A twin-engine turbine helicopter has two side tanks with a capacity of 250 litres each and a centre tank with a capacity of 600 litres. A fuel pump ensures that the side tanks are fed from the centre tank at a rate that they are always full. Fuel consumption is 125 litres/h per engine.
You depart with 700 litres of fuel on board. 35 minutes into the flight, the fuel pump feeding the side tanks from the centre tank fails. What is the helicopter's endurance?
The question states that the fuel pump ensures that side tanks are full at all times.
Therefore, when the fuel pump fails during flight, we can assume that the side tanks will be full with 250 litres each, thus 500 litres both side tanks.
With fuel flow of 125 litres/h per engine, thus 250 litres/hr both engines, and 500 litres both side tanks, the endurance will be:
- 500 litres / 250 = 2 hours.
Additional information for better comprehension:
We depart with 700 litres on board, so the initial fuel distribution is:
- 250 litres in each side tank (500 litres both side tanks)
- 200 litres in the centre tank.
After 35 min of flight, the aircraft will have burnt:
- 250 l/h x 35 min = 146 litres
So, in the centre tank will remain:
- 200 litres - 146 litres = 54 litres of fuel.
Your Notes (not visible to others)
This question has appeared on the real examination, you can find the related countries below.
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Pakistan1
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United Kingdom1
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