Airbus has asked Air In- dia to carry out multiple tests and share the aircraft’s recent maintenance activi- ties as it continues its event assessmentNEW DELHI: “The elevators (control up and down movement of aircraft) and ailerons (controls left and right movement) surfaces were lost for around four seconds.” Airbus, in its initial assessment of the A320 flying from Phuket to Delhi on Aug 4, said the aircraft experienced a sudden loss in altitude that left 24 injured.“Based on analysis of the DFDR (digital flight data recorder),” Airbus found that within seven seconds between 9:32:44 am and 9:32:51 am, there was a loss of hydraulics systems — pressurised fluids which enable flight controls to move. At this point, the autopilot was disconnected and the aircraft’s nose went up (increase in pitch). All timings are in IST.The Airbus preliminary communication sent to AI on Aug 10 says “at (9:32:46 am) auto pilot 2 was disconnected, and full nose down (pitch down) input began being applied on first officer side with no direct response from the flight control surfaces” due to the loss of hydraulics. Five seconds later, a single hydraulic system was recovered and a few seconds later the remaining two systems were back, leading to recovery of normal flight control.Airbus has asked Air India to carry out multiple tests and share the aircraft’s recent maintenance activities as it continues its event assessment. “Since load exceedances were detected during the sudden altitude change, (maintenance) inspections must be performed. Please provide the inspection results once they are completed. Please provide more detailed pilot reports from the reported event clarifying what it is observed during the event,” the communication says.“...this event requires an analysis considering both aircraft systems and structural integrity, as airframe may have been affected by the movement,” it adds.While probe is on by Airbus and France’s accident investigator under the ambit of India’s Aircraft Accident Investigation Bureau, several pilots are questioning why Air India decided to fly the aircraft all the way to Delhi after it had recovered from the technical events.