A Beechcraft Super King Air B200C was operating a charter flight on this day in (recent) aviation history in 2023. On board the aircraft a crew of two (the Pilot in Command as Pilot Monitoring - PM and a Co-Pilot as Pilot Flying - PF) and five passengers. The flight had originated at Tari Airport, Hela Province and had Jacksons International Airport, National Capital District, Papua New Guinea as its destination.
The aircraft in its final position shortly after landing (Source: thenational.com © Unknown
While on the approach to Jacksons, approximately 7 NM from the runway, passing 2200 feet (AMSL), the crew observed that the Unsafe Gear Indication was on after selecting the landing gear down. Both the main landing gears indicated down and locked, but the indication for the nose landing gear showed two red, parallel-wired lights. Indicating that the NLG was not down and locked. The landing gear was cycled, but the unsafe indication for the nose landing gear remained. A missed approach was flow, continuing on the runway heading, climbing to 2500 feet ASML. During the climb, while at 1700 ft ASML the Landing Gear Alternate Extension-Manual (Mechanical Landing Gear System) Procedure, the red light remained illuminated for the NLG. Subsequently, two low passes were flown, one so ATC could verify the gear position and a second to allow maintenance staff to confirm the gear position. Both advised the crew that the nose landing gear was not fully extended. With all possible actions taken the only option left was a landing with the gear partially extended. The aircraft landed on runway 14 at Jackson, ~520 meters after touchdown the nose landing gear collapsed. the aircraft continued for another 105 meters before coming to a stop. There were no injuries to the occupants. Damage to the aircraft was substantial, damage was done to;
Both propeller assemblies
Nose structure of the aircraft
Both nose landing gear doors
Overview of the damage sustained (Source & © AIC)
An investigation was launched by the Papua New Guinea Accident Investigation Commission (AIC), they determined that the NLG collapse during landing roll occurred because the NLG did not fully extend and lock into the fully extended position. The investigation found that this was due to the internal failure of the NLG Actuator.
Further inspections of the faulty NLG Actuator by the manufacturer found that the actuator nut assembly threads were excessively worn, allowing the nut assembly to freely move through the screwhousing without any thread engagement.
The grease in the nut assembly was found to be thick and dry.
The operator had carried out the NLG Actuator lubrication at specified due intervals required by the manufacturer, however, the dry and thick grease identified in the nut assembly indicates that there may have been inadequate grease or lubricant in the nut assembly which depleted over time, resulting in the nut assembly threads excessively wearing out before the next service (inspection and lubrication) of the NLG Actuator was due.
The NLG Actuator lubrication carried out by the operator at specified due intervals was incorrectly referenced. The NLG Actuator lubrication procedure, if correctly referenced, would have directed the maintenance personnel to a separate NLG Actuator inspection procedure which is required to be performed to determine whether the actuator should be returned to service and inspected at specified intervals, overhauled or replaced before partially disassembling the actuator for lubrication. The investigation found that there were no records of this coinciding NLG Actuator inspection procedure.
Dried out grease in the nose landing gear actuator (Source and © AIC)
The AIC report, which served as a source for this blog, contains very detailed information with regards to the investigation. It can be accessed by clicking on the .pdf file below;
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