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Question ID:330276

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  • Question ID:330276

    A flight has to be made with the single engine sample aeroplane. For the fuel calculation allow 10 lbs fuel for start up and taxi, 3 minutes and 10 lbs of additional fuel to allow for the climb, 10 minutes and no fuel correction for the descent.
    Planned flight time (overhead to overhead) is 03 hours and 12 minutes.
    Reserve fuel 30% of the trip fuel.
    Power setting is 23 in.HG (or full throttle), 2300 RPM, 20°C lean.
    Flight level is 70 and OAT is ISA + 20°C.
    The minimum block fuel is:


    The correct answer is 325 lbs because Sector time= (Climb adjustment) 3mins + 3hrs 12mins + (descent adjustment) 10 = 3hrs 25mins, or 3.417hrs Fuel flow at cruise(7000ft, ISA +20°C 2300RPM) ???????? = (69 + 68.5) / 2 = 68.75 PPH Sector fuel= (climb adjustment) 6 + (3.417 x 68.75) + (descent adjustment) 0 = 6 + 235 + 0 = 241 lbs Ramp fuel= TAXY + TRIP + RESERVE (30% of TRIP) ????... = 10 + 241 + [(30/100) x 241] = 323 lbs

    I can get why some questions take in account contingency fuel and others not. The theory for performance B aircraft says that the minimum ramp fuel must include contingency fuel so why this question doesn't ???? Is there a generic rule that I can follow in order to understand when a question is asking to account for cont. fuel and when not please?

  • #2
    Re: Question ID:330276

    I understand your confusion - in this question they have told us that 'RESERVE FUEL' is 30% of TRIP FUEL. When they give this general 'RESERVE' wording, I would assume that by RESERVE they mean all reserves, or the sum of:

    (i) contingency fuel; and
    (ii) alternate fuel, if a destination alternate aerodrome is required; and
    (iii) final reserve fuel; and
    (iv) additional fuel, if required by the type of operation (e.g. ETOPS);

    This should keep you straight on the questions!!

    Tom

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    • #3
      Re: Question ID:330276

      thank you so much tom. Fortunately you're a such good teacher otherwise FP would be a nightmare of exam!

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      • #4
        Re: Question ID:330276

        Im sorry but I still don't understand this question.

        Start up/ taxi = 10lbs
        Climb = 10lbs
        Trip = (3.2H x 68.75) 220lbs
        Reserve = (220+10) x 0.3 69lbs

        It all adds up to 309 lbs

        I don't get it
        Last edited by Rob_20; 22-10-2014, 22:03.

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        • #5
          Re: Question ID:330276

          These questions can be a little confusing - for this one the allowance for CLIMB includes both additional TIME and FUEL, the allowance for descent only includes a TIME allowance.

          Sector time = TRIP TIME (overhead to overhead) + CLIMB allowance + DESCENT allowance
          Sector time = (Climb adjustment) 3min + 3h 12min + (descent adjustment) 10min = 3h 25min, or 3.417h

          From the SEP cruise tables (CAP 697 Section 2 page 4:
          Fuel flow at cruise(7000ft, ISA +20°C 2300RPM) = (69 + 68.5) / 2 = 68.75 PPH

          Sector fuel= (climb adjustment) 6 + (3.417 x 68.75) + (descent adjustment) 0 = 6 + 235 + 0 = 241 lb
          Ramp fuel= TAXY + TRIP + RESERVE (30% of TRIP) = 10 + 241 + [(30/100) x 241] = 323 lb

          Tom

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          • #6
            Sorry for the revival of an old thread but surely the calculated answer and method is incorrect.

            The question states that the additional fuel for climb (other than 10 minutes) is 10lbs..... but the answer and explanation only add in a further 6lbs.....

            Not sure if i am missing something here or if its wrong. Either way the answers are close enough to get the right one!

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