Incident Summary
A Boeing 767-300R experienced multiple electrical anomalies during en route flight. The flight crew observed illuminated warning lights, erroneous display indications, uncommanded autopilot disconnects, and failure of flight instruments. The flight diverted and subsequently landed with zero flaps and slats extended, thrust reversers inoperative, ground spoilers inoperative, and partial anti-skid. During the landing roll, four main tires failed; four additional tires deflated due to heat-activated fuse plugs. A small fire erupted in the main landing gear area but was extinguished. The flight crew was unaware that the thrust reversers and ground spoilers were inoperative. They noted an ANTI-SKID advisory, but due to the workload of responding to the multiple electrical and system failures, did not respond to it.
Investigation Findings
The investigation revealed that systems on several electrical buses failed or became intermittently inoperative, while other systems on the same buses remained operative. Detailed ground and flight tests were conducted but could not duplicate the anomalies. The investigation determined that the negative cable for the main battery was not positively secured due to a stripped jam nut, and the main battery shunt was not built up in accordance with Boeing specifications. Boeing indicated that a loose battery shunt could cause interruption to ground. Similar events were reported with two other aircraft of the same operator, but a query of the Boeing database did not find similar events. A Boeing 767-300R of another operator, with the same configuration, did not experience similar events.