Hi Bob,
I'm unsure as to how the answer is 51 minutes in the attached question. Are you able to explain?
My methodology was as follows:
1. Calculate flight fuel (Total distance x Fuel Flow/GS) = 500 x 28/180 = 78 gal
2. Calculate minimum fuel reqd with that flight fuel required = 78 x 1.15 + 15 + 3 = 108 gal
3. Actual fuel on board at startup = 125 gal. So, 125 - 108 = 17 gal margin
4. Maximum holding time = 17 / 17.2 = 59 mins
Lucas. [attachment=1435]Capture.PNG[/attachment]
The new CAAP has come into effect meaning 45 mins at 10% which changes things a little too
It looks like they used the 28GPH fuel flow to get the 51 mins. I get around 87 too
Hey mate,
Yeah I wasn't sure if the questions had been updated with new requirements. Stuart is still working through it. Not sure why they used 28 GPH for the holding as the supplement says holding is at 35% power?
I can see nothing wrong with your working. 59mins is correct. I guess you would still have to choose 51mins since it is the only answer given that is correct. Also, if you use the new 10% variable reserve requirement, the answer comes out to 74 minutes which would still make 51mins the only choice.
Thanks Bob!
Unless the question stipulates a certain power setting for holding for the Echo, do we refer to the Echo datasheet where it says holding power is at 35%?
Cheers.
Lucas.
No. The Echo data I have given will not be available in the exam. However, the examiner will have to give you any power settings and fuel flows with respect to holding. Also, you won't have to look up TAS tables or fue flow tables - all of that sort of information will be given in the text of each question.
Bob
Ok great. Thanks for clarifying Bob!
Cheers.
Lucas.
