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Questions tagged [fuel-systems]

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

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83
votes
4answers
17k 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 ...
71
votes
6answers
22k views

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 ...
53
votes
8answers
26k views

Why are fuel tanks located in wings?

Passenger aircraft have fuel tanks in the wings. Why? What are the advantages and disadvantages of this location ? examples of disadvantages I would suspect: added weight increases the structural ...
47
votes
1answer
6k 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 ...
40
votes
6answers
11k 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?
27
votes
4answers
15k 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 ...
23
votes
6answers
4k views

Is there a tank priority sequence for using the fuel tanks?

Is there a tank priority sequence for using the fuel tanks, or does the pilot decide?
23
votes
2answers
7k 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.
18
votes
2answers
1k 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....
16
votes
3answers
8k 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, ...
16
votes
1answer
3k views

Why is fuel used as a hydraulic fluid?

Why is fuel used in some servo-systems as a hydraulic fluid (fueldraulic systems) of modern civil and military aircraft such as the Boeing 777-200/-300 (Pratt & Whitney PW4084) or the Lockheed ...
15
votes
4answers
5k 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 ...
15
votes
3answers
2k views

What is the appropriate fuel tank selection to land a 172?

On a recent checkout on a C172 I was told to select "fullest tank" as opposed to "both" that I have been doing for years. Given the aircraft is high wing (gravity feed) with no auxiliary fuel pump ...
14
votes
4answers
4k views

What is the purpose of the fuel shutoff valve?

Most GA planes have a fuel shutoff valve which I don't quite understand the purpose of. Does it cut the fuel flow with the mixture. My theory is to prevent fuel flow at earlier stage for safety ...
12
votes
5answers
5k 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'...
12
votes
2answers
2k views

Why fuel left/right when C172 is secured?

The C172 POH checklists say to set the fuel selector to "right" or "left" when securing the plane but "both" while operating the plane. What is the point of changing the fuel selector when the engine ...
11
votes
1answer
378 views

How do fuel trim and air bubbles prevention work in inverted flight?

I was reading Why do many GA aircraft not have a "Both" fuel selector? and voretaq7's excellent answer got me to thinking. He cites the regulations noting that the plane must only draw fuel from one ...
10
votes
1answer
488 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 ...
9
votes
4answers
2k views

Is there any work on improving fuel tanks so they could store hydrogen?

I think that hydrogen is among the best fuels for use in supersonic and hypersonic flight, is there any work on improving fuel tanks so they could store hydrogen? What would be the best state to ...
9
votes
4answers
2k views

How do you know which fuel an aircraft uses?

Other than the decals on the plane, how would you know what fuel to use in an aircraft? Where is this limitation documented? For some aircraft, does this limitation include some sort of substitute ...
9
votes
1answer
506 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 ...
8
votes
1answer
241 views

Why was the Graf Zeppelin's endurance when fully fuelled with both fuels less than the sum of its endurances with each fuel separately?

The LZ-127 Graf Zeppelin used a unique dual-fuel system, with both a gasoline tank and a set of gas cells filled with blau gas; the airship could be flown using either fuel or both. The purpose of ...
8
votes
1answer
298 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 ...
7
votes
1answer
2k views

How does the FAA define fuel capacity for ultralights?

Ultralights under FAR 103 are regulated to a capacity of 5 gallons. I'm wondering how exactly fuel capacity is defined, does it include fuel in the lines, and in the carburetor bowl or elsewhere or ...
7
votes
1answer
2k views

What is the freezing point of 100LL Avgas?

Does anyone knows the exact freezing point of Avgas (100LL) ? I found that Jet A-1 freezes at −47 °C / −53 °F (wikipedia), but didn't manage to find any info on Avgas.
7
votes
1answer
493 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?
7
votes
1answer
1k views

Why not leave an electric fuel pump on all the time?

This question is related to single-engined piston airplanes equipped with an electric fuel pump like the Piper Dakota/Arrow etc. The POH states that the fuel pump should be switched on for takeoffs/...
6
votes
4answers
588 views

Why is alcoholic gasoline such a showstopper for aviation?

One of the main reasons the common avgas grades are still full of 3-plumba-3,3-diethylpentane is the incompatibility of many aircraft fuel systems with the oxygenates (primarily ethanol, with some ...
6
votes
1answer
608 views

Does the mixture and throttle setting affect the quality of priming of fuel prior to start?

This question is a generality. For airplanes with small reciprocating engines, does the mixture and throttle setting at the time of priming affect the quality of the priming or the engine start, or ...
6
votes
1answer
291 views

Has fuel boiling ever been an issue for high altitude aircraft?

Are special measures being taken to prevent fuel from boiling inside the fuel systems at high altitudes? If so, when (with what aircraft) did this practice start? (question is pertaining to air-...
6
votes
1answer
273 views

How is that there is no leak through the fuel vents during aerobatics maneuvers?

Can anyone tell me how aircraft such as jet fighters and stunt planes design the fuel tank vent system to prevent fuel leaking through the vents when performing aerobatics, 360 flips and complex ...
6
votes
1answer
293 views

Where is fuel metered in continuous flow fuel injection system?

How is fuel metered in continuous flow fuel injection system?
5
votes
3answers
356 views

What causes fuel gauges to be untrustworthy?

I went on my first flight yesterday (Cessna 152), and I was told not to trust the fuel gauges and to check fuel levels manually. The instructor said that the only fuel gauge reading that I can trust ...
5
votes
2answers
3k views

Why does fuel vaporization in a carburetor cause a temperature decrease rather than a rise?

So I know the most "prominent" conditions of carburetor icing is anywhere from 20 to 70 °F with visible moisture. There is also a tendency to have icing in the carburetor in the venturi throat due to ...
5
votes
2answers
251 views

Could hydrazine be used as a scramjet propellant?

Hydrazine is used a monopropellant in Satellite OMS rockets. But interestingly enough, it's highly exothermic decomposition into ammonia, nitrogen, and hydrogen provides heat for an endothermic ...
5
votes
1answer
2k views

Where is the fuel vent on a Piper Archer TX?

I realized I haven't really noticed where the fuel vent is for the 2016 Piper Archer TX that I've flown, but I assume the fuel is vented from the fuel cap. Is that correct?
4
votes
2answers
636 views

Do Diesel engines have a mixture option?

Consider the DA-42, it has no mixture control. Is that because it is run on Jet-A/diesel? Or is the mixture control automated?
4
votes
1answer
849 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.
4
votes
1answer
931 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?
4
votes
1answer
308 views

In normal condition, is the Airbus A320 APU fuel supplied by the main engine boost pump only?

I have a question relating to APU fuel system. As said in material, there are 2 system supplying fuel for APU to operate. 1st one is primary and 2nd one is secondary. In the 1st system or low ...
4
votes
1answer
457 views

Why do the A320's centre tank pumps stop working 5 minutes after the low level has been reached?

I'm new here and I'm in training course for Airbus A320. In the training material, it's said that the centre tank pumps are controlled to stop automatically 5 mins after the low level fuel has been ...
4
votes
0answers
191 views

Is there an indication in the cockpit when the refueling control panel door is open on the ATR72?

Is there any indication (light, MFD/SD displays) in the cockpit of opened/closed refueling control panel door in ATR72-600?
3
votes
3answers
2k views

Are there any 100% renewable energy aircraft in development?

There seem to be several options for aircraft R&D regarding cleaner fuels for the time when fossil fuels are no longer economically viable. Some of these include: Algae. A drop-in fuel. These ...
3
votes
2answers
1k views

Was there ever a fuel-injected Spitfire?

I couldn't find one but did it ever exist? Would adding fuel injection have improved combat effectiveness or fuel efficiency?
3
votes
1answer
115 views

Is fuel in trim tank usable?

Some aircraft (A380, Concorde,...) are equipped with a trim tank in the tail. Transferring fuel from or to this tank help controlling the CG. This feature can only be achieved if there is fuel to ...
3
votes
1answer
525 views

What happens to the control systems of a BAe 146 when the aircraft runs out of fuel?

On a BAe 146, is there any way to control the aircraft when it's out of fuel? Does the APU run on a separate tank? Can the engines be windmilled for power generation?
3
votes
1answer
511 views

Do Airbus aircraft fitted with ACT have additional fuel system controls?

Do Airbus aircraft fitted with ACT (Additional Center Tank) have a push button that controls the fuel transfer to the main center tank? If yes, where is it located?
3
votes
2answers
335 views

How are fuel tanks tested and certified?

What ground tests are carried out for testing and certifying wing fuel tanks for use in passenger aircraft? Is there any chamber to simulate flight conditions? If so, how is the chamber constructed?
3
votes
1answer
1k views

How does this fuel pump work?

This question is about the fuel pump controlled by the hydro-mechanical fuel control unit. This is part of a fuel system for a turboprop engine, described on this page which actually comes from a ...
3
votes
1answer
347 views

What are the dimensions of an NPT pipe for fuel systems?

I have a question about NPT (National Pipe Thread) tapered connectors that are used in fuel systems of several airplanes. Please take a look at this standard-wall one-side threaded nipple (3/4 pipe ...