First fill of the tanks

[brendanw]

So, in preparation for the upcoming first engine start, I need to plan the first fill of the fuel tanks. And I imagine that this would be one of the best opportunities to mark the level indications on the sight gages. Thoughts and questions...

 

(1) I spoke with a lineman at the FBO on the field at KWST regarding the fuel pump. I asked if he can accurately (± 0.2 gallons or so) stop the pump every 5 gallons so that I can mark the sight gages. He said yes. Does this sound like a good idea?

 

(1a) What graduation does everyone typically use? 5 gallons seems about right given the ~10 GPH burn rate of my O-360

 

(1b) What do you mark the sight gages with? I was counting on an indelible ink marker (Sharpy), then making up the numbers on the labeling machine.

 

(2) Not that I think I'll have any catastrophic problems (knocking on wood now), having two full fuel tanks on the first engine start is way more than I need and I suppose could be a safety issue. In this case though, I'm not sure that 5 gallons is any less of a safety risk than 50 gallons. Thoughts?

 

(2a) I suppose that once I fill the tanks and mark the gages, I can drain the tanks (I'm going to need a bunch of tanks!!!) through a paint filter and clean out any debris that may have gotten in there. Thoughts?

 

(2b) I can then refill the tanks to, say, the 5 gallon mark with my filtered fuel. Thoughts?

 

(3) I suppose I could avoid all of this at this point by feeding the engine from an external tank via some bastardized plumbing sequence. Thoughts?

 

Getting exciting now!!

[Waiter]

Everything sounds good (except the feeding the engine with basterdized tank, don't do that)

 

Additional thoughts:

 

1) Instead of the normal low point strake sample drains, install some El-Chipo ($3.00) ball valves in each of the drains. This will make the draining process a lot easier, cleaner, AND safer. Just connect a short hose onto the valve, open the valve and drain the strake.

 

When your all done and everybody is happy, remove the ball valves and reinstall the sump sample drains

 

2) When you mark / calibrate the fuel guages, the plane should be on all three, with about a 2 deg nose up deck angle (Measured on the top longerons). You may need to place a spacer under to nose tire to raise it up to the 2 deg angle. This is your normal cruise deck angle. Place a couple heavy weights in the front seat to keep the plane from falling over backwards, AND tie the nose down if possible.

 

3) While you have fuel in the plane, remove the hose from the carb, run your electric pump and fill a couple 5 gallon cans via the carb hose. Repeat this with both strake tanks. This will flush the lines.

 

IMPORTANT, Check the finger strainer, fuel filters when finished. If there is any debris in the filters, repeat the process until the filters are clean.

 

 

Waiter

[longezdave]

How about a fuel flow rate test?

[Kent Ashton]

I put in about 4 to 5 gallons per side and checked for unrestricted, adequate flow into the gascolator fitting and I filtered the gas into a can. Then I checked the gascolator screen for debris and put approximately 10 gallons per side back into the tanks. I did the first few flights with very rough quantity markings--just something to satisfy the inspector, then after a couple of hours I drained the remaining gas and did the same fill procedure you discussed and marked the tanks at 5 gallon intervals for some serious test hours.

 

I also checked the gascolator screen and filters again after a couple of hours of flight testing.

[brendanw]

Thanks for the feedback guys. Very helpful.

 

Here's what I ended up doing:

 

- Pulled the gascolator inlet line off and installed a ball valve from the plumbing section of the hardware store.

- Filled a 5 gallon gas can 4 times and dumped 5 gallons at a time into the left wing, marking the sight gage at each 5 gallon mark. Note: the self serve pump at KWST allows you to program in 5 gallons, rather than $20 or whatever. very helpful.

- I sloshed the fuel around in the left tank to rinse it as much as I could, then drained 10 gallons (5 gallons at a time with a paint fileter) to put into the right wing, making the first two marks on the sight gages. I didnt find any contaminates at the gascolator, but the sump screen might be holding onto some bigger stuff.

- Reattached the gascolator (left the right wing clean-out for a later date)

- Pulled the line off the carb and used the boost pump to fill a one-gallon jug from the left wing and timed it. 2 minutes and 5 seconds, or about 30 GPH... cool! Filtered that fuel and put it back into the left wing.

 

List of things to do:

 

- slosh the right wing, drain the fuel and filter it looking for contaminates.

- pull the gascolator and fuel filter out to check for contaminates.

- pull the sump drains and drain a bunch of fuel directly form the wing to look for any big chunk that may be getting to the sump screen

- continue filling the right wing and make the rest of the sight gage marks.

[Waiter]

You need to test your fuel flow through the entire circuit (through the gasculator) and into the carb

 

Take the fuel line off at the carb, then gravity feed to fill a five gallon can, WITHOUT the boost pump.

 

Make sure you enter these numbers in your builders log. You DAR or FAA may want to see them.

 

Waiter

[brendanw]

Take the fuel line off at the carb, then gravity feed to fill a five gallon can, WITHOUT the boost pump.

The flow rate test that we performed did, in fact, go through the entire circuit. We pulled the line off of the carb and pumped fuel through WITH the boost pump. This is where the 2:05 for one gallon came from.

 

So you're saying that we need to log the gravity (WITHOUT boost pump) flow rate through the circuit? I imagine that number would be pretty small. Is that intended so that we know what the flow rate would be if the mechanical and electrical pumps crapped out? It wouldnt account for advantage gained from the vent line 'pressurization' of the tanks in flight.

 

Anyway, it wouldnt be hard to run the test. Thanks for the info.

[ZUCZZ]

I did the flow test like that ... gravity wise and proved (to myself) that if it all turned pearshaped that you could keep the show in the air with the flow available ... fuel flow wise, that is without motor turning :-)

 

regards

[Terry]

For the gravity flow test to be valid the the outlet of the hose must be at the level that it hooks to the carb. if it is lower it will give a false higher flow rate.