Stabilator Tips

Santa Claus was kind enough to deliver some genuine Texas-made stabilator tips under our Christmas tree, so I just had to install them with the abundance of free time during the holidays.

First step was to temporarily fit the mounting bracket to the stabilator end rib and mark the bend line on each of the bracket's 10 tabs.  The objective was to have the tab lay 1/8 inch below the surface to allow for the thickness of a J-nut and the tip itself.  After the tabs were marked and bent, the unit was prepped and primed as shown below.

Next, the tips had to be marked for alignment with the pre-drilled holes in the mounting bracket tabs.  Careful measurement was required and a 1/16 inch hole was drilled at each of the tab locations into the tip.  The blue masking tape allowed for better visibility of the marks.

The end rib of the left stabilator is shown below, with the 5 holes to be used for fastening of the bracket.

I added another 8 rivets in strategic locations in an attempt to minimize any potential flexing of the bracket with the end rib.

Finally, the holes in the tip were drilled out to 1/8 inch and were fastened to the tabs of the mounting bracket with number 6 screws.  I managed to get a perfect match between the tip's edge and the end rib of the stabilator...on the underside!!!!  The top side, unfortunately, is not a great match and features a 1/16 to almost 1/8 inch gap along the length - just enough to be noticeable.  Sometimes the seemingly easiest tasks are those that turn out to be the most frustrating.  At least I get another shot at the right tip.  I'll try to get that one perfect.

Apparently I did not apply enough upward pressure on the tip (my wife's analysis) as I was measuring/marking the hole locations on the tip.  She's probably right.

Wing Tanks! (Fuselage Components)

Yes, it's true - there will be no box fuselage fuel tank in my RV-12.  I believe Viking has a viable and preferable alternative.  It consists of a small standpipe in the corner of the baggage compartment which interconnects to 4 tube tanks, resting in the lightening holes on either side of the main spar of each wing.

The process begins with removal of the box tank and then cutting a hole in the baggage compartment floor, designated by the bracket shown in the second picture below.

Aforementioned bracket cleco'd into place from 3 drilled out rivets in the baggage floor.  The standpipe is temporarily jigged into place on the longeron, where it will call home for the foreseeable future.  The bung at the top of the standpipe will be for a vent.

The standpipe as it projects below the baggage floor.

The third bung on the right is for the engine fuel feed line.  A large finger strainer is screwed and sealed into place.  Later, the supply line itself will be screwed and sealed into the female threads of the finger strainer as it runs to the fuselage center line where it will intercept the existing supply line.
The bung of the end cap of the standpipe will be for a drain sump valve.

Here is a potential mockup of the right wing's supply line fitting.  I don't yet know if this is feasible as I have not built the wings and do not know if there is 1.5+ inches of clearance between the fuselage side and the root wing rib.

Closeup shot of the nipple, coupler and elbow fitted together for the geometry imposed by the standpipe and bung.

Loosely screwed together to see if I'm in the ballpark for clearance between the fuselage and wing root.  The answer is still a long way off.  I have to build the wings first!

Shown below is the termination of the engine supply line, that will run from the lowest bung of the standpipe.

 A shot of the left wing's supply line as it runs from the standpipe.  The 3/8 inch aluminum tubing clears the top of the lightening holes by 1/16 - 1/8 inches.  The horizontal white lines are actually strings that will be used to route control cables for the rudder and stabilator.

 The photo below shows the three lines (from bottom to top: engine supply, engine return and left wing supply) from the standpipe, running toward the center line of the fuselage.

Another view from slightly further aft (near the exit of the right flaperon torque tube), looking forward.

 More to come, so stay tuned.

 

Upgrade to the Upgraded Flywheel

The Viking factory reported some incidents of ring gear slippage on the new flywheel assembly that I recently upgraded to.  The recommended remedy was to remove the unit and separate the ring gear from the flywheel and make some changes.

So, off to drain and then remove the radiator, then the PSRU and finally the flywheel/ring gear assembly.  The remedy begins by bonding the ring gear to the flywheel with green Loctite.  After some research, I resolved to use Loctite 620 which is the most viscous and highest shear strength of the green Loctite family for this application.  But alas, I'm getting ahead of myself.

The ring gear had to be separated from the flywheel first and then the two components cleaned thoroughly with acetone prior to bonding with Loctite.  The first two photos below show the nice bead of Loctite that resulted from dropping the heat soaked (to 350 deg F) ring gear down onto the flywheel.

The final step of the process involved the replacement of the smaller washers with some AN970-3 washers that had a larger outside diameter for greater surface area contact.  I also used some red Loctite on the nuts, which are also secured with lock washers.  See below.

Now it was time to bolt the flywheel back onto the engine, after scrubbing the 6 bolt's threads clear of the previously used blue Loctite.  As usual the bolts were torqued back down to 80 foot pounds per Viking and secured with blue Loctite again.

I like to refer to the next shot as the "sacred geometry".  The rubber isolators have to be oriented as shown with the factory sketch ON the flywheel, below.

The next major step of the process involves aligning the PSRU studs of the spider gear and driveshaft to the rubber isolators and the crack bushing.  The business side of the PSRU as it is readied for installation.

PSRU in place.

Oil line from the engine galley plumbed into the top of the PSRU.

Then the gearbox temp probe is installed too.

The last major step in the process is to plumb the gearbox oil discharge line from the former location of the siteglass back to the oil tank.

It takes careful orientation of two elbows at the site glass location to negotiate the path around the coolant tube as shown below.  After running out of room with the cowling in my original configuration, I had to re-route the oil line aft of the coolant tube.  It worked out okay, but I was really sweating it to get to this perfect arrangement.  Four pictures to show the various angles of this tightly configured area.

It looks like I'm back to where I started again....hopefully that is the final install of the upgraded flywheel.

Forward Progress Resumes!

Upgraded parts arrived from the factory in very short order, thanks Jan.


First task was to reinstall the upgraded flywheel and the PSRU.  First shot below is the backside of the PSRU with the newly pressed on spider gear onto the splined shaft.  Also seen below is the new aluminum bushing that replaces the pilot bearing.

The next shot illustrates the first of 2 elbows that begin installation in the former location of the site glass of the PSRU.  These fittings will connect to the oil tank return line.

About to press in, or in my case, tap in the pilot bushing.

Another shot of the thickness of the bushing.

Home sweet home for the foreseeable future.

The upgraded flywheel and the rubber doughnuts.  Note the unthreaded studs on the flywheel upon which the rubbers will mount.  No more bolts and nuts needed to secure them to the drivetrain.

Doughnuts mounted to the flywheel, awaiting installation on the crank pulley.

 Finger tightening the 6 flywheel bolts after a generous coating of blue loctite.

Torque wrench and requisite elbow grease liberally applied.

Rubber doughnuts hung in place in the correct orientation as designated by the hand drawn image (from the factory) on the flywheel.  It will be hard to screw this up.

Now carefully begin the alignment process of the splined driveshaft into the pilot bushing and the 4 aluminum standoffs/bolts into their respective holes on the engine.

It actually fit quite easily and there was no real force required to set it into place.  Another liberal dose of elbow grease and the torque wrench finished off this important task.

Now, I wanted to continue to plumb the PSRU for its engine oil circulation, so the first of 2 flared steel fittings was threaded into place with sealant.  This was the original location of the gearbox temperature sender, so I removed it and relocated it the adjacent hole.  The flexible steel oil circulation line was pretty short and I needed every bit of help to span the distance from the oil galley port on the engine to the PSRU.  You can just see the terminating end of the flexible steel oil line on the left side of the picture.

In order to obtain good access to the oil galley port, it was necessary to remove the intake manifold which requires a ball hex driver as shown below by the extreme angled approach to the allen bolt.

Once the manifold was removed, the target was much easier to locate and a trial fit of the flared fitting with the other end of the oil line.  Again, the flared fitting was tightened into the galley port with a liberal amount of thread sealer.

Next, the manifold was reinstalled paying careful attention to the clearance of the steel oil line.  There could not have been any less clearance between one of the pipes of the intake and the terminus of the oil line - literally 1 or 2 millimeters.

 Another view of the oil galley end of the line as it runs to the PSRU.  That is the starter that the oil line is passing over enroute to the PSRU.

And finally, a complete shot of the oil line running from the engine's galley to the PSRU.  Note the adele clamp securing the line from interference with the ring gear of the flywheel.

Upgraded oil tank installation is next up.  After applying a thin coat of the Right Stuff to the top of the oil tank, where it mounts to the block, it was necessary to get a long allen driver with extensions to reach the mounting holes.  I believe there were 12 M6 metric bolts that had to be installed and torqued to 35 inch-pounds torque.  Lots of overhead reaching with delicate positioning - not too much fun....but got her done.

This shot shows the bottom of the oil tank and looking up into the lid, where the bolts are securing the assembly to the block.

The blue return line from the PSRU had to be connected to its bung, threaded with a barbed fitting.  Also seen in the background is the silver steel teflon oil supply line which runs from the block to the top of the oil tank.

Last task for this installment involved glassing up another oil cooler duct.  I used a couple of tin cans, taped end to end for my mold.  Covered them with duct tape and then slathered them with car wax.  Three or four layers of glass cloth should do the trick.  Shown below is the beginning of the mold removal process, which involves carefully destroying the tin cans.  It was not as difficult as it might look.  After some initial crumpling, it was easy enough to work a thin bladed screwdriver around the edge and bend the can inward, so it could be removed.

The prize!