Re: [Titanaircraft] Vibration on rollout after landing

Also, be sure to look at the tires and look for out of shape. Mine aren't real round anymore, and are evident right after take-off and the wheels still vibrate, if you can stomp on the brakes and it stops,?????

Kess

----- Original Message -----
From: Jim Covington
To: Titanaircraft@yahoogroups.com
Sent: Wednesday, November 18, 2009 5:14 AM
Subject: Re: [Titanaircraft] Vibration on rollout after landing

Main gear leg shimmy/vibration can come from disc brakes when there is a
rough spot on the brake rotor or drum that grabs more than the others.
When this spots rolls around and hits the brake pads, rearward force on
the leg is increased - when the rough spot passes, the leg springs back
forward. If this back/forward frequency (which will depend on
groundspeed) matches the natural spring frequency of the gear leg, the
vibration can quickly get very severe - enough to be described as "violent."

It's very easy to diagnose - look left or right and you'll see one leg
vibrating like a tuning fork. The short-term fix is simple - release the
brakes. The long term fix is almost as simple - turn the rotors/drums or
replace them.

It's very easy to diagnose and doesn't sound like the problem (his
vibration continues after the brakes are released), but I thought I'd
mention it. It could be the problem if his drum brake cables are
sticking and not releasing properly, or if one of his disc brake rotors
has warped.

The easiest way to identify this is to look sideways at the main gear
legs during the vibration - if one's vibrating and the other's not, you
have found the problem.

Kimberly Panos wrote:
>
>
> Gene,
>
> Are you sure it wasn't nosewheel shimmy? Violent shake is typically
> nosewheel shimmy, especially when it gets worse when you add the
> brakes, and doesn't go away when you release them. Applying the brakes
> creates more down force on the front wheel, which will make the
> shaking feel like it's going to buck you out of the cockpit, or tear
> off the the nose or the fuselage from the wing. If that's the problem,
> visit our web site for drawings to stop that.
> http://motionaero.com/Gallery-Gadgets.html
> <http://motionaero.com/Gallery-Gadgets.html>
>
> If it isn't shimmy, balance the tires. Also, if you have drum brakes,
> convert them to disc. The drum brakes are crummy from the start, won't
> stop the plane, the drums aren't round, and wobble. Something to do on
> any aircraft is to tap the brakes lightly after takeoff to stop the
> wheels from spinning.
>
> --Kimberly
>
> ----- Original Message -----
> From: flint7727
> To: Titanaircraft@yahoogroups.com
> <mailto:Titanaircraft%40yahoogroups.com>
> Sent: Tuesday, November 17, 2009 8:59 AM
> Subject: [Titanaircraft] Vibration on rollout after landing
>
> Initial touchdown and rollout is smooth until I begin slowing down and
> that's when it begins to shake/vibrate. It seems to get worse when I
> apply the brakes, but once it starts shaking,it won't stop even if I
> get off the brakes. It stops when I get below 20 mph. This past Sunday
> was the most violent that I've encountered to date. I honestly thought
> the landing gear was going to break, or the engine was going to come
> off. This is not good for any part of the aircraft. Has anyone had
> this problem, and if so, what was the fix.
> Thanks,
>
> Gene
>
> [Non-text portions of this message have been removed]
>
>

[Non-text portions of this message have been removed]

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