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NoahBryant

Fuel Management

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Can someone help me understand the diagram on page 67?

I am trying to understand the goal of making the tank changes. For example, it says that you should switch from mains to alternates about 20 mins after takeoff. Then at some point, you switch 2 and 3 back on main. How do I know when that point is? Same thing for the rest of the changes. 

I have read through the section on why you should do this correctly, but I can't for the life of me figure out what fuel management goals I need to shoot for throughout the flight. Especially since I will rarely ever do a full fuel flight. 

  • Upvote 1

Noah Bryant
 

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I re-read this section today, so I'm slightly informed. So, I'll try.

1st, the diagram (figure 20) on page 57 is missing some red on some lines. This makes it confusing. Same thing with figure 21 on page 58, but only on the top example. The crossfeed lines are not red even though they are active.

With that out of the way, if you're flying longer flights, you'll want to adjust fuel feeds. Normally, it shouldn't be necessary to use crossfeed. See the paragraph on page 57 Normal and Cross-Ship Fuel Cross-Feed Operation.

On long to moderate flights, you'll need to use up the Alternate tank fuel. To use up the fuel in the alternate tanks, simply move the fuel select lever to Alt On and monitor the fuel gauge to determine when to switch back to the mains. Turn on the fuel pumps to low when switching.

Happy flying.


Richard Chafey

 

i7-8700K @4.9GHz - 32Gb @3200  - ASUS ROG Maximus X Hero - EVGA GTX1080Ti - CH Fighterstick - CH Pro Throttle CH Rudder pedals

P3D, X-Plane 11

 

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If you are using the AFE, don't run your mains dry in flight, because the AFE will switch to mains on approach even if they are empty!

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5 minutes ago, petesmiffy said:

If you are using the AFE, don't run your mains dry in flight, because the AFE will switch to mains on approach even if they are empty!

Welcome to the forum. Please note that full names - first and last - are required in your posts here.

As far as the MAINS / ALTs goes, this is correct. You should burn out of the ALTs before burning out of the mains (at cruise), not only to mesh with the AFE's checklists, but also in practice.


Kyle Rodgers

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Thanks, all - That helps me a lot. I am doing my best not to use AFE at all but still need him for takeoff.

So to be clear, 

  • Mains during climb
  • Once leveled out and everything is stable, switch to alternate dry
  • Switch back to mains 
  • ??? I am assuming I should use crossfeeds to get the quantities in each tank equal?

 


Noah Bryant
 

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1 hour ago, NoahBryant said:
  • Mains during climb
  • Once leveled out and everything is stable, switch to alternate dry
  • Switch back to mains 
  • ??? I am assuming I should use crossfeeds to get the quantities in each tank equal?

Yep.

My flow is:

  • T/O and Climb: Mains
  • Cruise: 1-2 and 3-4 crossfeeds on, and tank selectors and boost pumps (low) to fuller ALT tanks (other tanks OFF), until equal...then tank selectors all to ALT, crossfeeds off, pumps off
  • Later Cruise: (leaving a hundred or so in the ALTs) Back to Mains, crossfeeds on, and tank selectors and boost pumps (low) to fuller Main tains (other tanks OFF), until equal...then tank selectors all to ALT, crossfeeds off, pumps off
  • Descent: same as cruise
  • Approach: if not already tank/eng, set up tank to eng
  • Landing: same
  • Upvote 4

Kyle Rodgers

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15 minutes ago, scandinavian13 said:

Yep.

My flow is:

  • T/O and Climb: Mains
  • Cruise: 1-2 and 3-4 crossfeeds on, and tank selectors and boost pumps (low) to fuller ALT tanks (other tanks OFF), until equal...then tank selectors all to ALT, crossfeeds off, pumps off
  • Later Cruise: (leaving a hundred or so in the ALTs) Back to Mains, crossfeeds on, and tank selectors and boost pumps (low) to fuller Main tains (other tanks OFF), until equal...then tank selectors all to ALT, crossfeeds off, pumps off
  • Descent: same as cruise
  • Approach: if not already tank/eng, set up tank to eng
  • Landing: same

Interesting.. not what is on the diagram and somewhat more complex.  The POH method works too.


Dan Downs KCRP

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Yep, which is why I definitely added the 'my' to my earlier post to note that it's different.


Kyle Rodgers

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1 hour ago, scandinavian13 said:

Yep.

My flow is:

...

 

Thanks, Kyle that's exactly what I was looking for and makes sense. 

59 minutes ago, downscc said:

Interesting.. not what is on the diagram and somewhat more complex.  The POH method works too.

I'm still not sure where in the POH this is explained. It does a great job of explaining how to do things, just not when. 


Noah Bryant
 

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Noah, superb thread you started because I am just about to install this aircraft later tonight, and this thread is informative on top of the Tutorial I will have to master first.


Rick Almeida

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5 minutes ago, vc10man said:

Noah, superb thread you started because I am just about to install this aircraft later tonight, and this thread is informative on top of the Tutorial I will have to master first.

Tutorial 3 will have a bit more on it, but I'm waiting on a few other things to fall into place before I kick that out the door.

  • Upvote 1

Kyle Rodgers

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11 minutes ago, scandinavian13 said:

Tutorial 3 will have a bit more on it, but I'm waiting on a few other things to fall into place before I kick that out the door.

Good to know, Kyle. Thanks. Look forward to that.

As a kid, I used to watch the DC-3, -6, and -7 landing and take off from Eastleigh airport,(replaced today by HKJK)


Rick Almeida

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Kyle, I like your flow and guess I'll adapt it, too. Thanks for sharing!


Regards.
Matthias Hanel
 

MilViz Beta Team // Econair Staff

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2 hours ago, NoahBryant said:

I'm still not sure where in the POH this is explained. It does a great job of explaining how to do things, just not when. 

POH pg 56, basically in this scheme you change configuration before a tank is empty.  Column numbers refer to the figure on pg 56:

Climb on Mains (Col 1) then switch to AUX tanks (Col2)

Cruise on AUX until inboard AUX are low (I go down to 100-200 lbs) then switch ENG 1 & 2 to Mains, outboard ENG remain on AUX (Col 3)

When outboard AUX are low then switch on XFEED 1&2, 3&4 such that each pair on a side is fed from that sides inboard MAIN (Col 4)

When inboard MAIN are same level as outboard MAIN set up each main tank to each respectful engine (col 5).

This method is easier for me to grasp and follow without have the book open in front of me.


Dan Downs KCRP

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