What happened
On 9 February 2011, an Air Nelson Limited Bombardier DHC8-311 (Q300) departed Hamilton Aerodrome for a scheduled service to Wellington Aerodrome. The aircraft was carrying 41 passengers and a crew of three. Before departure from Hamilton, the crew identified a malfunction in the nosewheel steering caused by a faulty cockpit inhibit switch. Because the nosewheel steering is classified as a non-essential system, the aircraft was permitted to depart under the provisions of the approved Minimum Equipment List (MEL).
During the approach to Wellington, the crew attempted to extend the landing gear, but the gear failed to deploy. The pilots initiated a go-around to execute emergency procedures found in the Quick Reference Handbook (QRH). While the alternate gear extension system successfully deployed the main landing gear, the nose landing gear remained stuck in the retracted position. The crew subsequently diverted to Woodbourne Aerodrome, where they performed a landing with the nose gear up. There were no injuries to the passengers or crew, though the aircraft sustained damage to the forward fuselage and the nose gear area.
The investigation
The investigation focused on why the nose landing gear failed to extend despite the use of the alternate system. Investigators determined that the mechanical components of the alternate extension system were functioning correctly. Instead, the failure was attributed to the crew not applying sufficient physical force to the handle required to release the uplock.
Furthermore, the investigation examined the relationship between the initial nosewheel steering failure and the subsequent gear issue. It was found that the MEL allowed for departure with inoperative steering without accounting for the fact that the steering system shared hydraulic power with the landing gear extension system. The investigation also looked into training discrepancies, noting that the force required to operate the handle in the actual aircraft was significantly higher than the force required during simulator training.