An unusual smell was noticed soon after takeoff, the source of which could not be determined. The flight crew donned their oxygen masks and carried out the appropriate actions to deal with the situation, while arranging with ATC for a return to Heathrow.
Subsequent investigation revealed that hydraulic fluid leaking from a hydraulic actuator had been ingested into the air conditioning system. Following appropriate maintenance action, the aircraft was returned to service and no recurrence has been reported.
Airbus A320-232 G-TTOB 03-15