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Questions tagged [fuel-systems]

Any question regarding aircraft fuel systems, how they work etc.

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72 votes
6 answers
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Why are fuel tanks in the wings filled first, and why are they used last?

When fueling airliners, why is fuel filled first in the tanks in the wings and then the center tanks? And why do they use fuel from the center tanks first and then from the tanks in the wings? From ...
lemonincider's user avatar
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18 votes
2 answers
2k views

How is fuel managed in the Zero-G A310?

There are several Zero-G airplanes to experiment briefly microgravity without going into orbit. One is the A310 from Novespace (F-WNOV): Novespace A310 F-WNOV (source: Jonas Wirz at Airplane-Pictures....
mins's user avatar
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27 votes
4 answers
13k views

Why are the center tank pumps deactivated when slats are extended on the A320?

Why are the center tank pumps deactivated when slats are extended on the A320? I researched about this and all I can see is hints. They say it is because of regulations or certifications.
MNKY's user avatar
  • 293
16 votes
2 answers
4k views

How is fuel mass measured in airliners?

Large airliners display the amount of fuel in each tank as a mass (usually in kg or lbs) and not as a volume. This makes sense since mass is important for weight&balance considerations and the ...
Bianfable's user avatar
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57 votes
4 answers
13k views

Why do many GA aircraft not have a "Both" fuel selector?

I've been trying to rack my brain around this and asked a few CFI's who couldn't give me more than "because that is how it was done", but a good number of GA aircraft save for Cessna and maybe a few ...
Ron Beyer's user avatar
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15 votes
5 answers
7k views

What could the fuel pump failure have been that my flight experienced?

I was on an Easyjet flight (I think an A320), when mid-flight, I overheard a member of cabin crew tell another passenger there was a 'technical' issue with the aircraft, that might make us slightly ...
Cloud's user avatar
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11 votes
2 answers
1k views

What are possible explanations for fuel being expelled in this video?

In another question, I asked about whether or not a fuel spill would be reportable or not. The answer was "no", because the aircraft was not in flight. What are the possible causes of the spill ...
Steve's user avatar
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6 votes
2 answers
3k views

How does a fuel density sensor work? (densitometer, cadensicon)

While some fuel volume sensors use ultrasonic measurements this answer to How is fuel mass measured in airliners? says: The FCOM lists the sensors involved in this measurement: The FQI system ...
uhoh's user avatar
  • 5,886
6 votes
2 answers
4k views

Why does pulling the mixture to idle cutoff increase the RPM slightly?

When adjusting fuel control on a reciprocating engine, why is there a slight RPM rise (50-RPM rise) when pulling the mixture control to idle cutoff? Why if more than a 50-RPM rise, carburetor is set ...
StevenH88's user avatar
4 votes
2 answers
829 views

On what basis is the weight unit of the FQIS selected by airlines of various countries?

On what basis is the weight unit of the FQIS (Fuel Quantity Indicating System) selected by airlines of various countries? Does it depend on the local country for using imperial or metric units?
Emerson's user avatar
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90 votes
5 answers
25k views

Why do we need to starve the engine before turning it off?

This question is for Piper Tomahawk, but I guess applies to any small aircraft. Why do we need to use the fuel mixture to starve the engine before turning it off with the key? Why can't we just turn ...
Cloud's user avatar
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41 votes
6 answers
12k views

Is fuel moved around during flight on a passenger or cargo plane? If so why?

Is fuel moved around during flight on a passenger or cargo plane? If so why? Is balance an issue?
Sarah's user avatar
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31 votes
5 answers
21k views

Why didn’t the Captain of Cathay Pacific flight 780 shut down engine 1 and land with a more reasonable speed?

In the approach phase, engine 1 of Cathay Pacific flight 780 got stuck at about 70% N1 and it forced the crew to do an overspeed landing (230knots). Why didn't they shut it off by turning the fuel ...
xMooo's user avatar
  • 421
18 votes
1 answer
7k views

How does the fuel pump work in a PA-28 and when should I use it?

Just started flying again after 14 years and I'm taking this to the finish line this time. All my time, up till 10 am today, is in a C172. I did fly a PA 28-151 today and liked it. I do have some ...
user2425931's user avatar
17 votes
5 answers
6k views

Why aren't "fuel polishing" systems removing water & ice from fuel in aircraft, like in cruising yachts?

Should you sump fuel tanks when the fuel system is below freezing? the question should one sump fuel-tanks before flying, if in freezing-conditions? but this implies another question that boggles me:...
BulldozerMind's user avatar
16 votes
3 answers
12k views

Is excess fuel leaking normal during take off of a B737?

When we look over this video it's noted that some fuel is coming off from the left wing during the rotate. This is the position of the fuel vent within the wing, ...
Germano Sarmento's user avatar
13 votes
5 answers
11k views

Why is mixture lean recommended on the ground?

Mixture lean is typically recommended during the ground operations at sea-level pressure in the POHs of most small aircraft equipped with a carburetor system. Why is it? I heard some people saying it'...
lemonincider's user avatar
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10 votes
1 answer
4k views

Why would the outer tanks fuel on the A320 be colder than the inner tanks?

I have noticed in a number of instances during long flights typically over 5 hours the fuel in the outer tanks on the A320 are colder than the fuel in the inner tanks. This goes against the system ...
Jai's user avatar
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9 votes
1 answer
3k views

Why does fuel vaporize in the carburetor?

So I get that a carb vaporizes fuel and mixes it with the air intake for the engine. But my question is what is the explanation for what causes the fuel to vaporize after it exits the fuel nozzle?
BDeFreitas's user avatar
8 votes
1 answer
386 views

Can IPA be used as a FSII with MoGas, particularly with a Peterson STC?

This question established a basis for the use of 100% Isopropyl Alcohol (IPA) as a Fuel System Icing Inhibitor (FSII) in aviation gasoline systems. However, this Cessna Service Letter documents that ...
J W's user avatar
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7 votes
1 answer
631 views

Can you safely operate a 777 with diesel?

Is it possible to safely operate a Boeing 777 on diesel instead of Jet-A? Are there any regulations that prevent this? Would it cause any damage?
TayE's user avatar
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4 votes
2 answers
4k views

Where is the APU fuel pump on the A320?

I'm looking for APU fuel pump location for A320 aircraft series. I'll be much appreciated if you provide a link to some images, schemes.
Victor Chernobay's user avatar
3 votes
1 answer
209 views

How long can a turbine-engined aircraft be left fuelled?

Presumably, if one is going to be keeping an aircraft on the ground for a long time without running the engines or the APU, the aircraft's fuel tanks will need to be drained and purged... ...to ...
Vikki's user avatar
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1 vote
2 answers
14k views

Why does the cabin air sometimes smell of kerosene? [duplicate]

Why does the cabin air sometimes smell of jet fuel, although bleed air is tapped before it comes in contact with fuel ? How is this possible? I have smelled this a couple of times in my life (twice ...
summerrain's user avatar
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