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PPL Video Lectures (10 Jul 2020)

PPL Video Lectures covering Aerodynamics, General Knowledge, Performance, Meteorology And Navigation are now available through our website see front page for details.

× Welcome to the CPL Performance question and answer forum. Please feel free to post your questions but more importantly also suggest answers for your forum colleagues. Bob himself or one of the other tutors will get to your question as soon as we can.

Loading exam Q10 - Online Performance Course

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lucasgozzard created the topic: Loading exam Q10 - Online Performance Course

Hi Bob,

I've just sat the Loading exam for the Online Performance Course. However, I'm unsure as to how you've arrived at the answer to the attached question.

The steps I used were:
1. Calculated flight fuel required - 54 gal
2. Calculated MTOW - most limiting was 2650kg
3. Used flow chart - MTOW 2650kg; Fuel at T/O 302kg; ZFW 2348kg; Pilot+BEW 2076kg

So wouldn't the max payload be 2348-2076 = 272kg?

Hope you can help.

Lucas.
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bobtait replied the topic: Loading exam Q10 - Online Performance Course

Can you show me how you got 302kg for total fuel at take-off
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lucasgozzard replied the topic: Loading exam Q10 - Online Performance Course

Sure Bob.

So I calculated flight fuel to be 54 gal. So total fuel at t/o = 54 x 1.15 + FR (.75 x 28 GPH fuel flow) + 60 mins holding (28 gal) = 111 gal = 302kg.
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Stuart Tait replied the topic: Loading exam Q10 - Online Performance Course

G'day Lucas

Your fuel flows are too high (The cruise is to be at 65% MCP with a TAS of 185 kt) ie: 14 gph


(Note that the fixed reserve for a charter flight is based on 45 min at 20 gph, i.e. 15 gal. It is
normal in large aircraft to carry the 45 min fxed reserve at a "holding rate". After all, it is intended for use if the aircraft arrives and for some reason cannot land immediately)


and you have to calculate your variable reserve at 10 % (Since Nov 8th)

Don't forget Taxi allowance 3 gal

Cheers
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lucasgozzard replied the topic: Loading exam Q10 - Online Performance Course

Hi Stuart,

14GPH is the fuel flow for one engine at 65% power so two engines would be be 28GPH.

Ok so fixed reserve will be always 15 gal then? That's now reduced to 30 mins yes? Have these qns been updated to reflect the new fuel requirements?

For the max cargo/fuel flowchart, the box below MTOW says fuel at takeoff so I didn't allow for the taxi of 3 gal.
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Stuart Tait replied the topic: Loading exam Q10 - Online Performance Course

Only Private ops are 30 min fixed reserve

Your right about taxi

I'm working through any questions that have been missed in the update I think this is one of them

I'll work it through and see what I come up with
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lucasgozzard replied the topic: Loading exam Q10 - Online Performance Course

Ok thanks Stuart.

Let me know how you go.

Cheers.

Lucas.
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Stuart Tait replied the topic: Loading exam Q10 - Online Performance Course

G'day Lucas

I got 325 kg and I will have to change the answer to reflect that

Cheers
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lucasgozzard replied the topic: Loading exam Q10 - Online Performance Course

Ok thanks Stuart. I'll re-work the qn again also to ensure I get the same answer.

Cheers.

Lucas.
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lucasgozzard replied the topic: Loading exam Q10 - Online Performance Course

Hi Stuart,

I got 316kg now lol. Are you able to explain how you arrived at 325kg? My figures are below:

Flight fuel = 54 gal (116mins x 28GPH)
Var Rsv = 10%
Fixed Rsv = 15 gal
Holding fuel = 20.4 gal (given that holding fuel is at 45% MCP i.e fuel flow of 20.4 GPH)

Therefore, takeoff fuel is 95 gal = 258kg.

Lucas.
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