AIRCRAFT FUEL VARIABLES

The tables below indicate the properties for the Simulation Variables that can be used to get and set variables related to the fuel system of the aircraft. For information on the units listed for each variable, please see here: Simulation Variable Units

NOTE: When Microsoft Flight Simulator is running in multiplayer mode, only a small number of variables are communicated between aircraft. Those variables that are available will say so in the description as being either for "All Aircraft" or for "Shared Cockpit".

You can find a complete index of all available SimVars here: SimVar Index

 

 

General

The majority of these SimVars are only valid for legacy aircraft that have set up their fuel using the [FUEL] section of the flight model CFG file. Aircraft in Microsoft Flight Simulator should not be using this fuel method nor these SimVars, and should instead be defining things using the [FUEL_SYSTEM] section of the CFG file and the Fuel System SimVars.

 

Simulation Variable Description Units Settable
FUEL CROSS FEED:index Cross feed valve setting. This will return the current setting for the fuel crossfeed for the indexed engine, based on the current status of the simulation and the Cross Feed key events.

Enum:

  1. 0 = Closed
  2. 1 = Open
  3. 2 = Left to Right
  4. 3 = Right to Left
FUEL DUMP ACTIVE If 1 (TRUE) then the aircraft can dump fuel. Bool
FUEL DUMP SWITCH If set to 1 (TRUE) then the aircraft will dump fuel at the rate set by fuel_dump_rate parameter in the flight_model.cfg file. Bool
FUEL LEFT CAPACITY Maximum capacity in volume of all the tanks on the left side of the aircraft. Gallons
FUEL LEFT QUANTITY Current quantity in volume of all the tanks on the left side of the aircraft. Gallons
FUEL PUMP Currently not used within the simulation. Number
FUEL RIGHT CAPACITY Maximum capacity in volume of all the tanks on the right side of the aircraft. Gallons
FUEL RIGHT QUANTITY Current quantity in volume of all the tanks on the right side of the aircraft. Gallons
FUEL SELECTED QUANTITY:index Quantity of fuel in the tank referenced by the indexed selector. When using the legacy fuel system, this SimVar will return the quantity of fuel in the tank pointed to by the selector you chose with the index. If passing an index higher than the number of selectors - or when using the modern fuel system - it will return the total fuel quantity available. Gallons
FUEL SELECTED QUANTITY PERCENT:index Percent or capacity for the tank referenced by the indexed selector. When using the legacy fuel system, this SimVar will return the percentage of fuel in the tank pointed to by the selector you chose with the index. If passing an index higher than the number of selectors available - or when using the modern fuel system - it will return the percentage of total fuel quantity available. Percent Over 100
FUEL SELECTED TRANSFER MODE

The method of transfer for the fuel. Each of the available transfer options are explained below:

  • off - Fuel transfer is switched off.
  • auto - Automatically balance the fuel between the Center1 and Center2 tanks to maintain the center of gravity.
  • forward - Fuel will be transferred forwards from the Center1 tank to the Center2 tank.
  • aft - Fuel will be transferred aftwards from the Center2 tank to the Center1 tank.
  • manual - Fuel will be transferred for 1 second from the Center1 tank to the Center2 tank at a rate of 1lbs/s.
  • custom - This requires one or more pumps to have been defined using the fuel_transfer_pump.N parameter in the flight_model.cfg file, as well as their associated electrical circuits.

Enum:

  1. 0 = off
  2. 1 = auto
  3. 2 = forward
  4. 3 = aft
  5. 4 = manual
  6. 5 = custom
FUEL TOTAL CAPACITY Total fuel capacity of the aircraft for all tanks. Gallons
FUEL TOTAL QUANTITY Current total quantity of fuel in volume for all tanks of the aircraft. Gallons
FUEL TOTAL QUANTITY WEIGHT Current total fuel weight for all tanks of the aircraft Pounds
FUEL TRANSFER PUMP ON:index Returns 1 (TRUE) if the indexed pump is active. Bool
FUEL WEIGHT PER GALLON The weight of the fuel, per gallon. Pounds
NEW FUEL SYSTEM Will return 1 (TRUE) if the aircraft is using the modern [FUEL_SYSTEM] or 0 (FALSE) for the legacy [FUEL]. Bool
NUM FUEL SELECTORS The number of fuel selectors on the aircraft. Number
UNLIMITED FUEL Will return 1 (TRUE) if the unlimited fuel flag has been enabled, or 0 (FALSE) otherwise. Bool
UNUSABLE FUEL TOTAL QUANTITY The total amount of fuel in all tanks of the aircraft which is not usable. Gallons

 

 

Fuel System

These SimVars are dedicated to controlling the modern component fuel system, which you can set up in the [FUEL_SYSTEM] section of the flight_model.cfg. All aircraft made for Microsoft Flight Simulator should be using this system and these SimVars, and only legacy aircraft should be using the General SimVars and the [FUEL] section of the flight_model.cfg file.

 

Simulation Variable Description Units Settable
FUELSYSTEM ENGINE PRESSURE:index The pressure of the fuel coming to the indexed engine. The index is the number of the engine N component as defined by the Engine.N parameter. Kilo pascal
FUELSYSTEM JUNCTION SETTING:index This will return the current Option for the indexed junction. The index is the number of the line N component as defined by the Junction.N parameter. Number
FUELSYSTEM LINE FUEL FLOW:index The fuel flowing through the indexed line in Gallons per Hour. The index is the number of the line N component as defined by the Line.N parameter. Gallons per hour
FUELSYSTEM LINE FUEL LEVEL:index The level of fuel in the indexed line in Gallons. The index is the number of the line N component as defined by the Line.N parameter. Gallons
FUELSYSTEM LINE FUEL PRESSURE:index The pressure in the indexed fuel line, measured in KiloPascal. The index is the number of the line N component as defined by the Line.N parameter. Kilo pascal
FUELSYSTEM PUMP ACTIVE:index Whether or not the indexed pump is actually active. The index is the number of the pump N component as defined by the Pump.N parameter. Bool
FUELSYSTEM PUMP SWITCH:index Whether or not the indexed pump is enabled. The index is the number of the pump N component as defined by the Pump.N parameter. Bool
FUELSYSTEM TANK CAPACITY:index

Total capacity of the indexed fuel tank. The index is the number of the tank N component as defined by the Tank.N parameter.

NOTE: This SimVar can only be used with the modern Fuel System.

 Gallons
FUELSYSTEM TANK LEVEL:index

Quantity of fuel available in the indexed fuel tank. The index is the number of the tank N component as defined by the Tank.N parameter.

NOTE: This SimVar can only be used with the modern Fuel System.

 Percent Over 100
FUELSYSTEM TANK QUANTITY:index

Quantity of fuel currently available in the indexed fuel tank. The index is the number of the tank N component as defined by the Tank.N parameter.

NOTE: If the fuel system Version is 2 or below, the index value will be one of the Fuel Tank Selection indices.

 Gallons
FUELSYSTEM TANK TOTAL QUANTITY:index

Total quantity of fuel available in the indexed fuel tank, including any unusable fuel. The index is the number of the tank N component as defined by the Tank.N parameter.

NOTE: If the fuel system Version is 2 or below, the index value will be one of the Fuel Tank Selection indices.

 Gallons
FUELSYSTEM TANK WEIGHT:index

Weight of fuel available in the indexed fuel tank. The index is the number of the tank N component as defined by the Tank.N parameter.

NOTE: If the fuel system Version is 2 or below, the index value will be one of the Fuel Tank Selection indices.

 Pounds
FUELSYSTEM TRIGGER STATUS:index Whether or not the indexed trigger is active. The index is the number of the trigger N component as defined by the Trigger.N parameter. Bool
FUELSYSTEM VALVE OPEN:index Whether or not the indexed valve is actually fully opened. The index is the number of the valve N component as defined by the Valve.N parameter. Percent Over 100
FUELSYSTEM VALVE SWITCH:index Whether or not the indexed valve is set to be opened. The index is the number of the valve N component as defined by the Valve.N parameter. Bool

 

 

Fuel Tanks

Simulation Variable Description Units Settable

FUEL TANK CENTER CAPACITY

FUEL TANK CENTER2 CAPACITY

FUEL TANK CENTER3 CAPACITY

 Maximum capacity in volume of center tank 1/2/3. Gallons

FUEL TANK CENTER LEVEL

FUEL TANK CENTER2 LEVEL

FUEL TANK CENTER3 LEVEL

 Percent of maximum capacity of center tank 1/2/3. Percent Over 100

FUEL TANK CENTER QUANTITY

FUEL TANK CENTER2 QUANTITY

FUEL TANK CENTER3 QUANTITY

 Current quantity in volume of center tank 1/2/3. Gallons

FUEL TANK EXTERNAL1 CAPACITY

FUEL TANK EXTERNAL2 CAPACITY

 Maximum capacity in volume of external tank 1/2. Gallons

FUEL TANK EXTERNAL1 LEVEL

FUEL TANK EXTERNAL2 LEVEL

 Percent of maximum capacity of texternal tank 1/2. Percent Over 100

FUEL TANK EXTERNAL1 QUANTITY

FUEL TANK EXTERNAL2 QUANTITY

 Current quantity in volume of external tank 1/2. Gallons
FUEL TANK LEFT AUX CAPACITY Maximum capacity in volume of the left auxiliary tank. Gallons
FUEL TANK LEFT AUX LEVEL Percent of maximum capacity of the left auxiliary tank. Percent Over 100
FUEL TANK LEFT AUX QUANTITY Current quantity in volume of the left auxiliary tank. Gallons
FUEL TANK LEFT MAIN CAPACITY Maximum capacity in volume of the left main tank. Gallons
FUEL TANK LEFT MAIN LEVEL Percent of maximum capacity of the left main tank. Percent Over 100
FUEL TANK LEFT MAIN QUANTITY Current quantity in volume of the left main tank. Gallons
FUEL TANK LEFT TIP CAPACITY Maximum capacity in volume of the left tip tank. Gallons
FUEL TANK LEFT TIP LEVEL Percent of maximum capacity of the left tip tank. Percent Over 100
FUEL TANK LEFT TIP QUANTITY Current quantity in volume of the left tip tank. Gallons
FUEL TANK RIGHT AUX CAPACITY Maximum capacity in volume of the right auxiliary tank. Gallons
FUEL TANK RIGHT AUX LEVEL Percent of maximum capacity of the right auxiliary tank. Percent Over 100
FUEL TANK RIGHT AUX QUANTITY Current quantity in volume of the right auxiliary tank. Gallons
FUEL TANK RIGHT MAIN CAPACITY Maximum capacity in volume of the right main tank. Gallons
FUEL TANK RIGHT MAIN LEVEL Percent of maximum capacity of the right main tank. Percent Over 100
FUEL TANK RIGHT MAIN QUANTITY Current quantity in volume of the right main tank. Gallons
FUEL TANK RIGHT TIP CAPACITY Maximum capacity in volume of the right tip tank. Gallons
FUEL TANK RIGHT TIP LEVEL Percent of maximum capacity of the right tip tank. Percent Over 100
FUEL TANK RIGHT TIP QUANTITY Current quantity in volume of the right tip tank. Gallons
FUEL TANK SELECTOR:index

Which tank the indexed selector is set to. The index is the selector to check (from 1 to 4), and the return value will be the Fuel Tank Selection index.

NOTE: This SimVar is only valid for the legacy [FUEL] setup.

 Enum

 

 

Fuel Tank Selection

Number Description
0 Off
1 All
2 Left
3 Right
4 Left auxiliary
5 Right auxiliary
6 Center
7 Center2
8 Center3
9 External1
10 External2
11 Right tip
12 Left tip
13 Crossfeed
14 Crossfeed left to right
15 Crossfeed right to left
16 Both
17 External
18 Isolate
19 Left main
20 Right main