A couple of months ago the right brake on my Legacy RG developed a vibration.  Upon initial braking shortly after touchdown, the brakes were smooth.  However, after a second or so of braking, the right main landing gear started vibrating.  Releasing brake pressure immediately made the vibration go away.  If it had been a car, I would have said the rotor was warped.  I jacked up the airplane and checked the run-out of the disk with a dial indicator.  It was true within .002".  Of course, that was with a room temperature disk.

 

I called Cleveland tech support and was told the most likely fix was to replace the brake disk.  I replaced both disks and the vibration disappeared.  Measuring the old disks, there was significant "coning," in which the disk is thicker at the outside edge than near the axle.  Cleveland's coning limit for my disks was .015" and the right brake on mine was .025".  The disk still met the spec for total thickness.

 

I've got about 660 hours on the Cleveland brakes and maybe a thousand landings.  (You'd think I'd make better landings with that much practice!)  I'm surprised that my brake disks wore out so quickly.  On the other hand, I typically fly out of shorter runways at higher density altitudes, so maybe it's just a lot of heavy braking.

 

Dennis

Legacy RG 660 hours