What happened
On 7 December 2014, a Beech 99, registration VQ-THL, was conducting a commercial passenger flight from Providenciales to Grand Turk. During the final approach, the crew received an unsafe indication for the nose landing gear. Attempts to recycle the gear were unsuccessful, prompting the crew to request permission to overfly the airfield so tower personnel could visually confirm the gear's position.
After observing that the nose gear remained retracted, the commander decided to return to Providability, as the airport offered better emergency facilities and served as the operator's maintenance base. While in a holding pattern, the crew attempted to manually extend the gear using the emergency checklist; however, while the main gear extended, the nose leg remained stuck in the up position. Following consultation with the operator's maintenance team, the commander attempted a touch-and-go maneuver to use vibration to shake the gear into place, but this failed to resolve the issue.
The commander declared an emergency and briefed the passengers before landing on the main wheels. As the aircraft slowed, the nose descended to the runway, causing the nose cone and gear doors to scrape the surface. The propeller tips also struck the runway. There were no injuries to the two crew members or two passengers, though the aircraft sustained damage to the nose cone and both propellers.
The investigation
Investigators examined the landing gear mechanism, which utilizes an electric motor and gearbox to drive a linkage. The investigation by the operator's maintenance organization determined that a chain within the nose gear linkage had failed. Specifically, the failure of the master link caused the forward segment of the chain to break, which effectively disconnected the nose gear from the operating mechanism. Because of this specific failure, using the emergency handle only operated the main landing gear.
The chain had been newly installed on 2 October 2014, having flown for approximately 185 hours and completed 540 cycles at the time of the accident. Although the maintenance schedule required inspections every 100 hours, the last inspection had occurred 39 hours and 102 cycles prior to the event.
Findings
- The primary cause of the gear failure was the breakage of the chain at the master link.
- The failure of the master link resulted in the nose gear being isolated from the extension mechanism.
- All fracture surfaces on the components showed evidence of overload.
- While incorrect installation of the master link was theoretically possible, engineers involved in the installation and independent reviewers found no evidence of error.
Safety action
- The operator's maintenance organization has updated its maintenance program. Following any maintenance task that requires the removal of this specific chain, an inspection will now be performed after 50 cycles, before reverting to the standard 100-hour interval.