On 15 February 2012, a Toll Aviation Pty Ltd Fairchild Industries Inc SA227 Metro III aircraft, registered VH-UZA, was being operated on a post-maintenance acceptance flight in the circuit at Brisbane Airport, Queensland with two crew on board. On selection of the landing gear handle to the down position, the landing gear would not extend. After unsuccessful attempts to extend the landing gear in both normal and emergency gear extension modes, the crew decided to conduct a wheels-up landing. At about 0230 Eastern Standard Time the aircraft landed along the centre-line of runway 19. The crew evacuated without injury and the aircraft sustained substantial damage.
What the ATSB found
The ATSB found that an electrical wire to the landing gear selector valve had separated at a connector adjacent to its terminal preventing normal operation of the landing gear to the down position. The investigation also identified an out of rig condition in the landing gear emergency extension system, which prevented correct operation of that system. Factors including the maintenance practices by a number of personnel and inconsistent maintenance documentation contributed to the existence of the defects.
What's been done as a result
The aircraft manufacturer advised that, as a result of this occurrence, re-routing requirements for the landing gear selector valve electrical wiring loom in the Metro aircraft have been distributed to all Metro operators through a Metro Global advisory publication.
The operator carried out a fleet-wide check of the landing gear on its Metro aircraft and rectified any defects found. The operator also re-routed the electrical wiring loom to the landing gear selector valve. In addition, the operator amended the pilot’s quick reference handbook and the Metro phase inspection worksheets and issued an engineering memorandum to all aircraft maintenance personnel detailing the operator’s requirements with regards to following standard procedures and approved data for maintenance tasks.
This investigation highlights the importance of operators and approved maintenance organisations having a detailed understanding of the systems installed on the aircraft types that they are authorised to certify and aircraft manufacturers providing clear and concise maintenance procedures in an aircraft’s suite of manuals.