Cessna 172RG N9985B accident near Lexington, Kentucky

Probable cause

The rupture of the landing gear’s hydraulic pressure hose, which resulted in the depletion of all of the hydraulic fluid, and the inability of the landing gear to raise or lower. Contributing to the accident was the installation of an unapproved hydraulic hose by unknown maintenance personnel.

NTSB analysis

Upon arrival at the intended destination airport during an instructional flight, the pilot receiving instruction attempted to extend the airplane's landing gear. Only the nose gear and the left main landing gear extended and locked in the down position. Both pilots reported they attempted to retract the landing gear; however, the left main landing gear remained in the down and locked position and the nose landing gear's position could not be determined. The flight instructor reported that he performed the emergency gear extension procedure specified in the airplane's flight manual, but the right main landing gear did not extend or lock into position. The pilots elected to divert to a nearby airport. During the landing roll, the airplane veered off the runway, resulting in substantial damage to the elevator. An examination of the airplane revealed that a landing gear pressure hose had ruptured and the hydraulic fluid was depleted. It was constructed of material similar to that used in the automotive industry, thus, the hose likely was not an approved airplane part. No logbook entry was provided that disclosed when the hose was replaced or inspected. Because of the rupture, the lack of hydraulic fluid within the system precluded the right main landing gear from extending and locking as well as the left main and nose landing gear from retracting.

Text from the NTSB. Open the NTSB docket for ERA13LA058 for the full record.