DURING GND STOP AT ORD MD80 HAS APU FAIL WITH BOTH ENGS SHUT DOWN.

Narrative

AFTER BEING NOTIFIED OF A DEST GND STOP; WE SHUT DOWN BOTH ENGS WITH THE APU RUNNING WHILE PARKED IN THE TXWY B PENALTY BOX AT ORD. 10 MINS LATER THE APU HAD AN INTERMITTENT FAULT CAUSING IT TO INTERMITTENTLY SHUT DOWN. WE ATTEMPTED TO START THE L ENG WHILE IT WAS DOING THIS INTERMITTENT SHUTDOWN CYCLING; BUT THE CTL VALVE WAS CLOSED ALLOWING NO AIR FLOW FOR THE START. AFTER SEVERAL CYCLES THE CAPT SHUT DOWN THE APU RESULTING IN THE ACFT REVERTING TO EMER BATTERY PWR ONLY. HE ATTEMPTED TO RESTART THE APU BUT IT WOULD HANG UP AT 55%. WE CALLED ORD MAINT TO EITHER BRING A TUG TO TOW US IN OR BRING AN ACFT TO START ONE OF THE ENGS. THEY HAD TO COORD WITH THE ARPT AUTH TO GET AN ESCORT FOR EQUIP AND PERSONNEL. AFTER WAITING ON AN ACFT FOR 1 HR WITH NO VENTILATION; THE PARTY ARRIVED AFTER WHICH WE STARTED THE L ENG AND TAXIED BACK TO THE GATE. THE FLT WAS SUBSEQUENTLY CANCELED. OBSERVATIONS: HAD NO PRIOR INDICATION APU WOULD FAIL. IT IS COMMON PRACTICE TO HAVE BOTH ENGS OFF WITH APU RUNNING DURING EXTENDED GND STOPS. A TOW BACK TO THE GATE WOULD HAVE BEEN QUICKER AND USED LESS GND PERSONNEL VERSUS ROUNDING UP AN AIR CART AND GPU ALONG WITH MAINT PERSONNEL.