NTSB Identification: DEN90IA189.
The docket is stored on NTSB microfiche number 43591.
Scheduled 14 CFR operation of UNITED AIRLINES
Incident occurred Wednesday, September 19, 1990 in DENVER, CO
Probable Cause Approval Date: 05/10/1993
Aircraft: BOEING 737-222, registration: N9044U
Injuries: 2 Minor,94 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

SHORTLY AFTER PUSHBACK IT WAS NOTICED THAT THE #2 ENG DOOR 2 RIGHT HANDLE WAS NOT FLUSH. THE ENG WAS SHUT DOWN AND GROUND MAINT PERSONNEL CLOSED THE DOOR FROM THE OUTSIDE. THE CABIN THEN BEGAN TO FILL WITH DENSE SMOKE. THE CAPTAIN, USING RADIO AND AN OPEN WINDOW, WAS UNSUCCESSFUL IN GETTING A JETWAY TO THE AIRPLANE, AND THE CREW AND PAX EXITED USING SLIDES. IT WAS LATER DETERMINED THAT THE BATTERY BUSS RELAY (R1) AND BATTERY TRANSFER RELAY (R2) HAD FAILED. THE AIRPLANE HAD BEEN PUSHED BACK AT GATE B-8, AND HAD RECEIVED CLEARANCE TO GATE B-20 FOR THE EVACUATION. THERE WAS NO JETWAY OPERATOR PRESENT, AND GROUND PERSONNEL ARE NOT CROSS-TRAINED TO OPERATE A JETWAY. WHEN THE #2 ENG WAS SHUT DOWN, THE ELECTRICAL TRANSFER SYSTEM PICKED UP THE LOAD. THE FLIGHTCREW DID NOT POWER THE RIGHT BUS FROM THE APU.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

THE FAILURE OF THE FLIGHT CREW TO FOLLOW EMERGENCY PROCEDURES/DIRECTIVES. FACTORS WERE THE FAILURE OF THE AIRCRAFT ELECTRICAL SYSTEM (RELAYS) AND THE FAILURE OF THE COMPANY TO PROVIDE A JETWAY OPERATOR.

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