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xCountry22

Member
This may seem like a basic question to many of you and I don't want to kindle carb vs. FI wars, but I was interested in a comment made on the RV accident thread. Someone identified fuel system problems as one area of note in some accidents.

I'm in the process of evaluating carb vs. FI and on the 'reliability' issue alone, does anyone have a POV or thoughts for this relative newbie?

I'm well into my wings with QB fuse on the way. I need to start thinking of engine choice soon.
 
I started out kind of paranoid about E/AB airplanes, so I read a lot of NTSB reports. I still read up on every accident I can to see what can be learned to try to avoid repeating the event. It's not the fuel delivery mode (carb or FI) that breaks airplanes and kills pilots, it's the builder's (or maintainer's) design and execution of it.

The best carburetor or fuel injection system ever devised by mankind doesn't work if you don't give it a chance. Don't slather RTV on the fittings and choke off the flow, or fail to clean it out so the filter clogs on takeoff, or fail to put gas in the tanks, or put sharp bends in the fuel lines so they kink, or rig things so safety wire or cables saw through fuel lines, or any of the other stuff people have done to explore the glide ratio performance of powered aircraft.

Just my humble opinion.
 
DaleB said:
It's not the fuel delivery mode (carb or FI) that breaks airplanes and kills pilots, it's the builder's (or maintainer's) design and execution of it.
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Very true. Go with whichever system meets your needs but build and maintain it to certificated (or better) standards. It is possible to have a rock solid fuel system in EAB if established procedures are used for construction. Don't get experimental unless you have the engineering background to anticipate unintended consequences.
 
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Sam Buchanan said:
Don't get experimental unless you have the engineering background to anticipate unintended consequences.
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I want to really emphasize this part of Sam's comment - it's exactly the correct take-away message.

Things can be changed from the "tried and true" in our experimental aircraft without much (or any) oversight - but new configurations bring out new "gotchas" that have to be considered. It's not that we cannot or should not change things, but we need to sit down and carefully consider what might happen in various scenarios before we pick up the tools.
 
low pressure fuel, carb

I like my simple low pressure fuel system and carb for non-acro. use a good carb heat muff. trade-off is carb icing concern, it's real.
 
The standard RV fuel system is working fine on thousands of aircraft all around the world. Yet some builders design their own fuel systems with "enhancements" that cause fuel starvation issues down the road.
 
It's the basics that seem to cause most of the fuel related events. Things like using non-approved materials, cutting corners by not learning how to properly flare a fuel line, or how to properly torque an AN fitting...or when it's proper to use a thread sealant and when it's not. Read the applicable authoritative texts on the proper techniques (AC 43.13-1B (http://www.faa.gov/regulations_poli....cfm/go/document.information/documentid/99861), and the Aviation Maintenance Technician Handbook (http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_handbook) to name two of them). Of all things that can go wrong on a homebuilt plane, the fuel system has a high potential to end up killing you. It is not a place to experiment...stay with the well-known materials, and techniques.
 
My Take

As one of those that plumbs fuel systems, I certainly agree to keep it simple, and as conforming as possible. I agree with all of the statements. Investing in the proper tools AND the time to use them properly, pays huge dividends in our builds, and the reliability of our planes.

Tom
 
As a reminder, it isn't always the tools or fittings but how the system is installed.

This thread is a great example of how making changes, such as running the fuel line "in the coolest part of the engine compartment" can cause problems. (Granted, in that installation there were many issues which were addressed by the second owner.)
 
Beware

Beware of the "Waddington effect." I had the right engine quit on a 310 as the wheels retracted. It was fresh out of an annual inspection and the fuel line came off the spider. It had been started by hand and never saw a wrench.

Mr. Waddington saw much of this during WWII and told the authorities to stop doing unnecessary maintenance on the bombers and they immediately saw over 30% less post-maintenance issues.

We've had that issue on here...fuel lines not tightened either during assembly or after maintenance.

Best,
 
pierre smith said:
Beware of the "Waddington effect." I had the right engine quit on a 310 as the wheels retracted. It was fresh out of an annual inspection and the fuel line came off the spider. It had been started by hand and never saw a wrench.

Mr. Waddington saw much of this during WWII and told the authorities to stop doing unnecessary maintenance on the bombers and they immediately saw over 30% less post-maintenance issues.

We've had that issue on here...fuel lines not tightened either during assembly or after maintenance.

Best,
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I agree with Pierre completely. The "annual" inspection process creates problems that did not exist, it's happened a lot.

Back to the original question, the answer is not in the NTSB reports. It is in building a fuel system that is known to work. Its as simple as that. Stick with the plan and don't loose sleep over it.
 
Back to original question

Good discussion, but my original question was about any differences between a standard carburetor or FI configuration as far as reliability is concerned.

Standard is challenging enough for me. No way on mods.
 
xCountry22 said:
Good discussion, but my original question was about any differences between a standard carburetor or FI configuration as far as reliability is concerned.

Standard is challenging enough for me. No way on mods.
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The short answer is both are reliable.

The difference is personal choice. I've had both and like fuel injection.

There are guys here flying with a carb for hundreds of hours.

The carb is less money.

Fuel injection does not required heat.

Flying LOP is easy with injection but works with carb also, just not as precise.

Figure out what YOU want and go for it.
 
xCountry22 said:
Good discussion, but my original question was about any differences between a standard carburetor or FI configuration as far as reliability is concerned.

Standard is challenging enough for me. No way on mods.
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Your question was answered early in the thread. Reliability won't be dependent on which system you choose (both have been in service for decades), it will depend on how well you install and maintain the system of your choice.
 
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