Procedure for calculating fuel quantity with help of magnetic fuel level indicator.

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Procedure for calculating fuel quantity with help of magnetic fuel level indicator


                                       

                                 Fig 01 Magnetic Level Indicator (MLI)


Please note follow the procedure given in latest revision of AMM. This article is for training purpose.


To watch the video of this blog please click on below link

https://youtu.be/lxX69vkhu0E


To determine fuel quantity in the fuel tank we need to have the information of fuel specific gravity, aircraft attitude and magnetic level indicator reading.



Fig 02 MLI Chart


Above chart given in AMM which shows the fuel quantity in volume. There is different chart for different MLIs. Always refer correct chart for respective MLI. To determine fuel quantity as per this chart we should have the data of aircraft attitude and magnetic level indicator reading.


The three steps for calculating fuel quantity with the help of magnetic fuel level indicator are;

Step 01 Determine Fuel specific gravity

Step 02 Find out aircraft attitude

Step 03 Check the fuel content with MLI


Step 01: Determine Fuel Specific Gravity




Fig 03 Fuel Specific Gravity


Drain the fuel and measure the fuel specific gravity with help of tool as given in AMM.


Step 02: Find out Aircraft Attitude

Due uneven surface of apron, fuel volume does not correct in the tank. aircraft attitude data is important for correctly measure the fuel quantity. There was direct reading aircraft attitude indicator in older aircraft. Now, in new aircraft attitude indicator are eliminated and aircraft attitude data is provided by air data inertial reference unit. (ADIRU)


Procedure to find out equivalent number and letter for pitch and roll data



Fig 04 Alpha Call up pitch and roll data




Fig 05 Fuel Input Parameter


Fig 06 Pitch and Roll Data Table


With help of two method, we can find out aircraft attitude data

1. use of alpha call up feature and

2. Fuel input parameter.

 From any of the given procedure we can find aircraft pitch and roll data that will be some number.

Use the aircraft pitch and roll data to find out equivalent number and letter as given in table.

As  we have got pitch data plus 0.4 and roll data is minus 0.1. So according to table equivalent pitch data number is 5 and roll data letter is D. 



Step 03: Check the fuel content with MLI Reading

To check the fuel content with MLI reading please follow the below procedure

1. Use a screwdriver to push the applicable MLI and turn it through 90 deg.

2.Hold and carefully lower the MLI fully. Then carefully lift the MLI until you feel the magnets engage

3. Read the units mark nearest to the bottom-skin of the wing and write down the number.

4. Retract the MLI and use a screwdriver to turn it through 90 deg. to lock it.

Please Note: only even number MLI units are listed in the MLI chart. To calculate the volume of fuel for uneven numbers, interpolate between the nearest even numbers in the MLI chart.


What are the data in  MLI Chart 


                            
                                                     Fig 07 MLI Chart data


Number 1 to 7 is pitch data

Letter B and F is Roll Data

Unit 2 To Max is MLI number.

Rest all number is fuel volume.


MLI Procedure flow chart

 

                          

                                               Fig 08 MLI procedure flow chart


When we do fuel quantity check with MLI please follow the flow chart and note the following points;

 1.When you start to check MLI reading always start from outboard side of wing.

 2.When you don’t get MLI reading at outboard MLI then check next inboard side MLI

Like as the procedure given in flow chart start with MLI 04 if you don’t get reading at MLI 04 move to check next inboard side MLI 03 and if you get reading at MLI 03 then refer applicable table and this would be inner cell fuel quantity. Apply the same procedure for outer cell and center tank.

3.Measure the outer cell, inner cell and center tank fuel quantity.

After calculation of all tank fuel quantity sum up all tank fuel quantity and will get total fuel quantity in volume. Multiply this total fuel quantity with fuel specific gravity and will get total fuel in kilogram.




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