Mark Sletten's comment that "There's no such thing as a fool-proof system" is right on. Unfortunately, even when you think you have a fool-proof system, nature provides a more determined fool.

This maxim was uppermost in my mind when designing the fuel system in my early 235 since I knew that everyone has, on occasion, found themselves in the "determined fool" pool - and that (according to the Fed's data) fuel systems and/or management was the contributory factor in a high percentage of Experimental accidents. With that in mind, I wanted as much redundancy (both in fuel transfer, engine supply and quantity monitoring) as I could think of.

As a result, I installed a Davtron fuel flow/totalizer for total fuel flow, a sight gauge on the header (yes, only close when the airplane is in level, unaccelerated flight, but a flight regime that can be attained), redundant wing-to-header pumps and a sure fire low-tech way (eyeball) to know unequivalently when a wing tank is empty. The redundant pumps are installed in series following the wing tank selector valve so that if one pump fails, the fuel in both wings is still available. The final requirement is supplied by a short length of transparent fuel line between the pumps and header that's visible by the pilot (located above the high-point of the wing tanks to prevent siphoning in case the transparent line fails).

Additionally, since I started flying my Lancair (in 1993), I have also religiously followed Mike DeHate's admonition (Mike checked me out in my airplane) to always plan to be in an airport environment when I'm down to 7 - 8 gallons in the header. For my small engine (O-235) that's 1 1/2+ hours. That reduced range is not a problem for me since, due to the "Pee Factor" referred to by Grayhawk, I've probably stopped earlier anyway!

Dan Schaefer
N235SP


--
I am using the free version of SPAMfighter.
We are a community of 6 million users fighting spam.
SPAMfighter has removed 678 of my spam emails to date.
Get the free SPAMfighter here: http://www.spamfighter.com/len

The Professional version does not have this message