Accident Boeing 767-233 C-GAUN,

ASN Wikibase Occurrence # 327590

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Date:	Saturday 23 July 1983
Time:	08:40
Type:	Boeing 767-233
Owner/operator:	Air Canada
Registration:	C-GAUN
MSN:	22520/47
Year of manufacture:	1983
Engine model:	Pratt & Whitney JT9D-7R4D
Fatalities:	Fatalities: 0 / Occupants: 69
Aircraft damage:	Substantial, repaired
Category:	Accident
Location:	Gimli Airport, MB (YGM) - Canada
Phase:	En route
Nature:	Passenger - Scheduled
Departure airport:	Ottawa International Airport, ON (YOW/CYOW)
Destination airport:	Edmonton International Airport, AB (YEG/CYEG)
Investigating agency:	CoI
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Boeing 767 C-GAUN was one of four brand new 767's delivered to Air Canada at the time of the accident. On July 22, 1983 C-GAUN underwent a routine service check in Edmonton Airport (YEG), Canada. During this check the three fuel quantity indicators, situated on an overhead panel between the two pilots, were found to be blank. The technician found that he could obtain fuel indication by pulling and deactivating the channel 2 circuit breaker. He marked the circuit breaker 'inoperative' and made an entry in the log book. Because the fuel quantity system was not redundant anymore, the fuel load had to be confirmed by the use of the fuel measuring sticks located under the wings of the aircraft.
The following day the 767 was flown to Montreal via Ottawa (YOW). A crew change took place for the return flight, AC143 to Edmonton. Before the new flight crew arrived on board, a technician entered the cockpit. He noted the entry made in the log book and saw the circuit breaker which had been pulled and tagged. He was confused by the entry in the log book which did not appear to coincide with what he had been taught about the processor in recent training. Because of his confusion, he attempted a self-test of the system and reset the number 2 channel circuit breaker. This caused the fuel gauges in the cockpit to go blank. Not being satisfied with the test, he decided that the ´Fuel Quantity Information System Processor´ had to be replaced. However, none were available in Montreal. On returning to the flight deck, the technician was distracted by the arrival of the fueller and forgot to pull the number 2 circuit breaker again. When the captain for the return flight arrived on board, he saw the blank fuel gauges. This did not surprise him. In a brief conversation with the arriving crew, he was told that the fuel gauges were inoperative and that a fuel drip had to be done to ascertain the amount of fuel on the aircraft. Similarly, the log book entry further confirmed his false assumption about the fuel gauges.
The captain then consulted the Minimum Equipment List (MEL), which clearly indicates that the aircraft was not legal to go with blank fuel gauges. Nevertheless, because of the mistaken assumption already in his mind, the captain formed the opinion that he could safely take and fly the aircraft, provided the fuel quantity on board the aircraft was confirmed by use of the fuel quantity measuring sticks in the fuel tanks. Because of the problem with the gauges, it was decided to load enough fuel to go right through to Edmonton with a drip check to be made both in Montreal and in Ottawa.
Maintenance crew at Montreal calculated the 767's fuel load by hand. They dripped the tanks and the flightcrew calculated the total amount of fuel by using 1.77 pounds/litre as the specific gravity factor. This was the factor written on the refueler's slip and used on all of the other planes in Air Canada's fleet. On the all-metric Boeing 767 however they should have used 0.8 kg/litre of kerosene. The aircraft departed Montreal and landed at Ottawa, a scheduled stop on its way to Edmonton. At Ottawa the plane was re-dripped and the crew were told 11,430 liters of fuel were on board. The flightcrew then thought they had 20,400 kilos of fuel (instead of only 9144 kilos !). This amount was entered in the FMS. En route to Edmonton, at FL410, the EICAS warned low fuel pressure in the left fuel pump. The captain at once decided to divert the flight to Winnipeg, then 120 miles (192 km) away, and commenced a descent. Within seconds, warning lights appeared indicating loss of pressure in the right main fuel tank. Within minutes, the left engine failed, followed by failure of the right engine. The aircraft was then at 35,000 feet, 65 miles (104 km) from Winnipeg and 45 miles (72 km) from Gimli. Without power to generate electricity all the electronic gauges in the cockpit became blank, leaving only stand-by instruments, consisting of a magnetic compass, an artificial horizon, an airspeed indicator and an altimeter. Vectors were given to Gimli. The captain, who had flying experience on a glider, used gliding techniques to manoeuver the airplane for the approach. The landing gear was lowered, but the nose gear could not be lowered and locked. The 767 touched down on runway 32L within 800 feet of the threshold. The nose contacted the runway and the airplane came to rest short of a part of the runway which was at the time being used as a drag racing strip.

Accident investigation: