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Challenger 300: Nose Gear Shimmy

January 2014

Over the course of normal operation, it is possible for an operator of a Challenger 300 aircraft to experience a shimmy in the nose gear. But our experience and expertise tell us that operators can sometimes confuse an out of balance nose wheel for a shimmy instead. They are two separate issues and a few more probing questions are necessary to get to the heart of the matter.

Nose Wheel Shimmy

A symptom of a shimmy is the rapid oscillation of the nose wheel moving left to right and causing a shudder that can sometimes be noticed through the rudder pedals. This condition can be isolated by verifying the play at the upper and lower scissors. If play is noted, contact Duncan Aviation’s Accessory Overhaul Services for bushing replacement. If there is no play in the upper and lower scissors, other causes could be steering rack wear, feedback linkage and lower barrel bearing.

Out of Balance Nose Wheel

If the crew is noticing a vertical oscillation vibration through the nose wheel well, sometimes made evident after takeoff, the nose wheel may be out of balance. Remove and balance. Additionally, perform a visual inspection of the nose wheel bearings and ensure the nose wheels are installed using the appropriate maintenance manual torque value.