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Excercise 4.18 - Question 7

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(@user4996)
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Hi,
I believe the working-out answer for Exercise 4.18 Question 7 (Answer on page 129) has a typo.
Note: The actual answer is correct, however the "Burn 6 gal at 17.2 gph = 31 min" should read "Burn [b]9[/b] gal at 17.2 gph = 31 min"
[attachment=1457]ex418-7ans.png[/attachment]
Cheers
SJM



   
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User 3940
(@user3940)
Honorable Member Customer
Joined: 16 hours ago
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G'day SJM

Thanks for that we really appreciate the feedback helps no end

Cheers



   
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(@user4996)
Trusted Member Customer
Joined: 16 hours ago
Posts: 43
Topic starter  

No problems 🙂
If only I could shift my level of attention to detail to the actual exam!



   
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(@user5486)
Eminent Member Customer
Joined: 16 hours ago
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Hi Guys,
A little confused by this question as there seems to be no allowance for Variable reserve fuel. Are we assuming to use the variable fuel while holding given the unexpected wheels up landing?

Thanks
Shaun



   
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(@user4996)
Trusted Member Customer
Joined: 16 hours ago
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Topic starter  

Hi Shaun,
Under the regulations, variable fuel is only required from origin to destination (but not to the alternate) - and that too for charter and not necessarily private operations.

Fixed reserves are 15 gallons for all operations (per the company policy in the Echo supplement)

In this question, you arrive overhead the destination with 50 gal on-board (we don't really know if variable was used or even required for this flight - it doesn't matter). However we assume the fixed reserve is intact (since the question doesn't comment on it).

So 50 gallons overhead the destination, less 15 gal (fixed reserves) = 35 gal remaining for safe endurance purposes overhead the destination.

Of the 35 gal, 26 gal is required to get you to the alternate aerodrome (remember alternate doesn't require variable), leaving 9 gal of margin that you can use for holding over the destination (in the hope the wheels up is cleared away in that time :-))

9 gal at 17.6 gph (35% MCP for holding per the echo manual) = 31 minutes of holding over the destination before you must divert.
If you arrived at the destination at 0412 UTC, you can hold for 31 min and at 0443 UTC you must begin your diversion to the alternate, where all going well you arrive with exactly 15 gallons of fixed reserves remaining.



   
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(@user5486)
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Joined: 16 hours ago
Posts: 14
 

Thanks SJM, a case of over complicating the question for myself. I assumed there should be VR but given the information in the question it is not really feasible to calculate VR. Thanks for your explanation



   
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