A Fairchild Industries Inc2 SA227-AT Metro III took off from Brisbane Airport (Queensland, Australia) on this day in aviation history for a short acceptance flight after a maintenance input in relation to the Fuel Flow Indication system on the left-hand engine.
The aircraft after coming to a stop (Source atsb.gov.uk)
After a short flight, the crew gets cleared for an ILS approach to runway 19 at Brisbane Airport. When on the approach the landing gear handle is placed in the down position., but none of the gears appear to extend as the normal sounds of the gears extending are absent. This is confirmed with the gear indication in the flight deck, none of the gears are down and locked. ATC is informed by the crew and they are vectored to a holding pattern to the east of the airport. While in the holding the crew completed the procedure in chapter 4.5 of the Quick Reference Handbook (QRH), LANDING GEAR FAILS TO EXTEND. Upon completion, the landing gears were still not down and locked. All the gear position indication lights remained off, indicating the gear was still up and locked. Subsequently, the crew performed the QRH procedure from chapter 4.6, LANDING GEAR EMERGENCY EXTENSION.
During the completion of this procedure, the gear indication changed from no indication (Gear up and locked) to three red lights (Gear unlocked and in transit). The next step was the operation of the emergency hand pump to pump the gear down. But already after a few strokes (with ever-increasing resistance), it became impossible to operate the pump. The gear still did not extend and lockdown. In accordance with an additional procedure in the QRH the speed was reduced to just above the stall speed and again attempt the emergency extension mode. Still, the gear failed to extend.
Recovery of the aircraft in progress (Source atsb.gov.uk)
After consulting with the maintenance department the crew performed some maneuvers to increase the G-loading attempting to get the gear moving but the gear indication remained "unlocked and in transit. After several more attempts to lower the gear and two low passes over the airport, the situation had not changed.
This left no other cause of action as to prepare the aircraft in accordance with QRH procedure 4.7 "GEAR UP LANDING". Before the start of the approach the left engine was shut down and just before touchdown (at 200 ft height) also the right engine was shut down. At 02.30 local the aircraft touchdown down on two propellor blades and when the airspeed dropped also the tail contacted the runway. After the aircraft came to a stop the crew evacuated the aircraft. An investigation into the occurrence resulted in several contributing factors, which can be found in the full report that can be read by clicking here. Two main issues identified were;
The down-selection wire to the landing gear selector valve was damaged, preventing the supply of electrical power to the down solenoid, preventing extension of the landing gear in the normal operating mode.
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 aircraft being recovered after the incident. (Source Toll Aviation Pty Ltd)