Cessna Citation 560XL, White Plains, N.Y., April 15, 2008–The Board was unable to determine the cause of the uncommanded landing gear retraction that occurred just after the NetJets-operated Citation Excel touched down at Westchester County Airport. Extensive testing of the airplane’s hydraulic and electrical systems supervised by the NTSB and the FAA failed to reveal any malfunctions that would have caused the gear retraction. Review of the aircraft’s data acquisition system indicated the gear was in the down-and-locked position from approximately five minutes before touchdown until about three seconds after. Post-accident examination of the cockpit showed the landing gear handle in the down position. The Excel sustained damage to its left wing, and a communications antenna was pushed through the pressure vessel. There were no injuries in the incident.
Cessna Citation 550, Salt Lake City, Utah, March 29, 2009–Despite extensive testing, the NTSB was unable to recreate the anomaly or malfunction that caused an uncommanded retraction of the twinjet’s right main gear actuator strut during landing roll-out. The Citation II, operated by Fritzi Jet, was substantially damaged when it departed the runway and struck adjacent lights. Although inspection of the actuator at Cessna revealed three significant anomalies, including a mis-rigging of the actuator downlock switch, worn or overtrimmed back-up rings at the lock piston seals and the lack of required sealant at the downlock switch and the visual indicator, the Board determined that none was a clear cause of the retraction. There were no injuries in the incident.