Cessna 560XL N101PG accident near Eugene, Oregon

Probable cause

An uncommanded landing gear retraction after touchdown for reasons that could not be determined because postaccident examination did not reveal any mechanical malfunctions or failures that would have precluded normal operation.

NTSB analysis

The pilot-in-command (PIC) reported that, during the visual approach to the airport, he and the second-in-command (SIC) lowered the landing gear and verified that all cockpit indications showed that the landing gear were in the down-and-locked position. The airplane touched down smoothly on the main landing gear (MLG) and then touched down on the nose landing gear (NLG). The PIC had his hand on the thrust reversers when he and the SIC heard the landing gear unsafe horn; the left MLG then collapsed followed immediately by the collapse of the right MLG and the NLG. The airplane slid on its belly for about 1,500 ft before it came to rest on the runway. Cockpit voice recorder data confirmed that the unsafe landing gear configuration warning did not occur before touchdown as reported by the PIC.

Postaccident examination revealed that, although the landing gear handle was in the down-and-locked position, all of the landing gear were fully retracted and engaged in their respective uplocks. Extensive testing of the airplane's hydraulic and electrical systems did not reveal any malfunctions that would have resulted in an uncommanded gear retraction. Some small, fine particulate matter was observed within the hydraulic manifold assembly; however, testing was unable to determine if these particles contributed to the uncommanded landing gear retraction.

Text from the NTSB. Open the NTSB docket for WPR12FA193 for the full record.