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ASN Wikibase Occurrence # 143735
Last updated: 22 October 2017
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Type:Silhouette image of generic SW4 model; specific model in this crash may look slightly different
Swearingen SA227-AT Merlin IVC
Owner/operator:Toll Aviation
Registration: VH-UZA
C/n / msn: AT-502
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Airplane damage: Substantial
Location:Brisbane International Airport, QLD (BNE/YBBN) -   Australia
Phase: Landing
Departure airport:Brisbane International Airport, QLD (BNE/YBBN)
Destination airport:Brisbane International Airport, QLD (BNE/YBBN)
At 01:27 local time, an SA227-AT Merlin IVC aircraft, registered VH-UZA, departed from Brisbane Airport for a test flight following maintenance. There were two pilots and no passengers on board.

While returning to the airport, the crew advised air traffic control that they had a landing gear problem. The crew conducted two fly-overs of the airport to allow maintenance engineers to observe the aircraft, and the engineers confirmed that the landing gear was still retracted. The crew decided to land the aircraft with the landing gear retracted, and a full emergency was declared. The aircraft belly landed at 02:32. Both pilots escaped unhurt.

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.

Contributing factors
• The proximity of the landing gear selector valve electrical wiring loom to the external hydraulic power connectors within the left engine nacelle on Fairchild SA227-AT Metro aircraft resulted in the ‘down selection’ wire being damaged during routine maintenance activities [Safety issue].
• The separation of the ‘down selection’ wire interrupted the supply of electrical power to the down solenoid, preventing extension of the landing gear in the normal operating mode.
• The maintenance practices by a number of personnel prior to the occurrence resulted in missed opportunities to identify an out of rig cable within the landing gear emergency extension system.
• The landing gear did not extend in the emergency extension mode in-flight due to the out of rig cable preventing correct actuation of the by-pass and shut-off valves.
• The flight crew were unable to extend the landing gear using the normal and emergency extension procedures, resulting in the need for a gear-up landing.
Other factors that increased risk
• The manufacturer’s operational and maintenance documentation suite contained inconsistencies in some procedures.
Other findings
• The crew conducted the emergency procedures to extend the landing gear in a manner that should have allowed the landing gear to extend.
• The low-level fly-past provided for independent confirmation that the landing gear was fully retracted and the gear doors closed.



Photo: ATSB

Revision history:

15-Feb-2012 03:36 harro Added
15-Feb-2012 03:40 harro Updated [Narrative]
15-Feb-2012 04:01 RobertMB Updated [Aircraft type, Narrative]
16-Feb-2012 09:49 harro Updated [Aircraft type, Narrative]
31-Aug-2014 19:50 Aerossurance Updated [Narrative]
29-Sep-2014 17:52 Aerossurance Updated [Narrative]

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