Elevator Counterweight

I made the decision ages ago to make the elevator counterweights using tungsten instead of lead.  And I have been putting off making them.  The plan is to encase tungsten shot in epoxy.

I first tried to make the mold from wood.  Could not get the shape I wanted;  Abandoned that idea.

I want the weight as far forward as I can possibly make it, so the front needs to be curved.

FYI - tungsten is 1.7 times heavier than lead.  My theory is I would need less of it, could get the weight farther forward.  Overall lighter.

Weighted the arm of the elevator after paint.  I need 7.2 lbs of tungsten.

Mold version 2 is aluminum clecoed together.  I made it 3" tall - which will fit under the elevator tip fairing.  With tungsten only in the mold (as a test) it needs to be 2".

I applied packing tape to the inside of the mold (sides, bottom and back).  Waxed all the clecos.  Then a bead of clear silicone around the bottom.  Then a thin layer of epoxy on the inside of the mold, and let it dry.  My theory is this will seal up the mold so when the tungsten shot and epoxy go in it will not leak.

At this point I'm really wishing I had just made it out of lead.  Alas no... 

3.5 lbs is 1.59 KG.  The mold weights 410 grams, so the two together need to be 2 KG.  i overshot the mark slightly.

No leaks from the mold.

I added 3/4" of resin, then tungsten (there is actually a lead bullet in the bottom a friend gave me), and repeated until I got to the weight.  A bit more resin on top so everything is fully encased.

I am worried about tungsten falling out, which is why I put a thin coat of epoxy on everything first.  I may wrap the whole unit in fiberglass to ensure that doesnt happen.  Will see what it looks like when it comes out of the mold.

Bolts are all waxed.  Packing tape over the heads to stop leaks and keep them straight.  

Used West Systems.  Fast hardener on the skim coat, and slow on the main pour.  That should reduce any cracking.

Now the 24 hour wait...

Well it worked, and it fits under the fairing.

Now I need to make a 2nd one... already started.

2nd one done and test fit... slightly too long up front and will interfere with the elevator tip fairing.  So grinding in process.  Will have to fiberglass it back up.  Not a big deal.

First one drilled for the other two holes and dimpled.  All good.

Fiberglassed the second one up... not dry yet.  Cold in the hangar (well, relatively).

First one attached with bracket / captive fasteners.  My theory is (a) adds a bit of weight, and (b) you can check the bolts without taking the fairing off.

And the fairing fits too!

Am going to have to add some lead to the right side.  Just not heavy enough.  5 pieces of lead cut.  Will be darn close.

Cut, fit, fairings installed.  Just need to tighten down the screws.  Almost perfect balance (elevator pushrod disconnected in the pic... just hanging from the weights).

Done.  One list thing on the list.

Needed a dose of motivation... so start the engine!

The weather was reasonable (which means it wasn't raining) and needed a boost.  The engine would run, so today was the day.

Got oil pressure, so tried to start the engine.  Nope.  Would have helped if the fuel valve from the header tank was ON (it will be safetied open for flight).  Once that was found and the fuel system primed, she started right up.  

Check for leaks.  NONE!  But, fuel pressure indicator reads ZERO.  Need to check the sensor wiring.  The data is coming from the CANBUS, but there is nothing there.

Then the cowls went on.  Everything fits.

Started back up again.  Brought the RPM to 2200.  She wanted to GO.

Quick taxi... brakes need to be bled again.  Re and re'ed the park brake, and some fuel leaked out and air got in.

Successful day!

The endless list of tasks to make a project an airplane...

Steady progress.

5 years ago I build a crossover cable guide.  I remember I wanted to make another one, had the material, and now I need to get it finished.  So today was make a new one and get it installed.  I want to get all the rigging DONE.  Found half of the old one...

I had a minor issue in the process.  The sheathed cable for the tailwheel lock runs right through there, and didnt want it rubbing on the control cables.  Easy fix... adel clamp on the crossover to cage mount (not shown in the pic).

Passenger door hung.

My wife started cleaning... so much dust, etc.  Very grateful for the help.

Started removing the interior.  Need to add the 2nd pulley for the roll servo.  That is tomorrow's job with the interior out.

Need to rebuild the park brake valve (which leaks).  Done.  Sent for testing... no more leaking.

Need to add the window to door silpruf to the rear door.

The lower hinge on the baggage door would not fit in the cutout.  My hinge was lost at the paint shop, so the owner pulled the hinge off his damaged Sportsman... and it wouldnt fit.  Slight trimming, and now it does.  Needs to get repainted.

Fresh hardware (of correct size) in the pulley clusters.  Added 2nd pulley to the aileron forward pulleys for the autopilot servo.  Still need to cotter pin them.

Elevator counterweights.

Fuel flow test.  Did not go as planned.  Put 5 gallons in each main.  Header tank would not fill (sensors did not indicate it reached 1/3rd).  Suspect lack of venting.  After a lot of troubleshooting, closed the fuel selector and blew air into the header from the firewall to free up the check valves on the vent line.  That worked, but exposed a larger problem of stuck check valves.  Working on solution.

Put the aircraft on the big tires, on ramps / scales, and remove tailwheel to get the nose high.

Achieved 14.5 degrees, which is not enough.  But that is not the main issue.  Blocked vent line is the issue.

Weight and balance

Park brake valve.... leaked.  Removed, rebuilt, tested and reinstalled.  No leaks!  Installed... need to bleed brakes and add fluid... again.

Cowlings!  Anti chaff tape added to joggles.  Fine tuning the fasteners (Skybolt) for optimal fit.  Will be a couple iterations of on and off to get everything right.  But it looks GREAT.

Walk down memory lane... remembering what it used to look like 2.5 years ago.

Amazing what paint can do... but even paint wont fix something that's ugly to begin with.  Taking the time to make the cowl look right was so worth it.

Passed pitot static test, but cannot get the tailbeaconx into test mode.  Wifi will not connect... well, wifi not even seen.  AFS5600 is setting the tbx to standby, which should enable the wifi.

Fitting the skybolt fasteners on the cowl.  On off on off, adjust, etc.  Almost done.

Park brake done and works.  Need to bleed brakes.

Pushrod for anti servo tab.  Drying in place, needs correct fasteners once pull test complete.

TailbeaconX being sent in for service.  Cannot get it into configuration mode to test for pitot static.

406 ELT:  Beacon registry erroring out on the HEX ID programmed by Aircraft Spruce.  Beacon registry admin says it was reused... previous aircraft with that ID has been exported and ELT reprogrammed, so form filled out to fix.  That should do the trick.  Done and done.

Updated wing shot... 3 view.  Could not help myself.

So many little things to finish.

Reinstalled the recognition light on the belly.  No workie.  The pins are not lining up on the connector.  Bizzare... No changes were made.  I removed the pins from the connector and attached manually.  Still no work.

Engine mount rubbers have compressed.  I went to tighten the bolts and they moved.  Need to investigate.

All bolts tigthened and imagine that, the cowl lines up better.  I think that is a good thing.  I still think the front is sagging a bit - but the spinner lines up.  Thinking that problem is elsewhere.

Went to reinstall the belly strobe / recognition light.  This should have been a 5 minute job.  Bolts go in, no problem.  Hook up the connector - nothing.  No stroby stroby.  Check the pins... all OK.  Remove the pins and test with a 12V power supply, strobe works fine.  Check the airplane side of the wiring... nothing.  Cut everything apart and check the bare wires.  Nothing.  Take out the PFD and check the connector for 'aircraft rear'. All good.  Was about to take everything apart to check the wire connectivity and think ground... check the ground.  No ground... On the ACM there are very few grounds... and I did not hook that ring connector up to the chassis ground.  FIXED!  Had to rebuild the connector and pins, etc.... but it works and its BRIGHT.  Thank you AVEO!

Waiting for a parts shipment from Aircraft Spruce... that has the engine oil heater, which I will need operating this time of year.  Will be here tomorrow.