Accident Overview
A pilot conducting a night instrument approach in instrument meteorological conditions (IMC) experienced a failure of the main landing gear to extend properly. The incident occurred when the pilot selected the gear handle down; while the nose gear extended and indicated down, neither main landing gear indicated a down-and-locked position.
Sequence of Events
After recycling the landing gear multiple times without achieving a down indication for the main gear, the pilot activated the emergency blow-down gear extension system. This system extended the nose gear and left main gear, but the right main gear did not indicate down. Because the gear could not be retracted once the blow-down system was used, and with severe weather present, the pilot decided to continue the approach and land with the right main gear not fully extended.
During the landing roll, as the aircraft slowed, the right wing contacted the runway, causing the aircraft to slide sideways. The nose gear and left main gear collapsed during the slide, and the right main gear, which had partially emerged from its wheel well, was torn from the wing.
Investigation Findings
Postaccident inspection of the landing gear extension and retraction system revealed that the hydraulic fluid in the right main gear actuator contained 30% water by volume. The surface temperature near the time of the landing was 23 degrees Fahrenheit. The aircraft had been at altitude for over an hour before beginning the approach. Investigators found evidence that during the flight, water in the actuator had frozen, and the resulting ice had prevented the actuator from functioning properly when the pilot attempted to extend the gear. The source of contamination—how or when the hydraulic system of the 19-year-old aircraft became contaminated—was not determined.