Airbus probes hydraulic maintenance after Air India A320neo altitude upset

Airbus has asked for details of hydraulic system maintenance carried out on an Air India A320neo after an in-flight upset earlier this month. That request appears in documentation authenticated by a trade publication.

The aircraft was flying from Phuket to Delhi on 4 October when it experienced what India's civil aviation ministry described as a sudden 300ft altitude variation while in cruise. Investigators first suspected turbulence. Since then, inquiries have focused on a temporary loss of all three hydraulic circuits.

The documentation states that the green circuit failed first, with the blue and yellow circuits following almost immediately. That left the aircraft with no aileron, elevator or spoiler control on either side for around four seconds. With the control surfaces in a damping mode, the ailerons moved to a position that produced a nose-up pitch.

The autopilot disengaged during the event. The first officer's side stick recorded a nose-down input, but it had no effect on the control surfaces at the time, since they were disconnected from hydraulic power.

The blue circuit reportedly came back about five seconds after that input, with the yellow and green circuits following shortly after and normal control restored.

Airbus is now looking into the aircraft's hydraulic maintenance history as part of the effort to work out what caused the near-simultaneous loss of all three circuits. No further details on the outcome of that inquiry were available.