As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 4067 - DURING TAXI, THE NR 4 MAIN WHEEL CAME OFF. AIRCRAFT PROCEEDED TO GATE AND PASSENGERS DEPLANED NORMALLY. INVESTIGATION OF FAILURE SHOWED THE AXLE HAD BROKEN JUST INSIDE THE OUTER BEARING SURFACE. A NEW LANDING GEAR WAS INSTALLED AND RETRACTION CHECKED SATISFACTORY. THE AIRCRAFT RETURNED TO SERVICE. SIMMONS ENGINEERING DEPT AND MESSIER ARE CONTINUING THE EVALUATION OF ASSY TO DETERMINE CAUSE OF FAILURE. (M)