5 / 20

A transport helicopter with a tank capacity of 2 532 litres at a fuel density of 0.79 kg/l is to operate a flight carrying the maximum possible fuel load. Given the following information, the maximum permissible Take-Off Fuel load for this flight is:

Performance limited take-off mass (MTOM): 8 240 kg
Performance limited landing mass (MLM): 8 500 kg
Dry Operating Mass (DOM): 5420 kg
Traffic Load (TL): 680 kg
Trip Fuel: 1 005 kg
Contingency and Final Reserve Fuel: 180 kg
Alternate Fuel: 460 kg
Additional Fuel: 200 kg

  • A
    2 140 kg
  • B
    1 550 kg
  • C
    1 845 kg
  • D
    2 000 kg

Refer to figures.
Dry Operating Mass (DOM) is the total mass of the helicopter ready for a specific type of operation excluding all usable fuel and traffic load.

Convert fuel tank capacity from volume to mass by:

  1. Fuel mass = Fuel volume x Specific Gravity = 2 532 litres x 0.79 = 2 000 kg

The question is asking for the Maximum permissible Take-Off Fuel (TOF). In order to calculate the TOF the block fuel is necessary to be known.

Block fuel is the total fuel onboard for the flight:

  1. TOF = trip + contingency & final reserve + alternate + additional fuel
  2. TOF = 1 005 kg + 180 kg + 460 kg + 200 kg= 1 845 kg

Calculate the underload for performance limiting take-off mass by:

  1. Underload = MTOM - DOM - TOF - TL
  2. Underload = 8 240 kg - 5 420 kg - 1 845 kg - 680 kg = 295 kg

Calculate the underload (the difference between actual mass and limit mass) for performance limiting landing mass by:

Landing Fuel (LF) = TOF - Trip fuel = 1 845 kg - 1 005 kg = 840 kg

  1. Underload = MLM - DOM - LF - TL
  2. Underload = 8 500 kg - 5 420 kg - 840 kg - 680 kg = 1 560 kg

Knowing that we have 295 kg from the all up weight for the performance limiting take off mass and 1 560 kg from the performance limiting landing mass. The most limiting mass is for take off. Therefore, maximum permissible take off fuel can be derived by taking the fuel onboard and adding the underload:

  1. Total fuel at MTOM = 1 845 kg + 295 kg = 2 140 kg
  2. Total fuel at MLM = 680 kg + 1 560 kg = 2 240 kg

The fuel tank capacity (2 000 kg) is more limiting than both the above answers. Therefore, the correct answer is 2 000 kg.

NOTE:
For this type of questions, it’s advised to make a table with the different masses. Thus, giving a visual and simplified way of solving the question.

Your Notes (not visible to others)



This question has appeared on the real examination, you can find the related countries below.

Keyboard Shortcut Use Keyboard Shortcuts