B737-400
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Aircraft Aircraft Damaged; Flight Crew Returned To Gate; General Flight Cancelled / Delayed; General Maintenance Action
Human Factors
Taxiout; heard/felt loud bump. Stopped the aircraft. Noticed wheel assembly; rim/hubcap passing the aircraft on the right and hit the Wheel Well/Landing Gear Assembly of a CRJ-900 aircraft waiting on taxiway. Maintenance and/or mechanical failure. Gate return. Flight delay.
Reporter stated the airport they were departing from has a history of nasty holes in some of the taxi ramps to the runways.  However; no potholes existed where they were taxiing; so he was surprised to hear and feel the loud bump. That's when his First Officer commented about seeing a tire roll past him; they both then watched their right-hand Main Landing Gear (MLG) Outboard (O/B) tire roll into the forward side of the left MLG on the waiting CRJ-900 aircraft.Reporter stated the aircraft was not in a turn; but 'dead straight' on the taxiway at Max Gross limits of approximately 130;000 to 140;000lbs (pounds). Maintenance arrived but refused to move the B737 aircraft until all the passengers were deplaned. Maintenance would not put another tire on the same O/B axle due to concerns that the axle may have fractured. Customer Service wanted to de-board the passengers and have them take all their carry-on luggage; handbags; including five wheelchair bound passengers and have them walk across the taxi ramp to the Terminal.  He refused to order the de-planing for safety concerns until buses were brought to the aircraft. Maintenance showed him where the Wheel Tie-bolts holding the two wheel halves together had sheared; allowing the air in the tire to blow-out; separating the O/B wheel half from the wheel assembly and axle; while also blowing and rolling the tire off the remaining wheel half that was still on the axle; due to the aircraft had not yet stopped; eventually rolling into the CRJ-900 aircraft. At that time; the O/B Main tire; O/B wheel half had not been located. The tire was serviceable; not worn. Questions about possible corroded wheel Tie-bolts or cracks in the wheel halves have not been answered.  No damage occurred to the CRJ-900 aircraft.
A Captain reports that during taxi-out; he felt and heard a loud bump and noticed a Main Landing Gear (MLG) tire passing his B737-400 aircraft and striking the Main Landing Gear of a waiting CRJ-900 aircraft.