Cessna T210L N2425S accident near Marana, Arizona

Probable cause

A failure of a retaining ring in the airplane’s left main landing gear door actuator and the subsequent complete loss of hydraulic fluid, which resulted in a gear-up landing.

NTSB analysis

During a post-maintenance test flight after an engine overhaul and annual airframe inspection, the pilot retracted the landing gear as he departed the runway. While on the downwind leg of the airport traffic pattern the pilot lowered the landing gear handle, but the landing gear remained retracted and stowed and the associated green indicator light was not illuminated. The pilot attempted to troubleshoot the anomaly and eventually performed an emergency landing. The airplane touched down on the partially extended nose landing gear and fuselage, resulting in damage to the left horizontal stabilizer and elevator.

Postaccident examination of the landing gear system revealed that the left main landing gear actuator retaining ring separated from the actuator cylinder, exposing the internal rod and O-rings. The separation exposed a hole in the cylinder and a loss of hydraulic fluid followed, leaving the system unpressurized. The lack of system pressure resulted in the failure of the nose landing gear door actuator assembly and the subsequent gear-up landing. The retaining ring inside the actuator cannot be visibly inspected due to the position of the seat being recessed into the cylinder. The actuator does not have a specified overhaul time or cycle limit.

Text from the NTSB. Open the NTSB docket for WPR23LA012 for the full record.