What the purpose of the fuel shutoff valve?Why do many GA aircraft not have a “Both” fuel selector?How does this fuel pump work?Why does fuel vaporization in a carburetor cause a temperature decrease rather than a rise?Why is mixture lean recommended on the ground?What is the relationship between fuel mixture and RPM in a reciprocating engine?Why not leave an electric fuel pump on all the time?How is that there is no leak through the fuel vents during aerobatics maneuvers?Why doesn't the Convair 580 have check valves to prevent inadvertent fuel transfer?How do you lean mixture using only the instruments on a C172 Skyhawk?Are there design guidelines for sizing vent/surge tanks?
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What the purpose of the fuel shutoff valve?
Why do many GA aircraft not have a “Both” fuel selector?How does this fuel pump work?Why does fuel vaporization in a carburetor cause a temperature decrease rather than a rise?Why is mixture lean recommended on the ground?What is the relationship between fuel mixture and RPM in a reciprocating engine?Why not leave an electric fuel pump on all the time?How is that there is no leak through the fuel vents during aerobatics maneuvers?Why doesn't the Convair 580 have check valves to prevent inadvertent fuel transfer?How do you lean mixture using only the instruments on a C172 Skyhawk?Are there design guidelines for sizing vent/surge tanks?
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$begingroup$
Most GA planes have fuel shutoff vavle wich I don't quite understand the purpose of it if you can cutt the fuel flow with the mixture.
my theory is to prevent fuel flow at earlier stage for safety reasons?
fuel-systems
asked 9 hours ago
Mike no smith Mike no smith
855 bronze badges
$endgroup$
add a comment |
$begingroup$
Most GA planes have fuel shutoff vavle wich I don't quite understand the purpose of it if you can cutt the fuel flow with the mixture.
my theory is to prevent fuel flow at earlier stage for safety reasons?
fuel-systems
asked 9 hours ago
Mike no smith Mike no smith
855 bronze badges
$endgroup$
3
$begingroup$
If you're changing the mixture, doesn't that indicate the fuel is reaching the carb? Typically you don't want residual fuel sitting in the carburetor as it can break down and gum it up.
$endgroup$
– zymhan
9 hours ago
add a comment |
$begingroup$
Most GA planes have fuel shutoff vavle wich I don't quite understand the purpose of it if you can cutt the fuel flow with the mixture.
my theory is to prevent fuel flow at earlier stage for safety reasons?
fuel-systems
asked 9 hours ago
Mike no smith Mike no smith
855 bronze badges
$endgroup$
Most GA planes have fuel shutoff vavle wich I don't quite understand the purpose of it if you can cutt the fuel flow with the mixture.
my theory is to prevent fuel flow at earlier stage for safety reasons?
fuel-systems
fuel-systems
asked 9 hours ago
Mike no smith Mike no smith
855 bronze badges
asked 9 hours ago
Mike no smith Mike no smith
855 bronze badges
asked 9 hours ago
Mike no smith Mike no smith
855 bronze badges
asked 9 hours ago
Mike no smith Mike no smith
855 bronze badges
asked 9 hours ago
Mike no smith Mike no smith
855 bronze badges
855 bronze badges
3
$begingroup$
If you're changing the mixture, doesn't that indicate the fuel is reaching the carb? Typically you don't want residual fuel sitting in the carburetor as it can break down and gum it up.
$endgroup$
– zymhan
9 hours ago
add a comment |
3
$begingroup$
If you're changing the mixture, doesn't that indicate the fuel is reaching the carb? Typically you don't want residual fuel sitting in the carburetor as it can break down and gum it up.
$endgroup$
– zymhan
9 hours ago
3
3
$begingroup$
If you're changing the mixture, doesn't that indicate the fuel is reaching the carb? Typically you don't want residual fuel sitting in the carburetor as it can break down and gum it up.
$endgroup$
– zymhan
9 hours ago
$begingroup$
If you're changing the mixture, doesn't that indicate the fuel is reaching the carb? Typically you don't want residual fuel sitting in the carburetor as it can break down and gum it up.
$endgroup$
– zymhan
9 hours ago
add a comment |
3 Answers
3
active
oldest
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$begingroup$
It's both a maintenance and safety feature.
You need a way to cut off fuel flow to the engine compartment, either to work on the engine, or because of a fire at the engine, or because you are doing a forced landing and it helps reduce the risk of your entire fuel contents seeping onto your hot engine if you bend things a bit putting it down and a fuel line gets broken.
So you will always have a shutoff valve, and it's always somewhere upstream of the firewall.
answered 8 hours ago
John KJohn K
35.8k1 gold badge62 silver badges118 bronze badges
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add a comment |
$begingroup$
Fuel shutoff valves are a hold over from the days of float style carburetors (and necessary on any float style carb system). With a float style carb when the fuel is on the bowl will fill up until the float floats up and shuts the flow off. Since gasoline becomes a vapor at ambient temperature the small pool in the carb will be constantly evaporating. As such the float will sink and refill the bowl. Given enough time this will drain the fuel tank. This vaporous fuel also fills the intake and can cause backfires or intake fires.
The mixture is adjusted post bowl and merely leans you to the point of cutout which may not truly be a full stoppage of fuel.
For fuel injected systems or systems that use some kind of blow through carb a shutoff valve is not strictly necessary for leak reasons but JohnK makes some good points on when its used for safety reasons. Some of these systems will also allow small paths for fuel to escape so a shutoff is often implemented to ensure total fuel stoppage.
answered 8 hours ago
DaveDave
74.1k4 gold badges148 silver badges266 bronze badges
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The less technical, but accurate, answer is to meet the certification requirements of the FARs. Specifically, FAR 23.2430 is Airworthiness Standards for Fuel systems. It reads in part: (a)Each fuel system must-...(5) "Provide a means to safely remove or isolate the fuel stored in the system from the airplane"
answered 5 hours ago
AdamAdam
1,4386 silver badges10 bronze badges
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
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votes
$begingroup$
It's both a maintenance and safety feature.
You need a way to cut off fuel flow to the engine compartment, either to work on the engine, or because of a fire at the engine, or because you are doing a forced landing and it helps reduce the risk of your entire fuel contents seeping onto your hot engine if you bend things a bit putting it down and a fuel line gets broken.
So you will always have a shutoff valve, and it's always somewhere upstream of the firewall.
answered 8 hours ago
John KJohn K
35.8k1 gold badge62 silver badges118 bronze badges
$endgroup$
add a comment |
$begingroup$
It's both a maintenance and safety feature.
You need a way to cut off fuel flow to the engine compartment, either to work on the engine, or because of a fire at the engine, or because you are doing a forced landing and it helps reduce the risk of your entire fuel contents seeping onto your hot engine if you bend things a bit putting it down and a fuel line gets broken.
So you will always have a shutoff valve, and it's always somewhere upstream of the firewall.
answered 8 hours ago
John KJohn K
35.8k1 gold badge62 silver badges118 bronze badges
$endgroup$
add a comment |
$begingroup$
It's both a maintenance and safety feature.
You need a way to cut off fuel flow to the engine compartment, either to work on the engine, or because of a fire at the engine, or because you are doing a forced landing and it helps reduce the risk of your entire fuel contents seeping onto your hot engine if you bend things a bit putting it down and a fuel line gets broken.
So you will always have a shutoff valve, and it's always somewhere upstream of the firewall.
answered 8 hours ago
John KJohn K
35.8k1 gold badge62 silver badges118 bronze badges
$endgroup$
It's both a maintenance and safety feature.
You need a way to cut off fuel flow to the engine compartment, either to work on the engine, or because of a fire at the engine, or because you are doing a forced landing and it helps reduce the risk of your entire fuel contents seeping onto your hot engine if you bend things a bit putting it down and a fuel line gets broken.
So you will always have a shutoff valve, and it's always somewhere upstream of the firewall.
answered 8 hours ago
John KJohn K
35.8k1 gold badge62 silver badges118 bronze badges
answered 8 hours ago
John KJohn K
35.8k1 gold badge62 silver badges118 bronze badges
answered 8 hours ago
John KJohn K
35.8k1 gold badge62 silver badges118 bronze badges
answered 8 hours ago
John KJohn K
35.8k1 gold badge62 silver badges118 bronze badges
35.8k1 gold badge62 silver badges118 bronze badges
add a comment |
add a comment |
$begingroup$
Fuel shutoff valves are a hold over from the days of float style carburetors (and necessary on any float style carb system). With a float style carb when the fuel is on the bowl will fill up until the float floats up and shuts the flow off. Since gasoline becomes a vapor at ambient temperature the small pool in the carb will be constantly evaporating. As such the float will sink and refill the bowl. Given enough time this will drain the fuel tank. This vaporous fuel also fills the intake and can cause backfires or intake fires.
The mixture is adjusted post bowl and merely leans you to the point of cutout which may not truly be a full stoppage of fuel.
For fuel injected systems or systems that use some kind of blow through carb a shutoff valve is not strictly necessary for leak reasons but JohnK makes some good points on when its used for safety reasons. Some of these systems will also allow small paths for fuel to escape so a shutoff is often implemented to ensure total fuel stoppage.
answered 8 hours ago
DaveDave
74.1k4 gold badges148 silver badges266 bronze badges
$endgroup$
add a comment |
$begingroup$
Fuel shutoff valves are a hold over from the days of float style carburetors (and necessary on any float style carb system). With a float style carb when the fuel is on the bowl will fill up until the float floats up and shuts the flow off. Since gasoline becomes a vapor at ambient temperature the small pool in the carb will be constantly evaporating. As such the float will sink and refill the bowl. Given enough time this will drain the fuel tank. This vaporous fuel also fills the intake and can cause backfires or intake fires.
The mixture is adjusted post bowl and merely leans you to the point of cutout which may not truly be a full stoppage of fuel.
For fuel injected systems or systems that use some kind of blow through carb a shutoff valve is not strictly necessary for leak reasons but JohnK makes some good points on when its used for safety reasons. Some of these systems will also allow small paths for fuel to escape so a shutoff is often implemented to ensure total fuel stoppage.
answered 8 hours ago
DaveDave
74.1k4 gold badges148 silver badges266 bronze badges
$endgroup$
add a comment |
$begingroup$
Fuel shutoff valves are a hold over from the days of float style carburetors (and necessary on any float style carb system). With a float style carb when the fuel is on the bowl will fill up until the float floats up and shuts the flow off. Since gasoline becomes a vapor at ambient temperature the small pool in the carb will be constantly evaporating. As such the float will sink and refill the bowl. Given enough time this will drain the fuel tank. This vaporous fuel also fills the intake and can cause backfires or intake fires.
The mixture is adjusted post bowl and merely leans you to the point of cutout which may not truly be a full stoppage of fuel.
For fuel injected systems or systems that use some kind of blow through carb a shutoff valve is not strictly necessary for leak reasons but JohnK makes some good points on when its used for safety reasons. Some of these systems will also allow small paths for fuel to escape so a shutoff is often implemented to ensure total fuel stoppage.
answered 8 hours ago
DaveDave
74.1k4 gold badges148 silver badges266 bronze badges
$endgroup$
Fuel shutoff valves are a hold over from the days of float style carburetors (and necessary on any float style carb system). With a float style carb when the fuel is on the bowl will fill up until the float floats up and shuts the flow off. Since gasoline becomes a vapor at ambient temperature the small pool in the carb will be constantly evaporating. As such the float will sink and refill the bowl. Given enough time this will drain the fuel tank. This vaporous fuel also fills the intake and can cause backfires or intake fires.
The mixture is adjusted post bowl and merely leans you to the point of cutout which may not truly be a full stoppage of fuel.
For fuel injected systems or systems that use some kind of blow through carb a shutoff valve is not strictly necessary for leak reasons but JohnK makes some good points on when its used for safety reasons. Some of these systems will also allow small paths for fuel to escape so a shutoff is often implemented to ensure total fuel stoppage.
answered 8 hours ago
DaveDave
74.1k4 gold badges148 silver badges266 bronze badges
edited 7 hours ago
answered 8 hours ago
DaveDave
74.1k4 gold badges148 silver badges266 bronze badges
answered 8 hours ago
DaveDave
74.1k4 gold badges148 silver badges266 bronze badges
answered 8 hours ago
DaveDave
74.1k4 gold badges148 silver badges266 bronze badges
74.1k4 gold badges148 silver badges266 bronze badges
add a comment |
add a comment |
$begingroup$
The less technical, but accurate, answer is to meet the certification requirements of the FARs. Specifically, FAR 23.2430 is Airworthiness Standards for Fuel systems. It reads in part: (a)Each fuel system must-...(5) "Provide a means to safely remove or isolate the fuel stored in the system from the airplane"
answered 5 hours ago
AdamAdam
1,4386 silver badges10 bronze badges
$endgroup$
add a comment |
$begingroup$
The less technical, but accurate, answer is to meet the certification requirements of the FARs. Specifically, FAR 23.2430 is Airworthiness Standards for Fuel systems. It reads in part: (a)Each fuel system must-...(5) "Provide a means to safely remove or isolate the fuel stored in the system from the airplane"
answered 5 hours ago
AdamAdam
1,4386 silver badges10 bronze badges
$endgroup$
add a comment |
$begingroup$
The less technical, but accurate, answer is to meet the certification requirements of the FARs. Specifically, FAR 23.2430 is Airworthiness Standards for Fuel systems. It reads in part: (a)Each fuel system must-...(5) "Provide a means to safely remove or isolate the fuel stored in the system from the airplane"
answered 5 hours ago
AdamAdam
1,4386 silver badges10 bronze badges
$endgroup$
The less technical, but accurate, answer is to meet the certification requirements of the FARs. Specifically, FAR 23.2430 is Airworthiness Standards for Fuel systems. It reads in part: (a)Each fuel system must-...(5) "Provide a means to safely remove or isolate the fuel stored in the system from the airplane"
answered 5 hours ago
AdamAdam
1,4386 silver badges10 bronze badges
answered 5 hours ago
AdamAdam
1,4386 silver badges10 bronze badges
answered 5 hours ago
AdamAdam
1,4386 silver badges10 bronze badges
answered 5 hours ago
AdamAdam
1,4386 silver badges10 bronze badges
1,4386 silver badges10 bronze badges
add a comment |
add a comment |
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If you're changing the mixture, doesn't that indicate the fuel is reaching the carb? Typically you don't want residual fuel sitting in the carburetor as it can break down and gum it up.
$endgroup$
– zymhan
9 hours ago