Malaysia Airlines has put in place procedures on the use and removal of pitot tube covers for aircraft using Brisbane airport, after an 18 July incident that saw one of its Airbus A330-300s return shortly after taking off with the covers still in-place on three probes.
In its preliminary report on the incident, the Australian Transport Safety Bureau (ATSB) says that the crew operating the A330, registered 9M-MTK, detected airspeed anomalies as the aircraft was on its take-off roll, around 23:31 local time, during a scheduled flight to Kuala Lumpur.
Despite that, there was no indication on the cockpit voice recorders of the crew discussing rejecting the take-off, and after the aircraft took flight, they took actions for unreliable airspeed and made a ‘pan’ call to air traffic control advising that they had unreliable airspeed indicators.
After climbing past 10,000ft, the crew maneuvered the aircraft north of Brisbane to commence troubleshooting and prepare for approach to return to Brisbane airport. In accordance with procedures, the crew turned off the aircraft’s three air data reference systems, and relied on the backup speed scale, which draws data from the angle of attack sensors, and altitude based on GPS data.
The crew had to perform a gravity extension of the landing gear before conducting an overweight landing at 00:33 on runway 1. That caused minor damage to the main landing gear doors from contact with the runway service.
As nosewheel steering was unavailable, the aircraft had to be towed back to the gate where passengers and crew disembarked. No injuries were sustained.
The ATSB says that during its turnaround at Brisbane, duties were being shared between a Malaysia Airlines maintenance engineer who was returning on the departing flight, two non-certifying engineers from a local support provider, and four groundhandling staff.
During the turn, one of the local engineers fitted three pitot covers, “as it was his understanding this was normal practice.” This was communicated to the company engineer, however he later responded that he did not recall hearing this, and no note was made of it in the aircraft’s technical log.
Neither the captain nor the engineer noticed the pitot covers during a walk-around, while the groundhandlers also did not detect it during pushback. The flight crew and company engineer added that the use of pitot covers during aircraft turns was not routine, despite recommendations in the En Route Supplement Australia and Jeppesen’s Australia Airport Directory to use them at Brisbane.
The ATSB says that between 2008 and 2018, there were at least 15 incidents where a pitot tube blockage was detected in aircraft departing Brisbane, with at least four traced back to insect nests causing the blockage.
Following the Malaysia Airlines subsequently provided a notice to all engineers and flight crew to use pitot covers at Brisbane airport during turns or when an aircraft is parked, and procedures to ensure that they are removed prior to flight.
While the ATSB is continuing its investigation, it issued a safety notice to all international operators at Brisbane airport to “to consider the use of pitot probe covers and, if covers are used, ensure there are rigorous procedures for confirming that covers are removed before flight.”