Fuel system changes, and second test flight.

It's been 9 days since the first flight.  Been working to understand the header tank issue so I can fix it.

First was to essentially redo the fuel flow test to understand if the vents are working properly and fuel / air can move where they need to move.

For the first flight the header tank venting system went like so:

• From the header tank, two vent lines come out of the top and run horizontally towards each wing.
• Make a 90 and head aft and go up the door frame.  From there they go along the top of the door to the wing hinge just forward of the aft spar.
• Then they make 180 and go forward and are attached to the root rib.  They transition around the forward spar and then into a conduit along the leading edge of the wing.
• They exit the leading edge at the tip and are T'ed into the vents from the main and aux tanks.  
• Then into a Andair checkvalve, then to the JD airparts vent under the wing.

The problem with this... the big U from the door back to the leading edge could be a P trap.  I did it this way so you can still easily fold the wings.

So I changed all this.  The vent now exits the fuselage at the leading edge of the wing and goes straight down the leading edge.  It is now always uphill to the wingtip.  All of this was accomplished in a couple hours.

Then to test...

Ran many, many tests.  The summary of what I found.  

1. The fuel flow with the original and new vent configuration is the same.  
2. The right wing was transferring fuel averaging 30% slower than the left.
3. I separated the vents at every point possible and redid the test.  Was always within a couple percent of each other.

The focus then became why is the right wing transfering fuel slower?  It wasnt the vent.

• Folded the wings (again).  Took out the finger strainers.  Strainers were clean, but there was construction debris (what my friend Geoff calls 'sworf').  Cleaned.  Tested again, no change.
• Focused on the areas between the wing root and fuel selector.  Drained the lines, took every fitting apart and checked.  Found some shitty pipe ends that needed some filing.  
• Removed the fuel valve.  Tested from the wing to the input of the fuel valve.  Both sides where identical.
• Did a flow test on the fuel selector.  Same on both sides.
• The lines from the wing to the fuel selector are 3/8".  The output of the fuel selector to the header tank was also 3/8".  No bueno.  I had the right fittings to change that to 1/2".  Header tank removed.  Drilled and retapped the tank (luckily the boss was HUGE).  New 1/2" fitting on the header tank.
• Reassembled EVERYTHING and tested.  Now the flow is within 5% of each other.  On BOTH the fuel flow is considerably faster.

I tried to find fittings for the header vent at the wing / fuselage intersection.  Everything I tried leaked.  Finally just put in a short hose coupler with some clamps.  No leak.

Slept... tested again in the morning.  Still good.  Put the rest of the interior back in, wingtips back on, cowlings on.  Time to fly.

So I repeated the first flight.  Overhead the airport.

On the first test flight the header tank warning went off 26 min into the flight running at 13 GPH, 1500 feet.  So i did that again, but for 45 minutes.  Rock solid.  For the next 15 minutes I played with different power settings from 5 GPH to 15 GPH.  Still solid.  Landed without incident.  Airplane and pilot reusable.  Success!

No crowds this time.  No fanfare.  Just me and the Sportsman.

I put 40 lbs of stuff in the back and tied it down.  Move the CofG aft a bit.

Takeoff was great.  Climbed very quickly.  Setup an orbit at 1500 ft.  No alarms... only green LED's.

So that was flight test #1 repeat.  No audio issues.  My landing still sucked :-).

First Flight!

I really didnt think many people read this blog... but I've had a number of people say 'where is the update?  did you fly yet?'.  Yes, I did.

It was a mad dash to get everything ready.  Had to get my insurance checkout, test all the little things that were keeping me up at night, find a decent weather window, align with my co-pilots schedule, and the winds had to be favourable.  All of that lined up on March 27, 2026,.

https://youtu.be/oc1EFEI_bHI

All in all it went extremely well.  The pilot and airplane are reusable!

I tested everything, multiple times.  The rigging was checked over and over.  Every snag I knew about was fixed.  Had many sets of eyes on anything that was questionable.

We briefed.  Scott reviewed everything that was different about GVSW.  We planned the flight in detail.  Talked about what we would do if X happened.  

Normal start up.  Normal run up.  We taxied to the end of the runway and applied power.  She tracked straight down the runway and leapt into the air.  Climbed to 1500' and orbited the airport.

We had some COM issues.  First the intercom was staticy.  I figured out why... imbalance between the headset gain and intercom gain.  Easy fix.  When troubleshooting this I accidentally isolated scott.  That was on me as I did not fully understand how the isolation feature worked (now I do).

At about 26 minutes into the flight the header tank low warning went off, so we headed back to the airport and landed uneventfully, except my landing was not optimal.

All the engine temps were good.  No alarms other than the header low warning.  Intercooler worked well... temp into the engine was max 42 degrees during the climb, and 37 degrees in a high cruise condition (13 gph).

Now onto figuring out why the header low warning alarm went off.

All in all was a great day.

Update!

Posting an update... the last few weeks have been a blur.

A very large (if not the largest) number of E-AB issues on first flight are fuel related.  Specifically modifications to the fuel system, which I have done with the addition of the header tank and vents.

A good friend and mentor is going to come along for the first flight.  He has done many first flights, mainly in RV's.  He has a wealth of experience, is a good friend, and a wonderful person.  He mentioned this stat... his concern (and mine) are the header tank vents.  Specifically how they are all tied together under each wing tip.

His recommendation was to get a couple shop vac's on 'blow' and hold them up against the vents to verify the header stays full.  Ran this by a couple of my fellow UL builders, and the recommendation was to use leaf blowers instead as they have higher wind speed.

So this took me down an interesting side road.  How fast do leaf blowers 'blow'?  Google said between 150 and 200 MPH.  OK, that would work.  Purchased an anemometer from Vevor that would do 101 MPH.

I have a plug in electric leaf blower that was my Dad's in the hangar.  Let's start there... 81 MPH.  Huh.. .that is not enough.  A neighbour had a Ryobi cordless one... let's try that.  Slightly better... 83 MPH.  Not going to work...

I thought I could print some nozzles that would increase the air speed.  Designed one and printed it... EPIC FAIL.  It actually slowed the air down.  Found one online for the Ryobi and it wouldnt fit... was a good 1/4" out.  There are a lot of different models of Ryobi leaf blowers apparently.

Next was to grab my Stihl cordless from the house.  100 MPH!  OK, now we are talking.  

Another friend had a Stihl gas powered.... well it put the anemometer into overload.

Couple ladders to rest them on and two willing victims to hold them...

The 2/3rds header tank alarm never went off.  Ran at 10 GPH for 10 minutes.  That should have run over 1.5 gallons through the 2.2 gallon header.

After the initial euphoria of a successful test wore off I got thinking...  what if the header is not full... will it refill?  So going to do another test with that configuration.

I've had an ongoing issue of fuel leaking out of the filter assembly.  I got it down to less than a weep, but there was still fuel on the fitting.  Changed out the copper gaskets on the suction collector, still leaked and now started coming out of the seam in the reusable input filter.  Finally just took the whole thing out, replaced every gasket, torqued and reinstalled.  That got it.

Then there was the brake leaks.  This has been ongoing... months ago it was leaking out the park brake valve.  Rebuilt it with a kit from matco and had it pressure tested... no leaks.  Reinstalled... was fine for weeks and weeks... then it started leaking.  I think it was coming from the shaft.  I am tired of cleaning up 5606.  Pulled out the valve and put in 2 union fittings.  While testing, found a leak on one of the hoses on the co-pilot side.  Removed, re-terminated, pressure tested, fixed.  Reinstalled.  No more leak.  Plus endless cleaning of 5606.

Tweaking cowl fasteners for fit and height.

Anti chaff tape on flaps.

Polishing continues.

Went down to WA state for a checkride with an experienced Glastar / Sportsman instructor.  This was needed for insurance purposes.  Done!  Great airplane to fly...  

Friends have been asking for ages 'are you excited'?  Honestly I was not... had work to do.  NOW I am getting excited!  Last hurdle to first flight is passed.

Putting the interior back in today, test the vents tomorrow (Wednesday).  Fix any last minute gotchas on Thursday, fly Friday (3/28) weather permitting.  As of Tuesday, it's looking awesome.

Setting fine pitch stop on prop

Need to set the fine pitch stop on the prop as part of the installation process.

Basic process:

1. Tie plane down.  
2. Warm engine, run up to full power
3. Note RPM
4. Set prop to manual.  Adjust to get 100 RPM less than prop setting for takeoff.
5. Adjust fine pitch stop cam.
6. Repeat until correct.

Engine ran great.  One small adjustment and was good to go.

Final Assembly after Final Inspection, and Next Steps

Getting exciting now.  I would be more excited if I wasn't so tired.

The biggest thing after inspection was to get the interior reassembled.  Some pieces havent been installed in years... like the forward tunnel covers.  They were quite dusty.

Floorboards bolted in, and CARPET installed!  I didnt realize that the carpet had to go in before the seat tubs.  Now I do.  Anti chaff tape on all contact areas.  Seat tubs and seats installed.  Center seat belt components installed.

Rear control cable covers installed.  Rear seat back installed.  Cargo floor installed.  ELT armed and bulkhead A cover installed.

Right wingtip installed (removed for inspection).  All inspection covers installed.  2 were missing.  One found, and had some spares of the smaller covers.  That one needs paint.

Installed the gear leg fairings and silpruf'ed them on.

Next steps / what's left...

1. I have a fuel weep out of the collector to the fuel filters. Need new copper gaskets.  Going to get them tomorrow.
2. Training!  Need a check out by a commercial pilot in type.  I have a contact, need a good weather day or two.
3. Test plan.  I have the EAA test cards.  Need to review.
4. Polishing... the polishing is ongoing, but it is not going to stop the first flight.

Final Inspection

Well after weeks of work, the big day finally arrived.  Final inspection!

I talked to my inspector the night before to verify something, and learned I needed a bunch of copies of multiple items at the ready.  So caught that in time.

The doors were back in the paint shop to fix the clear coat.  Arrived at 6:30 to get the hinges back on and get them installed.

The inspection itself was pretty much what I expected.  He went through:

• All control systems.  All stops, all pulleys, all cotter pins.  Checked proper operation.
• Checked all trim tabs for correct operation
• Checked for all required placards
• Checked that all speed markings (V speeds) were correctly setup.
• Checked weight and balance
• Checked maintenance schedule
• Checked fuel flow test report
• Checked all required log book entries
• Ran engine.  Checked for any leaks.  Checked operation of all engine instruments.

The above is a partial list.  Was 3 hours overall.

And I passed.  The next day he hand delivered my Special Certificate of Airworthiness and Operating Conditions.

That was pretty awesome.

Now its onto reassembly.

All the little details...

So many things to finish.  

Final inspection schedule for somewhere between March 3 and 5.

I havent posted much because I have been so busy...

Log books are done.  Engine, Prop, Airframe and Journey logs.  POH is written.  Checklists are written. Maintenance manual is written.

Fuel flow test report is done and written.

TC's application for special cert of airworthiness.  Done.  All 3 copies.

Header tank has been removed, new bungs added, refinished, and reinstalled.

New level sensors for header tank obtained and installed.  New monitor board, indicators, and software complete.

Interior placards done.  Exterior placards waiting on polishing to be finished.

Paint touch ups done.

Tanks calibrated.

Fuel system leak found and dealt with.

Park brake valve leak found and dealt with.

Dealing with slightly sticky fuel tank sensors in main and auxes.  Checked against SB, does not apply.  Removed one sensor and checked.

Complete inspection on all control systems complete.

Deflection of all control surfaces verified.

Electrical system diagrams complete and printed.

All required paperwork done.

Went through checklist multiple times.

All exterior placards installed.