David Learmount/LONDON
AN Almost total failure of a Boeing 767's electronic flight instrument system (EFIS) during a transatlantic flight has been attributed to battery installation faults, according to a US National Transportation Safety Board (NTSB) report.
The 28 May, 1996, Martinair Holland 767-300ER flight from Amsterdam Schiphol to Orlando, Florida, was forced to divert to Boston, Massachusetts, with the crew flying manually and using only standby flight instruments. During the flapless landing, the ground spoilers and thrust reversers did not work, four tyres burst and there was a brake fire, but there were no injuries among the 202 people on board.
Tests at Boeing's Seattle plant, where the aircraft was ferried for investigation, indicated that the EFIS was fully serviceable, and Boeing could not replicate the EFIS failure symptoms.
The problems started with the EFIS clocks, which needed resetting before departure. Early in the flight, warning lights illuminated then extinguished, there were uncommanded autopilot disconnects and changes in aircraft zero fuel weight as shown on the control and display unit. Approaching the USA's east coast, the NTSB report says, the display anomalies increased in frequency and duration.
Finally, the captain lost his navigation display and there were frequent losses of the co-pilot's electronic attitude director indicator and electronic horizontal situation indicator. At the same time the engine indicating and crew alerting system screen "-was filled with caution and advisory messages." Upon deploying flaps to position 1, there was an indicated flap asymmetry, so the crew decided to proceed with a flapless landing.
Boeing and the NTSB attributed the in-flight faults to a main battery negative cable which was insecurely attached because of a stripped nut, and a battery shunt which was not fitted to specification. Boeing's database showed two battery shunt problems with other Martinair 767s, but none with any other operator, the NTSB report says.
Source: Flight International
