Incident Details
On 2 March 2016, after pushback from the parking stand to begin flight LO79, the crew of a Boeing 787-800 found that the elevator controls were locked and the control column was jammed. The aircraft returned to the parking stand. A maintenance team from MAEL entered the aircraft to assess the defect and performed a check, which was recorded in the LDP-60 log. At the same time, a mechanic from LOT AMS approached the aircraft, entered the forward electronic equipment bays, and removed the rig pins locking the control column without notifying the MAEL team. The mechanic then boarded the aircraft and informed the MAEL team that everything was in order, but refused to make an entry in the LDP-60 documentation.
Investigation
The investigation revealed that the aircraft had undergone maintenance by LOT AMS from 29 February to 2 March 2016 (Work Package No 109713). One of the tasks performed on 29 February between 13:00 and 15:00 LMT on the apron in front of the hangar was a check of elevator deflections (per TC 27-250-00-01/02), which requires installation of rig pins E1 and E2. The rig pins were part of a Boeing kit (P/N K20009-1) owned by PLL LOT and stored at LOT AMS. According to information sent by LOT AMS to PLL LOT, the cause of the elevator lock was a left-in-place lockout device used during maintenance. During LOT AMS's internal investigation, it was found that the rig pins E1 and E2 were loosely packed in the Boeing kit, making it difficult to check that the kit was complete.
Probable Cause
The probable cause of the incident was leaving the elevator control system (control column) lock installed after maintenance, which was not detected due to a lack of appropriate quality control of the work performed, caused by human error in failing to follow the procedure in DMC-B787-A-27-31-09-01B-340A-A and the LOT AMS procedure in MH regarding the use of tools during maintenance.
Preventive Actions
PLL LOT registered the event in their SMS database and classified it according to their criteria. Preventive actions taken by LOT AMS included:
- Retraining of four mechanics involved on Human Factors, completed successfully.
- Reduction of privileges for level C and B1 personnel involved.
- Issuing an order to perform functional tests of control systems after hangar maintenance before releasing the aircraft.
- Requiring personnel issuing CRS to verify the completeness of tools and GSE via the AMOS system.
- Transferring all non-LOT AMS tools and GSE for Boeing 787 to a central tool store.
- Marking all GSE with red "Remove Before Flight" flags.
- Reorganizing the rig pin set in containers with holders for easy completeness check.
- Issuing a safety bulletin and requiring all maintenance personnel to review it.
- Updating maintenance procedures in the Technical Maintenance Manual.
- Distributing incident materials for use in Human Factors and type training.
- Requiring supervisory personnel to emphasize adherence to MOE and MH procedures.
No safety recommendations were issued by the commission.