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Date: Thu, 22 Mar 2007 12:40:06 -0400
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From: Lorn H Olsen <lorn@dynacomm.ws>
Subject: Re: fuel starvation due to leaky valve and one empty tank

Bob,

Don't replace a working technique for one that might work but will,  
for sure, cause more problems.

When I started flying 35 years ago my uncle (an old navy pilot) told  
me to run my tanks dry. He said that the last problem you needed on  
final with low fuel was to try and figure out where you had any fuel  
left.

In my first plane, a 4 tanked Comanche, I would takeoff and climb on  
the left main. I would then cycle through the tanks from left main to  
right aux to left aux to right main to left main. I did not have a  
fuel flow gauge but by the time I had burned the first tank dry, I  
could tell to within a minute when each of the other tanks would go  
dry. My last tank, the right main would always have at least as much  
fuel as I had calculated because it had only been flown lean.

I also had a C340 with 7 tanks. Same thing. I always ran them dry,  
except, of course, for the mains.

In my 320, I can only feed from the header. I always run the wing  
tanks dry into the header. I feel that this is the safest fuel system  
that I have ever flown with.

Keep your current good fuel handling habits.

Sincerely,
Lorn

> from "bob mackey" <n103md@yahoo.com>
>
> Tom, thanks for sharing this:
>
>> ... A factor that was not brought up was something that happened  
>> to Paul Loewen from Laser Plane Sales many years ago.  He flight  
>> tested a Mooney with one tank completely dry (I believe it was run  
>> dry so it
>> could have the fuel tank resealed). During flight testing, he  
>> ended up with a fuel starvation that was determined later to be a  
>> slight leakage of the fuel selector valve.  Air has much less  
>> resistance for the fuel pump than fuel does.
>>
>
> I have routinely run my 235 wing tanks try at high altitude before  
> switching to the nose. Doing so minimizes the unusable fuel, but  
> introduces a new risk from a leaky valve.
>
> I will rethink that practice, though I'm not sure how to make sure  
> there is still a gallon in each wing, as there are no fuel gauges  
> there. That's 16 pounds of flammable dead weight. I could add an  
> optical sensor with relatively little effort (another potential  
> leak). Or maybe I should just inspect and maintain that valve to  
> minimize the probability of internal leakage. Hmmmm.
--
Lorn H. 'Feathers' Olsen, MAA, DynaComm, Corp.
248-345-0500, mailto:lorn@dynacomm.ws
LNC2, FB90/92, O-320-D1F, 1,300 hrs, N31161, Y47, SE Michigan