Accident Overview
On June 3, 2010, at approximately 1430 central daylight time, a Beech C90 (registration N20), owned and operated by the Federal Aviation Administration (FAA), was substantially damaged when the nose landing gear collapsed during landing at Alliance Fort Worth Airport (AFW) in Fort Worth, Texas. The training flight, conducted under 14 CFR Part 91 without a flight plan, originated from AFW at 1305. Visual meteorological conditions prevailed. The two pilots on board were not injured.
Sequence of Events
The purpose of the flight was to maintain inspector currency. After completing air work, the airplane proceeded to Waco Regional Airport (ACT) in Texas for takeoffs and landings. During the first approach, as the landing gear was extended, the crew heard a loud bang and received a "GEAR UNSAFE" indication. A low pass was performed, and ACT tower personnel reported that the main gear appeared down, but the nose gear was only partially extended. The instructor then raised the landing gear and conducted another low pass, at which time tower reported that the main gear was up, while the nose gear remained partially extended. The crew returned to AFW and, after consulting with the Flight Standards District Office (FSDO), Oklahoma City maintenance, and Hawker Beechcraft, decided to land on runway 34L. As speed dissipated, the nose gear folded, and the airplane slid to a stop, damaging the nose wheel bulkhead.
Post-Accident Examination
Examination of the aircraft after the accident revealed that the nose gear actuator (part number 50-820208-5, serial number 93963) had failed. The actuator was sent to Aerospace Turbine Rotables, Inc. in Wichita, Kansas, for disassembly and inspection. According to their Teardown and Inspection Report, "The most probable root cause of the actuator failure was relevant to insufficient lubrication of the nut assembly threads."
Maintenance Findings
The FAA reported that the Hawker Beechcraft maintenance manual for the Beech C90 did not require in-service lubrication of the landing gear actuator. The mechanical actuator was to be overhauled or replaced every 8,000 cycles or six years, whichever came first, during which the screw and nut assembly was to be greased. The FAA noted that the actuator on N20 had accrued 1,576 cycles and 951.2 hours time-in-service before failure. Hawker Beechcraft confirmed that there was no lubrication requirement at the time of the accident. Consequently, the company stated that it had implemented a change to the King Air maintenance manual to include a lubrication requirement for the screw and nut assembly.