NTSB Identification: LAX93IA245.
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Scheduled 14 CFR operation of UNITED AIRLINES
Incident occurred Tuesday, June 08, 1993 in LOS ANGELES, CA
Probable Cause Approval Date: 08/01/1994
Aircraft: BOEING 757-222, registration: N540UA
Injuries: 197 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.

The aircraft was climbing through 25,000 feet in light turbulence when the crew felt two jolts and heard a loud explosive noise followed by a sharp roll to the left. A visual inspection revealed that the left overwing emergency escape slide deployed and separated in flight. The crew returned to Los Angeles and made an uneventful landing. Post incident examination revealed that the slide compartment door was unlatched and open, and, the adjacent maintenance access door was open, with the latching handle in the unlocked position. The flight prior to the incident one had experienced two EICAS warning messages concerning the left overwing slide door. After landing, maintenance personnel accessed the compartment, cleaned a proximity switch then functionally tested the system. The flight was then dispatched with no open items. The maintenance closing procedure in effect at the time of the incident called for one mechanic to hold the bottom corners of the 33 inch wide slide door closed while manipulating the latching handle in a maintenance access door 12 inches aft of the slide door. The procedure has since been changed to require two mechanics, one to hold the door closed while the second manipulates the latching handle.

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

the inadvertent deployment of an overwing emergency excape slide due to the inadequate latching of the slide compartment door following access by maintenance personnel. A factor in the accident was the inadequate door closing procedure specified by the manufacturer and the airline in the maintenance instructions.

Full narrative available

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