Air India's Airbus A320 flying from Phuket to Delhi on August 4 lost flight controls for four seconds after multiple hydraulic systems failures, causing the aircraft to suddenly lose 300 feet in altitude, according to an initial Airbus analysis.
The analysis showed that the aircraft suffered three hydraulic system failures within two seconds and the systems were recovered in seven seconds.
At least 24 people out of the 145 people onboard were injured in the incident that is being probed by the Aircraft Accident Investigation Bureau
With the hydraulic system failures, the report said, "elevators and ailerons surfaces were lost for around 4 seconds".
Elevators and ailerons are key flight controls. While elevators control up and down movements, ailerons control left and right movements.
This means the flight controls were lost during Air India's Phuket-Delhi flight AI2379 for four seconds on August 4 before the systems recovered.
Just before 9:32:44 IST (4:02:44 UTC), there was loss of one hydraulic system, and at 9:32:45 IST (4:02:45 UTC), the two other hydraulic systems were also lost, as per the report.
Then at 9:32:51, all three systems were recovered.
The report said the system behaviour was due to the loss of hydraulic pressure as at least two pressure switches showed low hydraulic status that led to the loss of actuators.
During the short period of multiple hydraulic system failures, the first officer tried the input for full nose down or pitch down of the aircraft, but the flight controls did not respond, the report said.
Airbus noted that since the post flight report indicates multiple faults, the analysis focused on various aircraft systems as the sudden loss of altitude.
In the analysis report, dated August 10, which is six days after the incident, Airbus has sought more details from Air India.
Details about the subsequent updates related to the incident could not be ascertained.
AAIB, on August 11, said the A320 aircraft with registration VT-EXO operating AI 2379 experienced a sudden altitude variation of approximately 300 feet during cruise.
The aircraft subsequently stabilised and landed safely at Delhi.
The probe agency had also said that it was engaged in the systematic collection, preservation and examination of all relevant technical, operational, medical and human-factor evidences.
"This includes examination of the aircraft and its systems, recorded flight data, relevant operational and maintenance records, medical information, and interviews with persons concerned. All material evidence will be examined in its entirety before any conclusions are drawn," it had said.
Meanwhile, the pilot-in-command of the flight has tested positive for a psychoactive substance, following which Air India has decided to carry out testing of all pilots for such substances.
The test will cover over 5,000 pilots of Air India and Air India Express, both owned by the Tata Group.
(With inputs from PTI)
