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  #11  
Old 01-23-2022, 09:17 AM
Deweyclawson Deweyclawson is offline
 
Join Date: Jun 2014
Location: Enon Valley
Posts: 202
Default plugged fuel line

How long can you run on just gas down stream of the plug in the fuel line?
I have no way of intentionally plugging a line, short of the off position, so I have no answer to this, but occasionally read of someone who was unknowingly trying to find out.

If you had a plugged line, the best case would be to find it on the ground. How long would you have to run to do that?
Worst case would be to find it just after T/O.
Door #2: In between the above 2 options is to find it at cruise altitude at a location of your choice.

I'll take door #2.
Always start, taxi, T/O on the same tank.

JMHO, YMMV
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  #12  
Old 01-23-2022, 11:42 AM
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RV7A Flyer RV7A Flyer is offline
 
Join Date: Jul 2013
Location: US
Posts: 2,653
Default

Quote:
Originally Posted by Deweyclawson View Post
How long can you run on just gas down stream of the plug in the fuel line?
I have no way of intentionally plugging a line, short of the off position, so I have no answer to this, but occasionally read of someone who was unknowingly trying to find out.

If you had a plugged line, the best case would be to find it on the ground. How long would you have to run to do that?
Worst case would be to find it just after T/O.
Door #2: In between the above 2 options is to find it at cruise altitude at a location of your choice.

I'll take door #2.
Always start, taxi, T/O on the same tank.

JMHO, YMMV
I honestly don't know the answer to this, but I think a simple experiment with a straw or piece of tubing would answer it...if a line is plugged, is it even possible for the fuel that's in the line past the plug to get sucked out by the pump? Assuming a complete blockage, with no way for fuel or air to get past the block, wouldn't that prevent the suction from being able to pull fuel?
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  #13  
Old 01-23-2022, 11:45 AM
wawrzynskivp wawrzynskivp is offline
 
Join Date: Feb 2018
Location: Incline Village Nv
Posts: 312
Default

Quote:
Originally Posted by Deweyclawson View Post
How long can you run on just gas down stream of the plug in the fuel line?
I have no way of intentionally plugging a line, short of the off position, so I have no answer to this, but occasionally read of someone who was unknowingly trying to find out.

If you had a plugged line, the best case would be to find it on the ground. How long would you have to run to do that?
Worst case would be to find it just after T/O.
Door #2: In between the above 2 options is to find it at cruise altitude at a location of your choice.

I'll take door #2.
Always start, taxi, T/O on the same tank.

JMHO, YMMV
Put the 'E' in our experimental category. Shut it off and find out?
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  #14  
Old 01-23-2022, 11:49 AM
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Dan 57 Dan 57 is offline
 
Join Date: Sep 2018
Location: LSZF
Posts: 961
Default

Quote:
Shut it off and find out?
Whilst on the ground… would be safer
Same test is used to test the fuel valve OFF position.
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  #15  
Old 01-23-2022, 12:26 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 1,131
Default

I know a Cessna has just enough fuel in the carb bowl to taxi out and almost break ground before it quits. Probably can’t get that far of you include the run up on that bowl gas. Another scenario could be a plugged fuel tank vent. I would bet you could get some more time with a plugged vent than just a plugged (or valve off) fuel line. Also having a half tank and a plugged fuel vent probably would give you more time before the tank negative pressure is enough to starve the engine.

Needless to say, I prefer to start, taxi and perform the run up on the same tank. Then after 30 minutes, make the first tank switch so if there’s a problem, you have the altitude, time, and remaining fuel in the first tank to go back to.

I spoke to an old toner out of Homestead Florida who told me stories about the Fed’s contacting him to reposition planes that the drug runners would land and abandon on the levies in southern Florida.. Beech 18s, DC3s ect.. he would always take off on whatever tank they landed with. His theory was it probably landed with enough fuel to take off with!
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  #16  
Old 01-23-2022, 05:02 PM
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skylor skylor is offline
 
Join Date: Aug 2009
Location: Southern California
Posts: 1,045
Default Fuel Selector Usage

I follow the recommendation of the late John Deakin when it comes to fuel selector usage and that is to avoid switching tanks while on the ground. Essentially, if you use the fuel system as configured the last time the plane flew under power then odds are in your favor that it will operate correctly on the next take off. The trick for this to work well is to ensure that you always select the fullest tanks sometime before landing and/or fuel the plane after landing.

My thoughts on this are as follows:

1. Operating the fuel system “as set” during the previous powered flight helps to ensure that the system is in a “known good” configuration for the next takeoff.

2. The ability to start, idle, and taxi on one tank does not prove that the fuel system doesn’t have a partial blockage or suction side leak. These types of issues often only create problems under high fuel flow but not at the low flows required for idle and taxi.

3. If you always ensure that fuel selector changes in flight are performed at safe altitudes and with emergency landing options available and identified, then an engine failure due to a fuel system problem should not become a life threatening emergency. An engine failure at the wrong time during takeoff and initial climb out IS a dangerous situation.

4. I’m always extra cautious after maintenance has been performed on the fuel system because this increases the potential for problems and the system is no longer “proven” from the previous flight.

Skylor

Last edited by skylor : 01-23-2022 at 05:05 PM.
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