I agree that both tanks prefered landing position, but if you have exhausted a tank which is sometimes neccesary, and you need to slip aircraft for landing or altitude loss, just remember to keep the wing with fuel in it to the high side of the slip. If you slosh that tank to the outboard side of tank or wing low uncoordinated, you will scavenge fuel out of all the plumbing, gascolator, etc and once fuel re-introduced to the pick up line, it will take awhile for the engine to start making noise again. And in a landing situation, near the ground, you're liable to come up short if that power is needed?

Something else I remembered to keep in mind, from Jeremy's previous post, the fuel line from the left tank is shorter and so the left tank will feed quicker than the right when on both.
I did lose one of my aux pumps on a long crosscountry (Missouri to Idaho) and had to land, move 10 gallons manually, then leave that there and was restricted to using only the other tip tank. Made a crosswind in Wyoming difficult at 9000' and 90F,
Dave

All,

I have to agree with Skeletool. I downloaded the Fuel Timer app two days ago and to be honest, I was skeptical at first - I almost didn't purchase it... BUT...

For a few bucks I was very impressed. It's really simple - you setup fuel burns for each phase of flight. Make sure you click save after each section...this was a little confusing to me at first. The app reminds you to switch tanks, and then you tell it which tank you just switched to. Between the fuel burns, the phase of flight, and the tanks, it knows EXACTLY how much you've burned. From my measurements it's accurate to about 1/10 of a gallon.

Also, I like to fly out for 30 minutes, then switch tanks every hour. This app lets you set that up with an 'initial' switch tanks timer and then a 'recurring' switch tanks timer which can be a different amount of time. Ingenious.

WAY, WAY better than trying to use egg timers and 30 minute timers on my 496. Those don't tell me how much fuel I have in each tank, and definitely not nearly as accurately. I think these guys are onto something here - an instructor on the field said he downloaded it last week and was using it with his students.

BTW - I also use the 496 timer, and in fact my 430 has a switch tanks reminder also. However, there are reasons why I don't always follow those switch tanks reminders - like when I'm REALLY far from a landing spot, or when I know I JUST started the airplane, or when it goes off right before I'm about to take off. This app lets you stay in control of the switching while monitoring the fuel accurately.

The iPhone/iPad/iPod app solution is way better - no question. This is a simple concept - I'm really surprised nobody came up with this sooner.

It's available here in case you don't have the link: http://bit.ly/oBAYbA

Thanks again for the tip Skeletool!

LIA

One reason for using fuel in smaller segments that has not been mentioned is if a single tank is used for a long period the opposite wing gets a bit heavy in flight and if you have a cross wind from the "empty" side it is more difficult to get the wing down into the wind.

On a related issue now winter is coming on.

It probably is a good idea to check your aux pumps for water before freezing temps arrive.

A few years ago I was happily flying along in Eastern Washington at an OAT of about 0 F and had routinely turned on my aux pump to transfer the 10 gal out of the aux tanks. In a few minutes I noticed my right main ( which I was not pulling from) was not getting any more full. I really did not need the fuel, but it was an eye opener.

Turns out there was water in the aux pump and the fuel was not being transferred. Once I was down to warmer air it transferred just fine.

I also have had a problem with an aux fuel pump. I had full aux tanks on a long cross country but the fuel stop that I'd planned was closed by the time I arrived so I continued on thinking that I had sufficient fuel in the aux tanks to make it to my destination with plenty to spare. I switched the aux tank pumps on in flight and after a while noticed that my left aux tank fuel gauge reading was not decreasing, although the right was ok. Turns out the aux fuel pump had failed in flight and I had 15 gallons less fuel that I planned. Not an emergency but something to think about during your flight planning.

In a little over 4000 hours I have had two aux pump failures. The first time I didn't catch it. Landing with one aux tank full and the other empty is a handfull. Luckily the full tank was the wing that need to be down in the crosswind. Now I monitor the tansfer process closely to make sure things are going as planned.

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