Shimmy, Shimmy Shake

Editorial Staff

Thursday, March 19, 2020 at 01:45 PM ET

Verified

Key Takeaways:

Shimmy dampener failures are a recurring problem observed across various aircraft types, including Cessna, Pilatus, and Piper models.
These failures manifest as severe nosewheel shimmy, nosewheel jamming, or issues with landing gear retraction and extension.
Causes of failure include general wear, out-of-round components, internal component defects (e.g., missing parts, jammed orifices), or physical damage like bent or broken rods.
Incidents frequently lead to aborted takeoffs, returns to base, and necessitate component replacement or upgrades, with one case resulting in an emergency landing.

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Cessna 208A Cargomaster

Failed Shimmy Dampener

During takeoff roll, the crew experienced a severe nosewheel shimmy at approximately 40 knots and aborted takeoff. Troubleshooting revealed a failed shimmy dampener (p/n 26940022). Removed old-style shimmy dampener and replaced with upgraded Lord component (p/n SE0170-7) per SK208-164A. Ops and taxi checks performed with no defects.

Part total time: 718.0 hours

Cessna 208B Grand Caravan

Nose-Gear Vibration

Pilot reported severe vibration during the takeoff roll and aborted. Troubleshooting and inspection of main landing gear mounting points and engine mounting collar with no discrepancies found. Found the nose tire out of round and a faulty shimmy dampener. Nose tire assembly was repaired and the shimmy dampener replaced under K208-164A.

Part total time: 2534.0 hours

Pilatus PC-12/45

Jammed Shimmy Dampener

Shimmy dampener would not pass test per component maintenance manual; internals were jammed. Upon teardown, inspection revealed several missing parts within unit. Due to missing parts, the orifice was jammed sideways. Also, an incorrect roll pin retainer was installed instead of a solid pin.

Part total time: Unknown

Piper PA-31-350 Navajo Chieftain

Malfunctioning Shimmy Dampener

Bent shimmy dampener rod (p/n 01500100) caused nosewheel to jam to its maximum right deflection. When the landing gear was retracted, misalignment of the aligner assembly and the guide bracket occurred. Gear selection up or down was affected and resulted in an emergency landing with an unlocked nose-down configuration.

Part total time: Unknown

Piper PA-31-350 Navajo Chieftain

Broken Shimmy Dampener

After takeoff, when retracting the gear, the nose gear did not fully retract. Crew cycled gear back to the extended position and returned to base. Examination revealed the shimmy dampener rod end broke, causing nose gear to jam in wheel well. Removed and replaced component and nose gear assembly.

Part total time: Unknown

Piper PA-34-200T Seneca II/III

Broken Shimmy Dampener

During a pre-flight walk-around inspection, the student pilot noted the shimmy dampener (p/n 6801400) was at an awkward angle. Examination revealed the shaft was broken next to the rod end. No other visible damage was evident. The part was replaced.

Part total time: Unknown