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C172 Shimmy

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wrxpilot

The proud, the few
Joined
Jun 26, 2004
Posts
901
One of the 172s I rent has a tendency to shimmy on T/O and landing rollout. It's much more pronounced on T/O, but I can get it to settle out by adding back pressure until I hit a high enough a/s to get rotation (or adding back pressure on rollout until I've slowed past the "critical" shimmy speed). Nonetheless, it is annoying. I've squawked this on the maintenance sheet before, but it always seems to re-appear on this a/c. What is the typical cause of nosewheel shimmy? Is it ever dangerous? Are there any long term effects such as early fatigue on nose gear components?
 
Causes for nose wheel shimmy in Cessna's (partial list)

a) Shimmy dampener requires servicing and/or resealing
b) Shimmy dampener attaching hardware/bushings worn
c) Nose tire out of balance
d) Nose wheel bearings and races worn
e) Nose gear torque links (scissors) bolts/bushings worn
f) Nose wheel fairing (if installed) cracked/broken
g) Spring bungees from rudder pedal torque tube to nose gear horn worn
f) Nose gear to firewall fitting clearance too great, requires reshimming

these are some things that I would normally check, not in this order, and this is just shooting from the hip without examining the aircraft.
 
Sounds like some of the Cessnas I've rented. I used to do soft field TOs with those ones...

However, I did abort one TO because the 182 was shaking so bad my teeth were chattering.

Seems (to me) to be a combination of Cessna design and less-than-stellar maintenance. However, I'm not an A&P (unlike erj-145mech).
 
Last edited:
erj-145mech said:
Causes for nose wheel shimmy in Cessna's (partial list)

a) Shimmy dampener requires servicing and/or resealing
b) Shimmy dampener attaching hardware/bushings worn
c) Nose tire out of balance
d) Nose wheel bearings and races worn
e) Nose gear torque links (scissors) bolts/bushings worn
f) Nose wheel fairing (if installed) cracked/broken
g) Spring bungees from rudder pedal torque tube to nose gear horn worn
f) Nose gear to firewall fitting clearance too great, requires reshimming

these are some things that I would normally check, not in this order, and this is just shooting from the hip without examining the aircraft.


I'm guessing one, or all of the above also.

My first airplane was a 1966 C172 and I had more problems with that shimmy dampener than just about anything else on the airplane, which is why I've never had the desire to own another Cessna single.
 
ERJ already hit the high points. Most of those problems are due to pilot error, either one time or over time. Airplanes would generally do just fine if we could just bump off the pilots...

From your perspective, keeping the weight off the nosewheel is important. Is it dangerous? It can be. But usually it's just annoying.

Keep pressure on both rudder pedals, just like you should in a tailwheel airplane.

If the rental facility can't be bothered to maintain their aircraft, don't you think you might be better served elsewhere?
 
RipCurl said:
Seems (to me) to be a combination of Cessna design and less-than-stellar maintenance. However, I'm not an A&P (unlike erj-145mech).

I've seen a direct cuase/effect relationship between pilots (student and otherwise) landing flat time and time again and nosewheel shimmy in cessna singles.
 
Keep the nosewheel off the ground with backpressure and watch the speed. Most of our Skydogs do the same thing.
 
The 172SP at the place I rent does that periodically. I (and others, based on the logs) squawk it, the mechanic tightens something, it goes away for a few months, then returns. I'd assume some design defect causes one of the previously listed items to repeatedly get out of whack.

When that happens on takeoff, I simply pop the nose early (soft-field) and try to remember to soft-field it on landing (and taxi with the yoke back to remove as much weight as possible from the nosewheel). Write up the notes when I return the plane and it is generally "fixed" the next time I rent it.
 
Coming in for landing once, i set off the ELT because the freakin nosewheel vibrated so bad. It was otherwise a smooth touchdown on the mains and the nosewheel was lowered at a normal rate. I guess the speed was just to fast for the shimmy damper ... but i nearly got a heart attack hearing the ELT in the cockpit. :)
 

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