EAB Crashes

There was a thread on another message board a couple days ago talking about the safety rating of EAB's. Unfortunately it quickly devolved into the usual, what had the potential of being a good conversation, wasn't.

However, two things that came out of the conversation that stuck with me. Supposedly the two major causes of EAB crashes are, Pilot Training, and fuel system failures.

In my mind at least, Pilot training is an easy one to fix (for me at least). Make sure I'm flying enough while I'm building to keep up my skills (I co-own a Cardinal), and go get some type training before first flight.

The more interesting comment was the fuel system failure. I'm getting ready to build the fuel tanks for my RV, and I'm looking at MOGAS, Fuel Injected, all of the other things folks generally look at as they decide what to build.

So my question is, what is it that causes the fuel system to be the failure point on so many EAB crashes, and what can I personally do to make sure I don't have an issue with my fuel system.

Thanks,

-Dan

I think the KISS approach to fuel systems is the best answer. As experimental AC builders, were are given a lot of latitude on how we build our planes. We need to be sure the systems we install are not overly complicated and are well executed. Like Scotty said " The more complicated the system, the easier it is to stop up the drain".

Roberta

robertahegy said:

I think the KISS approach to fuel systems is the best answer. As experimental AC builders, were are given a lot of latitude on how we build our planes. We need to be sure the systems we install are not overly complicated and are well executed. Like Scotty said " The more complicated the system, the easier it is to stop up the drain".

Roberta

Click to expand...

Roberta,

Ok, I agree with this in theory, but how does that translate to building a fuel system?

I.e. how do I build a simple fuel system, for a fuel injected RV-9, and allow for the potential vapor lock issues with burning mogas?

-Dan

See if you can find a certified low wing fuel injected airplane with an STC for auto gas... then copy it...

dweyant said:

Roberta,

Ok, I agree with this in theory, but how does that translate to building a fuel system?

I.e. how do I build a simple fuel system, for a fuel injected RV-9, and allow for the potential vapor lock issues with burning mogas?

-Dan

Click to expand...

I think that you are assuming that vapor lock is the failure mode that is bringing down AEB's when they have fuel system problems, and while some may be, I doubt that this is the predominant reason. This is where statistics fail (utterly) in preventing accidents - you need to actually read the causes of the mishaps, then come up with a way around the particular problem that caused it. You will probably find few RV's, built to plans, that have had such problems. Therefore, build an RV to plans, but with materials that are compatible with Ethanol, and you shouldn't have any real problems.

As Roberta said, keeping fuel systems simple is a huge factor in building a reliable system - and few can argue that Van's system is simple - it has been used for decades on countless airplanes, and works fine.

Paul

dweyant said:

Roberta,

I.e. how do I build a simple fuel system, for a fuel injected RV-9, and allow for the potential vapor lock issues with burning mogas?

-Dan

Click to expand...

For me, it was not just about the plumbing, but the fuel system as a whole. I wanted a simple system that was easily adaptable to future fuels while allowing me to get the optimum performance and economy out of my engine without all the voodoo that gets talked about on this forum or the $1000+ seminars that try to explain the voodoo. I wanted a simple, easy to install and maintain system that provided feedback that all is well and functioning normally.

I am using Precision's Eagle EMS (mfg of certified FI and Experimental Silverhawk FI) in my IO-320 C/S RV-9A. It provides both dual electronic Ignition and electronic fuel injection in a single system. It was a good route for me to simplify my fuel system and better support future fuels, including mogas, while managing my Ignition and air/fuel ratio to provide best power and best economy cruise without the voodoo. I am given a lean pot to lean by a percentage, but for mine full lean automatically sets it up for best economy cruise, not matter what power setting or altitude. Should I try to over lean and cause the cylinders to rise over 400 degrees, it will ignore my input and adjust timing and fuel to keep temps down. It's simply to install and made to be a direct replacement for other Mag/EI and carb/FI installations.

I used standard hard-pipe plumbing from the wings through the fuel selector to the firewall. On the engine side, I used professionally custom-built fuel lines from the firewall to the mechanical pump and than to the fuel block on top of the cylinders. Unlike standard/mechanical FI, this is NO hose from the mech pump to the throttle body, thus no line going from the throttle body between the cylinders (cooking the fuel) to the distributor block. Note: This isn't really a distributor block per se, it contains a micro filter and dual pressure sensors.

Each injector is individually pulsed at a much higher pressure than mech FI, thus quickly clearing out any vapors. Injectors lines are larger and insulated/fire sleeved. There is no need for a fuel flow sensor spliced into your main fuel line since the computers(s) know exactly how much fuel was consumed bases on the pulse length and fuel pressure. Much more accurate than traditional flow sensors. The throttle body is the same as the Silverhawk, except it has dual MAP/Temp sensors connected to it.

I flew to AirVenture2012 and landed at airports that were above 100+ degrees with high density altitudes. Engine had plenty time to heat soak, but it started just like a car and immediately adjusted for density alt. On take-off/climb, it always maintained best power until reaching cruising alt when I switched to best economy cruise.

Although not everyone wants to try something new, I would do the following regardless of what fuel system I would install. I would personally avoid anything that adds more fuel lines and/or connections. I wouldn't add a aux tank or use any FI system requiring a return line. It only complicates the fuel system, adds more connections that could leak or fail and makes it difficult to manage/calculate fuel consumed from each tank, especially with return lines.

If you want to use mogas, I would use as much hard pipe as possible unless you are willing to replace your fuel hoses on a regular/scheduled interval. Also, have a pro make your hoses!! Confirm that the mfg of your mech pump and fuel system are ok with mogas.

NOTE: I am not a A&P nor do I pretend to be. These are just my personal comments based on my experience or lack there of. However, I have stayed at a Holiday Inn numerous times!

My .02 cents worth, good luck.