Refueling a 777-300ER

[MolaKule]

Here is a simple refueling math problem:

How long does it take the ground crew (in hours) to fill the fuel tanks in a completely empty 777-300ER?

Data:

Fuel capacity - 47,890 gallons.

Ground System Fuel Pumping Rate - 318 gallons per minute (318 g.p.m.).

 

[Jdeere562]

My Iowa logic says a pinch over 2 1/2 hours.

 

[wwillson]

47,890/318/60=2.51 hours

That's a lot of fuel!!

 

[wwillson]

How did the plane have completely empty tanks? That must have been an exciting landing, unless the plane happened to run out right after landing. Either way the pilot has some explaining to do, if he isn't fired anyway.

That wasn't the question, you may be slightly over thinking.

 

[Owen Lucas]

I would think that a plane this large has at least 2 fuel nozzles (one on each wing) to fill up faster. They probably aren't ever empty unless they are brand new.

 

[Jimmy_Russells]

Can't they fill from more than one place at a time?

 

[Highlander 1459]

I would think that a plane this large has at least 2 fuel nozzles (one on each wing) to fill up faster. They probably aren't flying on empty all the time unless they are brand new.

as far as the question goes... just round it off... 300 gpm to pump 48000 gallons... 160 minutes... probably close to correct if including time to connect, ground, disconnect and such and no other issues..

I was under the impression that airlines will take on enough fuel to get where they are going.... as weight is cost... and dont necessarily fill em to the brim... maybe I am wrong but I don't think they fill em up if they don't need to...

which reminds me of the scene from Capt Ron, where he runs out of fuel and he exclaims that he cant be out of fuel because he put enough in to get to Cuba and they weren't in Cuba yet.

 

[MolaKule]

as far as the question goes... just round it off... 300 gpm to pump 48000 gallons... 160 minutes... probably close to correct if including time to connect, ground, disconnect and such and no other issues..

Why complicate matters as the question was straight forward.

I was under the impression that airlines will take on enough fuel to get where they are going.... as weight is cost... and dont necessarily fill em to the brim... maybe I am wrong but I don't think they fill em up if they don't need to...

But not part of the question.

 

[Hall]

Ground System Fuel Pumping Rate - 318 gallons per minute (318 g.p.m.).

For the mathematically challenged

Spoiler: Highly complex math conversion

318 gpm = 19080 gph

 

[MolaKule]

I would think that a plane this large has at least 2 fuel nozzles (one on each wing) to fill up faster. They probably aren't ever empty unless they are brand new.

Not part of the question, but it could have been a brand new plane or pulled out of storage for a flight.

 

[slo town]

The crazy thing to me is that's 160 tons of fuel - the weight of 80 Tesla Model 3s!

Scott

PS I think a key part of @MolaKule's question is this "How long does it take the ground crew....?" In other words the answer is not necessarily the GPM or total tank capacity. @wwillson correctly says 2.51 hours based on GPM and gallons pumped. I didn't fly airplanes for a living but there is NO WAY a plane sits for 2 1/2 hours being refueled - or 1 1/4 hours if it's half empty or needs only a partial refill. That's too much non-revenue ground time.

 

[Highlander 1459]

Why complicate matters as the question was straight forward.

But not part of the question.

question isn't super straightforward as it you still have to change hours to minutes one way or another somewhere in that question ... roundabout guess is 160 minutes.. or 2.66666666666666666666 hours... or if you want to be really anal and dont take into account any other factors like driving the fuel truck to the plane, grounding the plane, allowing it to cool off... climbing up to the fueling point and opening the fueling apparatus.... the exact answer would be 2.509958071 hours.... assuming a fill rate of 19080 gallons per hour and 47890 gallons of fuel...


funny thing is people in the know understand that jetliners take on fuel by weight...

but once again I am wandering off topic.

 

[MolaKule]

I would think that a plane this large has at least 2 fuel nozzles (one on each wing) to fill up faster. They probably aren't ever empty unless they are brand new.

Not part of the question but have you considered the internal fuel transfer pumps?

 

[Highlander 1459]

Not part of the question but have you considered the internal fuel transfer pumps?

you need to factor those internal fuel pumps in so some of us can attempt to answer the question. do you know the flow rate of the pumps in the wings?

 

[Owen Lucas]

Not part of the question but have you considered the internal fuel transfer pumps?

I have not but I presume if the limiting factor is based on external fueling rates, then 2 points of delivery would speed things up.

I have no idea about planes though. When flying with the window seat I just see some guy pull up to the plane with a giant hose reel and never see the rest.

 

[MolaKule]

question isn't super straightforward as it you still have to change hours to minutes one way or another somewhere in that question ... roundabout guess is 160 minutes.. or 2.66666666666666666666 hours... or if you want to be really anal and dont take into account any other factors like driving the fuel truck to the plane, grounding the plane, allowing it to cool off... climbing up to the fueling point and opening the fueling apparatus.... the exact answer would be 2.509958071 hours.... assuming a fill rate of 19080 gallons per hour and 47890 gallons of fuel...

It is a straight forward, simple math question.

funny thing is people in the know understand that jetliners take on fuel by weight...

but once again I am wandering off topic.

The ground pumps pump in gallon per minute. Takeoff weight does have to consider fuel weight, but that was not the qustion. Include the fuel density of the JP if you want to calculate the fuel weight per minute, another simple math exercise.

 

[MolaKule]

I have not but I presume if the limiting factor is based on external fueling rates, then 2 points of delivery would speed things up.

The external fueling rate was given.

 

[MolaKule]

you need to factor those internal fuel pumps in so some of us can attempt to answer the question. do you know the flow rate of the pumps in the wings?

I stated the question simply so the answer could be calculated simply.

 

[jhellwig]

2.509958071 Hours.

Since you are asked a question about internal pumps is the volume you stated total tank volume or usable tank volume removing the amount of empty tank space used for trimming? I don't know much about planes but I guess that number can vary based on load.

On a side thought in my world that volume is 1140 barrels of jet fuel. The smallest tank at the smallest terminal in my system that the pipeline can deliver into is around 3000 barrels (if I remember right) so just under 3 fills of that plane for that tank. I am glad my area doesn't deal with jet fuel though the line used to deliver to Offit AFB a long time ago.

 

[MolaKule]

2.509958071 Hours.

Since you are asked a question about internal pumps is the volume you stated total tank volume or usable tank volume removing the amount of empty tank space used for trimming? I don't know much about planes but I guess that number can vary based on load.

I didn't ask the question about internal transfer pumps; it came up as a side topic in post #13.

The question was based on the total tank volume for totally empty tanks, undoubtedly.