Wheels up landing involving a Cessna Aircraft Company 210K, VH-NLB, Archerfield, QLD on 25 April 1993

On selecting gear down, there was no green light indication in the cockpit and the landing gear motor continued to operate. The pilot noticed that both maingears were trailing. He was unable to retract or extend the landing gear by either the normal or emergency extension systems. The aircraft was landed in this configuration. Investigation found that the retaining circlip in the hydraulic ram for the left main landing gear door had failed. This allowed the actuating ram to separate from it's housing and seal, causing the the loss of all hydraulic oil from the landing gear reservoir. The cause for the circlip failure could not be determined.