Incident Overview
During a flight, the pilot attempted to extend the landing gear but was unable to do so using either the normal or the emergency hydraulic pump. As a result, a wheels-up landing was performed.
Investigation Findings
Following the incident, an examination of the hydraulic powerpack, part number 1280510-1, was conducted. The investigation revealed that the secondary pressure relief poppet valve (MS134345) was off its seat and jammed between the spring button and the powerpack body. This condition prevented the hydraulic system from being pressurized, rendering the landing gear extension system inoperative.
Technical Details
The hydraulic powerpack and the affected poppet valve had accumulated 1,792 hours of operation prior to the failure. The jamming of the poppet valve was identified as the direct cause of the system's inability to pressurize, leading to the gear extension failure.