Cessna 210 N3607Y accident near Juneau, Alaska

Probable cause

A loss of hydraulic fluid due to a fractured left main landing gear hydraulic actuator as a result of a fatigue crack, which led to the landing gear collapsing upon touchdown.

NTSB analysis

The private pilot was conducting a personal cross-country flight. In preparation for landing at the destination airport, the pilot selected the landing gear handle to the "down" position. The nose gear fully extended and locked into place, but the left and right main landing gear extended only about halfway and then stopped. The pilot's efforts to cycle the landing gear were unsuccessful, and he subsequently conducted an emergency landing to an alternate airport, during which the landing gear collapsed upon touchdown with the runway.

After the accident, the airplane was lifted with a crane and positioned in a level attitude, and hydraulic fluid was observed leaking from the bottom of the airplane. A postaccident examination of the hydraulic system revealed that the left main landing gear hydraulic actuator was fractured due to a fatigue crack that had initiated at the retaining ring recess in the housing and propagated through most of the barrel housing cross-section. Once the actuator was substantially weakened, the housing cracked further from overstress.

Text from the NTSB. Open the NTSB docket for ANC15LA048 for the full record.