What happened
On 11 May 2011, a Piper PA31-350 Navajo Chieftain was conducting a training flight at Nelson Aerodrome when its nose landing gear malfunctioned. During the flight, the nose gear became stuck in a partially retracted state and could not be extended. The crew, consisting of two pilots, was forced to perform a landing with the gear in this compromised position. The impact resulted in substantial damage to the aircraft, though there were no injuries to the occupants.
The investigation
Investigators examined the mechanical state of the landing gear and the aircraft's maintenance history. The inquiry established that the nose gear's failure was not an isolated incident; the aircraft had a documented history of similar nose landing gear defects, including previous instances where the gear failed to extend or retract properly.
Further scrutiny of the maintenance records revealed that several previous repairs and rectifications performed by various organizations had been non-compliant with Civil Aviation Rules. These issues stemmed from the use of incorrect parts and unauthorized repair methods that deviated from the manufacturer's official Maintenance Manual procedures.
Findings
The investigation determined that the primary cause of the jam was the use of incorrect parts and improper maintenance practices accumulated over several years. Specifically, the misalignment of two critical components allowed the nose landing gear to rotate excessively when full rudder was applied during the training maneuver. This increased angle prevented the gear from centering correctly during the retraction cycle, leading to the mechanical jam.
Safety action
Following the investigation, the Commission identified significant concerns regarding the standard of maintenance for general aviation aircraft in New Zealand. To address these risks, recommendations were made to the Director of Civil Aviation to improve compliance within the general aviation maintenance sector. Additionally, the Commission suggested expanding the requirement for duplicate inspections, particularly for aircraft involved in air transport operations, to mitigate the risk of recurring mechanical defects.