Beech C90 N20 accident near Fort Worth, Texas

Probable cause

The failure of the nose gear actuator due to insufficient lubrication of the nut assembly threads.

NTSB analysis

As the landing gear was extended, the flightcrew heard a loud "bang" and observed a “Gear Unsafe” indication. After making a low pass, tower personnel reported that the main gear appeared to be down but that the nose gear was only partially extended. The certificated flight instructor raised the landing gear and made another low pass. Tower personnel said the main gear was up, but the nose gear was still only partially extended. The flightcrew elected to return to their home base and land. As speed dissipated, the nose gear folded and the airplane slid to a stop. A postaccident examination revealed that the nose gear actuator had failed due to insufficient lubrication of the nut assembly threads. The manufacturer recommends that the actuator be overhauled or replaced every 8000 cycles, or 6 years, whichever occurs first. At this time, the screw and nut assembly is to be greased. The failed actuator had accrued 1,576 cycles and 951.2 hours time-in-service. The maintenance manual does not require in-service lubrication of landing gear actuator.

Text from the NTSB. Open the NTSB docket for CEN10LA302 for the full record.