Fuel Consumption questions?

[34486 0]

Hello, just some questions on what affect fuel consumption with engines and apu:

On which planes these apply too, if any or if all:

Does anti ice create more of a load and require more fuel?

Does electrical load, such as turning on more lights ect create more of a load and require more fuel?

Do hydraulic pumps (engine driven) create more of a load and require to burn more fuel?

 

Just wondering.

 

~Ag (Will) W. Si

[JRBarrett 3,076]

53 minutes ago, 34486 said:

Hello, just some questions on what affect fuel consumption with engines and apu:

On which planes these apply too, if any or if all:

Does anti ice create more of a load and require more fuel?

Does electrical load, such as turning on more lights ect create more of a load and require more fuel?

Do hydraulic pumps (engine driven) create more of a load and require to burn more fuel?

 

Just wondering.

 

~Ag (Will) W. Si

Engine generators and hydraulic pumps don’t have any significant effect. The hydraulic load is minimal most of the time - it is at a maximum mainly during gear retraction and extension and when flaps and slats are in motion. Those events are of limited duration.

Likewise the load presented by the generators is relatively constant once all aircraft systems are online after engine start.

Anti-ice can definitely have an effect - especially wing anti-ice, which on most aircraft is the single biggest consumer of engine bleed air when it is in operation. When wing anti-ice is brought online, engine N1 speed will decrease, requiring an corresponding increase in engine thrust lever position (and fuel flow) to prevent a loss in airspeed. On most Boeing aircraft, the descent forecast page in the FMS includes a field where the pilot can enter the altitude where it is estimated that wing anti-ice may first be required, so that the FMS can factor that into its engine performance calculations. An aircraft will typically spend more time in icing conditions during the descent and approach phase than it will during climb, which is why the estimated anti-ice “on” entry is found on the FMS descent forecast page.

Cowl anti-ice has some impact, but much less than wing anti-ice.

 

[34486 0]

Oh, alright! thanks! I am so amazed at how much PMDG does with Boeing to make these aircraft as realistic as possible! I probably should have decided to check the engine display, and I just did now and I even see fuel flow change as I turn off bleed air on 2 or 1 on the 777-200lr. Amazing!

 

~Ag (Will) W. Si