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could aggravate a fuel imbalance. This practice is especially significant if an
engine failure occurs and a fuel leak is present. Arbitrarily opening the crossfeed
valve and starting fuel balancing procedures without following the checklist can
result in pumping usable fuel overboard.
October 31, 2004
767 Flight Crew Training Manual
Non-Normal Operations
Copyright © The Boeing Company. See title page for details.
FCT 767 (TM) 8.17
The misconception may be further reinforced during simulator training. The fuel
pumps in simulators are modeled with equal output pressure on all pumps so
opening the crossfeed valve appears to maintain a fuel balance. However, the fuel
pumps in the airplane have allowable variations in output pressure. If there is a
sufficient difference in pump output pressures and the crossfeed valve is opened,
fuel feeds to the operating engine from the fuel tank with the highest pump output
pressure. This may result in fuel coming unexpectedly from the tank with the
lowest quantity.
Note: It is not necessary to terminate fuel balancing on final approach.
Fuel Balancing Considerations
The crew should consider the following when performing fuel balancing
procedures:
• use of the Fuel Balancing Supplementary Procedure in conjunction with
good crew coordination reduces the possibility of crew errors
• routine fuel balancing when not near the imbalance limit increases the
possibility of crew errors and does not significantly improve fuel
consumption
• during critical phases of flight, fuel balancing should be delayed until
workload permits. This reduces the possibility crew errors and allows
crew attention to be focused on flight path control
• fuel imbalances that occur during approach need not be addressed if the
reason for the imbalance is obvious (e.g. engine failure or thrust
asymmetry, etc.).
Fuel Leak
Any time an unexpected fuel quantity indication, FMC or EICAS fuel message, or
imbalance condition is experienced, a fuel leak should be considered as a possible
cause. Maintaining a fuel log and comparing it to the flight plan can help the pilot
recognize a fuel leak.
Significant fuel leaks, although fairly rare, are difficult to detect. The NNC
assumes the leak is between the strut and the engine. There is no specific fuel leak
annunciation on the flight deck. A leak must be detected by discrepancies in the
fuel log, by visual confirmation, or by some annunciation that can occur because
of a leak. Any unexpected change in fuel quantity or fuel balance should alert the
crew to the possibility of a leak. If a leak is suspected, it is imperative to follow
the NNC
Low Fuel
A low fuel condition exists when the FUEL CONFIG light illuminates and the
EICAS message LOW FUEL is displayed.
October 31, 2004
767 Flight Crew Training Manual
Non-Normal Operations
Copyright © The Boeing Company. See title page for details.
8.18 FCT 767 (TM)
Approach and Landing
With a low fuel quantity, the clean configuration should be maintained as long as
possible during the descent and approach to conserve fuel. However, initiate
configuration change early enough to provide a smooth, slow deceleration to final
approach speed to prevent fuel running forward in the tanks.
A normal landing configuration and appropriate airspeed for the wind conditions
are recommended.
Runway conditions permitting, heavy braking and high levels of reverse thrust
should be avoided to prevent uncovering all fuel pumps and possible engine
flameout during landing roll.
Go-Around
If a go-around is necessary, apply thrust slowly and smoothly and maintain the
minimum nose-up body attitude required for a safe climb gradient. Avoid rapid
acceleration of the airplane. If any wing tank fuel pump low pressure light
illuminates, do not turn off fuel pump switches.
Fuel Jettison
Fuel jettison should be considered when situations dictate landing at high gross
weights and adequate time is available to perform the jettison. When fuel jettison
is to be accomplished, consider the following:
• ensure adequate weather minimums exist at airport of intended landing
• fuel jettison above 4,000 feet AGL ensures complete fuel evaporation
• downwind drift of fuel may exceed one mile per 1,000 feet of drop
• avoid jettisoning fuel in a holding pattern with other aircraft below.
Hydraulics
Proper planning of the approach is important. Consideration should be given to the
effect the inoperative system(s) has on crosswind capabilities, autoflight,
stabilizer trim, control response, control feel, reverse thrust, stopping distance,
　
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