British Airways A319 near Palma Mallorca on Apr 2nd 2019, flight control problems
Last Update: January 10, 2020 / 20:56:28 GMT/Zulu time
The UK AAIB reported the occurrence was rated a serious incident and is being investigated.
The aircraft remained on the ground in Palma Mallorca for about 15 hours, then positioned back to London Gatwick as flight BA-9254 and returned to service.
On Jan 9th 2020 the AAIB released their bulletin concluding the probable causes of the incident were:
Following maintenance action intended to deactivate a spoiler, the aircraft departed with the spoiler in the maintenance position. This allowed the spoiler to ‘float’ up in the airflow causing an uncommanded roll input. The aircraft landed without further incident and the spoiler was correctly deactivated for the return flight.
The operator’s safety investigation identified that the LAEs had not followed the AMM procedure correctly. The maintenance activity was, by necessity, being conducted in bad weather and it was an unfamiliar task. They were distracted during the task and had difficulty using the APP on the tablet device which was provided to display the required maintenance information.
The LAEs had difficulty interpreting the modification status of the actuator and identifying the relevant sections of the procedure to use, relating to the modification status and position of the actuator, on the tablet device they were using. They were not clear on how the maintenance key was to be used to deactivate the spoiler actuator for dispatch. A physical check for correct deactivation was not completed and an independent check for correct deactivation was not required to be carried out. The log book entry for the deactivation was incorrectly certified.
The operator’s report also identified a number of contributory factors including how the maintenance information was accessed and presented to the engineers, and differences in how similar information is presented more effectively to flight crews.
The AAIB reported following a flight control message prior to departure maintenance intended to de-activate the #1 spoiler on the left hand wing. The AAIB described the sequence of events in flight:
The departure was normal but whilst in the cruise, the crew noticed that the aircraft was flying 2⁰ left wing down with 2.4 units of right rudder trim; a light “rumble” was apparent.
As the flight progressed, the crew monitored the situation and consulted with the operator’s maintenance control. The senior cabin crew member was asked to visually check the wing and its control surfaces for anything unusual. In the absence of any warnings or confirmed abnormalities, the crew decided to continue the flight to the planned destination.
During the approach with the autopilot engaged, when full flap was selected the aircraft rolled noticeably to the left and deviated from the flight director command bars. This was accompanied by buffeting and vibration which felt like “light turbulence”. The crew observed the operating spoilers on the right wing were repeatedly extending and retracting and that the autopilot had applied 6.6 units of right rudder trim as it regained the approach profile.
The crew reviewed the situation and decided to continue the approach. At 1,000 ft agl, the stable approach criteria were met and at 800 ft agl the handling pilot disconnected the autopilot. This introduced a further roll to the left which was contained by the pilot. The aircraft was out of trim and required continual sidestick input, sometimes to nearly full extent, to maintain the approach profile. The crew reviewed the situation again and decided to land. The landing and taxi to stand were without incident.
On arrival, maintenance staff inspected the aircraft and found that instead of the No 1 spoiler being deactivated it had been left in the maintenance position with the maintenance key still installed. The ‘remove before flight’ flag attached to the maintenance key had been cable tied to the spoiler actuator, Figure 1. In this configuration the spoiler could move away from its stowed position in an uncontrolled manner which would cause the anomalies experienced by the crew.
The spoiler was then correctly deactivated, and the aircraft returned to Gatwick Airport without further incident.
The AAIB described the maintenance actions:
The aircraft had returned to stand due to a flight control (flt ctl) status massage which had been displayed to the flight crew whilst taxiing. Two licensed aircraft engineers (LAEs) were sent to meet the aircraft and investigate the cause of this message. They had just commenced their shift. On arrival at the aircraft, they debriefed the flight crew and began their fault finding. During this process, they had to go outside of the aircraft to restore ground power after it had failed.
Both LAEs had been issued with tablet devices containing approved aircraft maintenance data which was accessed via an APP. After some confusion surrounding the fault codes and difficulty with the Trouble Shooting manual (TSM), it was confirmed that the No 1 spoiler actuator was not operating correctly.
The LAEs then referred to the paper copy of the Minimum Equipment List (MEL), kept in the flight deck, to see if the aircraft could be dispatched with this defect. Dispatch of the aircraft was allowable with the No 1 spoiler deactivated providing the appropriate procedure in the Aircraft Maintenance Manual (AMM) had been completed. This procedure required the use of a special tool, a spoiler maintenance key, which had to be collected from the engineering stores. Both LAEs returned to the engineering offices to collect the tool and their wet weather clothing due to the worsening weather conditions.
On returning to the aircraft the LAEs completed the deactivation procedure. It was now cold and raining. An operational test was carried out and indications from the ground and on the flight deck displays were as expected. A check to see if the spoiler could be manually raised was not carried out.
The LAE who had completed the deactivation was unable to complete the technical log as his hands were too cold and he “could not feel his fingers”, so the other LAE completed the certification; which was outside the scope of his approval. The aircraft then departed.
When the LAEs later learnt of the flight crew reports of a control anomaly, they realised that the spoiler had been incorrectly locked out and they reviewed the deactivation procedure on a desk top computer.
This article is published under license from Avherald.com. © of text by Avherald.com.
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