C140 intermittent noise on rollout

GeorgeC

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GeorgeC
On the landing rollout, sometimes I hear a noise. Not quite grinding, not quite scraping... sounds like I'm dragging a chain behind the plane. It's intermittent. Control inputs or brakes do not seem to affect it, it just comes and goes. New Lang tailwheel. I repacked the bearing, the races were smooth, no signs of seizure or chattering. I never notice it when taxiing to depart, only at slow speeds when I'm wrapping up the landing or taxiing back. I'm out of ideas.
 
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Having both of your sunvisors down caused the camera to crank up the exposure.



The windshield takes up a larger percentage of the image than in your video so the exposure is better balanced between inside and outside.

It's also usually easier to lighten dark areas in post-production than darken light areas.
I'd think front wheel bearings or brakes as well.
 
Main gear bearings were inspected/repacked at annual and were reported to be in good shape. Both brakes were serviced just prior to that. The noise sounds like it's coming from the back.
 
any chance u could set up a gopro pointing to where u think it's coming from?
 
The Lang tailwheel is solid, correct? I've found that to be a source of noise in almost every plane I've flown with one. It causes a resonation in the fuselage, but only at certain speeds. Try to safely push the stick forward to remove some of the weight from the tailwheel and see if it changes.
 
Yes, the Lang is solid.

I got to monkey with it a bit on Saturday. Forward stick to lighten the tail didn't do anything. At one point, though, if I applied light pressure to both brakes, I could deaden whatever it was that was buzzing or vibrating. I don't know if it was the brakes themselves or just the fact that I had slowed; if I taxi slowly enough, it doesn't happen at all.
 
You didn't say what aircraft. I flew a Cessna 172 Saturday that had a noise similar to what you describe. It was the metal fairing on the right gear leg.
 
yeah...sorry, noticed in the title right after I hit the "post reply" button.
 
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The Lang tailwheel is solid, correct? I've found that to be a source of noise in almost every plane I've flown with one. It causes a resonation in the fuselage, but only at certain speeds. Try to safely push the stick forward to remove some of the weight from the tailwheel and see if it changes.

The solid tailwheel can be noisy, especially on grooved pavement.
 
I think they are Clevelands.
 
Apparently improperly-riveted linings can make noise. This would be consistent with the noise going away when I get on the brakes.

http://www.rapcoinc.com/pdf/Informational Tips/Brake Troubleshooting Tips.pdf
Problem:
6.
Brake lining cracks or makes squealing sound.
Cause:
Cracked linings can result from the use of a hammer type rivet set.
For proper installation a screw type rivet tool such
as the RAPCO RA825 is recommended.
The other major cause of cracked linings comes from warped
or damaged back plates and pressure plates. They do
not fully contact the lining material to offer proper support
or thermal conductivity. In addition a small mound of metal
or a burr will develop around the rivet hole (Figure 3). It can
cause the lining to crack when riveted or if it does wear
into the lining, it will leave the lining loose which can set
t up a high frequency vibration resulting in a squeal sound.
When installing new linings always clean the back plates and
pressure plates then use a straight edge to assure that
the surfaces that mate with the linings are flat.
 
I chased an intermittent noise in a 150 for some time, and eventually found that the inner race of the outer bearing cone in the right main was cracked. That race will slowly creep around the axle in service, and when the crack was at the bottom, where the rollers were bearing the airplane's weight on it, it would make a rumble as the rollers passed over the crack. Very rare. Such noise can resonate all through the airframe, deceiving one as to its origin.

Any pitting in any bearing race or roller will also make various noises. Any discoloration of a bearing should be enough cause to replace it. Aircraft wheel bearings are subject to corrosion since the wheel seals are still made of felt, something the automobile industry abandoned 100 years ago, and as an owner washes his airplane he'll often squirt water at the wheel hubs. It gets past those felt seals real easy, mixes with the grease (which is just thickened oil) and forms acids that corrode........

......here we go again.......:popcorn:
 
Main gear bearings were inspected/repacked at annual and were reported to be in good shape. Both brakes were serviced just prior to that. The noise sounds like it's coming from the back.
Turns out the preload on the right main was wrong.
 
Turns out the preload on the right main was wrong.
As simple as that. Our Skyhawk would make noise after sitting for a couple of weeks in certain weather with the parking brake engaged. Rust on the rotor, except where the pads were touching, made a rhythmic sound.
 
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