NTSB Identification: SEA96IA131.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Scheduled 14 CFR operation of DELTA AIR LINES
Incident occurred Wednesday, June 19, 1996 in SALT LAKE CITY, UT
Probable Cause Approval Date: 09/30/1997
Aircraft: Boeing 767-332, registration: N136DL
Injuries: 186 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.
During taxi for departure a 'R GEN OFF' and 'R GEN DRIVE' EICAS message illuminated indicating a malfunction of the right integrated drive generator (IDG), and the crew returned the Boeing 767 to the gate. Maintenance was notified, and a mechanic was dispatched to the aircraft. The mechanic reported that he 'assumed (the) crew had disconnected (the) IDG.' The captain reported that he was advised by the mechanic that 'the IDG is disconnected.' The aircraft was prepared and released according to its MEL for the flight using the left IDG and APU generator. During climbout a 'R STARTER CUTOUT' EICAS message illuminated followed by a fire warning on the right engine. Both fire bottles were exhausted, the fire warning extinguished, and the aircraft was returned to Salt Lake City, for emergency landing on runway 16L. Postincident examination of the engine revealed the fire-damaged remains of the right IDG and its magnesium housing. A download of digital data from the aircraft revealed that the original EICAS and IDG annunciations were related to low oil pressure within the IDG. An FAA inspector, who examined the aircraft immediately following the event, found the right IDG disconnect switch still safety wired (the IDG cannot be disconnected without breaking the wire and depressing the switch). The MEL dispatch procedure developed by the carrier did not address the need to run the associated engine at or above idle in order to successfully disconnect the IDG.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: failure of maintenance personnel to properly disconnect (disengage) the right integrated drive generator (IDG) in compliance with the MEL dispatch procedure, which allowed the right IDG to overheat. Factors relating to the incident were: low oil pressure in the right IDG, and insufficiently defined company developed dispatch procedure. Full narrative available
Index for Jun1996 | Index of months