weird vibration

ScottK

ScottK

Pre-takeoff checklist
Joined
Sep 12, 2011
Messages
427
Location
SW PA
Display Name
Display name:
ScottK
I had just touched down (C172) and was resetting the flaps/carb heat/trim while rolling. As I steered the plane back to the center line a bit, I had a strange vibration in both pedals. It only lasted a second or two. I put the brakes on to slow down and it went away. I taxied off the runway and tried to duplicate it on the taxiway. I couldn't make it happen again. Any ideas as to what it may have been?
 
It's the airplane punishing you for not doing a full stall landing and/or not holding the yoke all the way back during roll out. In other words, nosewheel shimmy.
 
Next time try holding the nose off a bit longer. Sometimes if the shimmy is bad enough, it won't subside until you're nearly stopped. Time to get a damper installed.
 
Ryanb said:
Cessna's are notorious for having shimmies.
Click to expand...


Caused by too little rake angle (caster) on the nose strut. They fixed that on some later legacy airplanes like the R182, and shimmy was never a problem there.

The only way to deal effectively with it is to dynamically balance the nosewheel/tire assembly, just like you car's wheels get when you buy new tires. Without it, your steering wheel would be shaking constantly in cruise, with some particular speed being real bad. Most nosewheels get no balance at all, either static or dynamic, and a static balance will do little or nothing for shimmy, and in some cases will make it worse. There are lots of POA threads on this subject.
 
A couple guys in my club were of the same opinion. Thanks.
 
You must log in or register to reply here.
Back
Top