred before fuel control switch movement and may indicate an earlier system or electrical fault requiring further investigation.
- It further said that flight simulator testing indicates that RAT generated power is not produced until around 18 seconds following fuel system interruption. Therefore, the report said the RAT deployment may be unrelated to fuel system changes and instead may be a symptom of faults occurring prior to any fuel disruption.
- Citing the visuals from Ahmedabad airport security camera which showed RAT already deployed on the runway before the aircraft rotates for take-off, the pilots' union said the RAT deployment may have occurred before fuel control switch movement, indicating an earlier system or electrical fault, which required further investigation.
- The report also points out to the episodes leading to the crash, including a loud bang, the dimming of cabin lighting, and ACARS maintenance messages transmitted before the take-off. “Survivor reports referring to a loud bang and dimming of cabin lighting, ACARS maintenance messages transmitted between 0753 and 0808 UTC, and the damage visible in the aft EAFR image reproduced in the Preliminary Report may be examined collectively and correlated with recorded aircraft data to establish a coherent sequence of events and determine whether any electrical system anomalies contributed to the accident,” the letter read.
- It also called for the AAIB to independently verify the acceleration recorded in the preliminary crash report and the relationship between RAT deployment, RAT hydraulic power generation and fuel control switch movement. It added that the findings should be included in the final report.
(With inputs from Neha LM Tripathi)