MD-11 Flight Crew Operations Manual
k
Fuel -
Description and Operation
Fuel.10.15
• During descent, from 26,750 feet till 17,750 feet, if any fuel remains in
the tail tank, tail fuel is transferred forward.
• During approach, tanks 1, 2, and 3 forward and aft pumps are on. Aux
manifold fuel transfer is inhibited.
• After landing, tanks 1, 2, and 3 forward pumps are turned off one minute
after landing, unless the fuel level is less than 5,216 kilograms in a tank.
• After engine shutdown, all main tank pumps are turned off unless the
APU is operating, in which case the tank 2 left aft pump will remain on.
Fuel Scheduling
The FSC checks and maintains the fuel schedule. Fuel management is required to
satisfy aircraft structural load requirements. If fuel is not properly distributed, it
will be rescheduled to the correct tanks. Depending on the total fuel quantity and
distribution when transfer is permitted, the fuel transfer will continue from that
point. The sequence of fuel management is as follows:
• If tail fuel management is not in use, tail tank to upper auxiliary tank,
maintaining the upper auxiliary tank full.
• Lower auxiliary tank to upper auxiliary tank, maintaining the upper
auxiliary tank full.
• Simultaneously with the preceding two functions, upper auxiliary tank to
tanks 1, 2, and 3, maintaining them full.
• Tank 2 to tanks 1 and 3, maintaining them full.
• When tank 2 quantity equals that in 1 or 3, discontinue transfer from tank
2, allowing tanks 1, 2, and 3 to burn down to equal fuel quantities.
• When tanks 1 and 3 tip fuel equals the fuel in the inboard section of the
tank, the tip fuel is mechanically transferred to the inboard section,
keeping it at a constant level of about 2,268 kilograms until the tip fuel is
depleted (FSC monitors but does not perform this action).
• In case of reversion to the manual mode, fuel schedule is still maintained
through float switches.
Tail Fuel Management
The FSC manages the tail fuel. Tail fuel management begins when the climb phase
of flight begins. The primary purpose of tail fuel management is to improve
aircraft cruise performance by maintaining an aft center of gravity (CG). Tail fuel
is managed as follows:
• The CG is controlled to a preselected aft limit. This function is allowed
only if the total fuel quantity exceeds 27,216 kilograms at termination of
refueling. Once the total fuel quantity is below 23,134 kilograms, no
further fuel will be transferred aft for CG control. If engine 2 is shut
down, tail fuel is limited to a maximum of 2,268 kilograms. If the CG
moves aft of the aft control limit, the fuel system controller will revert to
the manual mode and the SEL FUEL SYS MAN alert is displayed.
October 02, 2006
To Next Page
Loading...