What happened
On May 18, 2002, a Voyageur Airways Beechcraft King Air A100, registration C-GISH, departed Oshawa Municipal Airport for an instrument flight rules ferry flight to North Bay, Ontario. The aircraft was carrying two pilots and one non-revenue passenger. Shortly after takeoff, while the crew was attempting to retract the landing gear, a loud grinding noise was heard, and a warning light indicated the nose gear was not fully up. The crew observed that the nose gear remained partially extended.
During the flight, the crew attempted various procedures to secure the gear, including performing positive and negative G manoeuvres to encourage locking. To mitigate the impact of a potential nose-heavy landing, the first officer removed several passenger seats to shift the aircraft's centre of gravity toward the rear. Upon arrival at North Bay, the aircraft landed on Runway 08. As the aircraft made contact with the runway, the partially extended nose gear collapsed. The impact caused substantial damage to the nose gear doors and both four-bladed propellers. There were no injuries to the crew or the passenger.
The investigation
Investigators examined the nose landing gear actuator, which had completed 2013 cycles since its last overhaul. A teardown of the component revealed that the threads of the aluminum-bronze alloy nut had failed due to wear. While the screw and nut were relatively free to move, the internal threads had disintegrated into small pieces. Notably, while grease was present on the walls of the assembly, there was no grease found within the actual threads of the screw and nut.
Technical documentation for the King Air 100 and 200 series was also reviewed. Although the manufacturer had issued communiques stating that internal lubrication (repacking) of these actuators was no longer required, the maintenance manuals for the two models contained slightly different instructions regarding disassembly and lubrication. This discrepancy created a risk of inconsistent maintenance practices.
Findings
- The nose landing gear actuator failed prematurely because of excessive wear of the nut assembly caused by a lack of lubrication.
- The specific reason for the lack of grease—whether due to improper cleaning during inspection, grease migration, or an error during overhaul—could not be determined.
- Inconsistent maintenance practices could potentially occur because the maintenance manuals for the King Air 100 and 200 series contained differing instructions for the end-play check procedure.