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Maximum Holding Time

  • simsim
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simsim created the topic: Maximum Holding Time

Hi All,

Just one question, just want to know if my working out is correct.

Given:

Flight fuel: 190L
Fixed: 60 L
Variaible: 15%
Startup and taxi: 12L
Holding fuel flow: 45L

What is max. holding time for the aircraft if it was loaded with 350 Liters of fuel at start up.

Avialble answers are
A. 80 Min
B. 133 Min
C. 60 Min
D. 90 Min


My work out:

1. 350/1.15=304L
2. 304-190-60-12=42L
3. 42 L in tank @ 45 L p/h = 56 min


Look forward to all your feed back.
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  • simsim
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simsim replied the topic: Re: Maximum Holding Time

Sorry guys, this was supposed to be in CPL Performance. Not sure how it got to General Enquiries
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Richard replied the topic: Re: Maximum Holding Time

Hi Simsim,

No you've not quite got it there. If you look at your working your first step is to remove a 15% reserve off your total fuel on board. (350 / 1.15). You actually only apply the 15% variable reserve to your flight fuel. You don't need to apply a variable reserve on your fixed reserve, taxi and start-up or holding fuel.

So, the steps to process the question are:

First subtract Taxi& Start-up since we are given total fuel at start-up:
350 - 12 = 338

Now subtract the fixed reserve:
338 - 60 = 278

The variable reserve is only applied to flight fuel so that amount will be:
(190 x 1.15) = 218.5

Let's take that away from our subtotal now:
278 - 218.5 = 59.5

That's what's left for holding. Holding at 45 lph with 59 litres is:
59.5 / 45 * 60 = 79.3 or about 80 minutes.


Cheers,

Rich


EDIT: Topic moved to CPL-Performance ;)
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