Incident Overview
The airplane was on approach to the destination airport when cockpit warnings indicated low hydraulic level and flow. The flight crew attempted normal and emergency landing gear extension procedures, including g-loading maneuvers, but were unable to extend the right main landing gear. The aircraft landed with the right wing main landing gear retracted, causing substantial damage to the right wing and fuselage structures.
Findings
Examination determined that the total loss of hydraulic power to the flaps, spoilers, thrust reversers, and landing gear resulted from a ruptured hydraulic pressure hose assembly. Inspection of the accident hose and exemplar hoses revealed internal wear between the fiberglass within the hose's fire sleeve and the stainless steel braid. The accident hose and two of three exemplar hoses showed no external markings or damage to indicate the internal wear that abraded the stainless steel braiding.
Functional Testing
Functional testing of the landing gear system revealed inconsistent extension sequences during eight actuations. In one actuation, the left main landing gear remained retracted, indicating potential systemic issues.
Manufacturer Actions
Following the accident, the airplane manufacturer was in the process of amending the airplane maintenance manual rigging procedures for the landing gear system and placing service time limits on hydraulic hoses.