Blast Tube Relocation

I continue to see posts in VansAirForce form about voltage regulators failing.  I have printed off the recommendations for testing the system if the regulator seems to be out.  In addition I have been thinking about a better way to cool the regulator.  My thoughts are that if the blast tube from the shroud on top of the engine were relocated to the cowl duct it might provide a cooler air supply.  Also, if the attachment to the cowl duct is made so it is a scoop in the airstream it may improve the cooling effect.  I may be all wet, but I decided to try it out.  

For the scoop I purchased a ½” – 45^o PVC slip fitting.  I removed the upper and lower cowlings.  I also disconnected the blast tube from the engine cooling shroud.  I inserted a plug and put RTV over it to seal the plug in place.

I drilled a hole in the top of the lower cowling duct tunnel about 6” in front of the damper.  I used JB Quick Weld to attach the slip fitting to the cowling.  I cut the end of the fitting into which the blast tube will fit with the band saw.  I cut the fitting so a screw clamp can compress the end of the fitting and hold the blast tube in place.  I put RTV around the end of the blast tube for a good seal to the fitting.  Now when the end of the tube is placed in the slip fitting and the clamp tightened it will not pull out.

I then mixed some epoxy resin, cut some fiberglass and laid up some fiberglass over the fitting to secure it to the cowling.  I put fiberglass on both the top and bottom of the fitting where it goes through the upper wall of the duct.  I will let the fiberglass cure overnight and reinstall the cowlings and connect the blast tube tomorrow.

Fly to Wendover

This morning I fueled the airplane with 10 gallons of premium and took off for Wendover.  I climbed to 5900’ as I departed the cross wind leg from runway 34.  As I flew over Magna I uploaded a flight plan and engaged the autopilot in the HSI & ALT mode.  As I flew over the Salt Air Resort I started my climb to 7500’.  As I arrived over the evaporation ponds north of Grantsville I climbed to 8500’.  I flew to Wendover over the Bonneville VOR.  I landed in Wendover and parked on the ramp. 

There were 4-other RV’s parked there.  An RV-7, an RV-6, and RV-8 and an RV-7A. There was also a Cessna 152 which had taken off from South Valley Regional about 20 minutes before I did.  I went inside and purchased an Historic Wendover Airfield cap.  I then got back into the RV-12 and flew back to South Valley Regional.  My trip out took 1.2 hours.  My flight back was 1.1 hours.  It was a great day to be in the air.  Upon my return and purchased another 10 gallons of fuel and put it in the tank.  As I finished fueling the Cessna 152 I followed to Wendover entered the pattern and landed.  It is a small world.  I hope to go up again next week.

Carburetor Float Buoyancy Test

Yesterday and today I worked on testing the carburetor floats as required by the ROTAX Service Bulletin – SB-912-065 R1.  I believe the serial number of my Rotax 912 ULS engine is out of the range of engines which need to be tested but I am complying with the test anyway.  Two weeks ago I ordered new choke gaskets for the carburetors.

Yesterday I removed the upper cowling.  I also prepared a 60 ml syringe by attaching a section of ¼” hose to the end.  I safety wired the hose to the syringe.  Today I modified a section of oil spout from an oil bottle to make a fitting which will go into the port on the carburetor.  I then moved the airplane out onto the apron and closed the hangar doors.  I started the engine and let it run for 2-minutes to ensure the carburetors were full of fuel.  I pushed the airplane back inside and proceeded to perform the test on the left carburetor.  I removed the choke spring and vent tube.  I removed the 4-screws holding the choke assemble to the side of the carburetor.  Using the syringe containing 60 ml of fuel I injected fuel into the lower port until it began coming out of the vent tube.  It took 25 ml’s of fuel.  The range of fuel volume for filling the float chamber is  23- 40 mls.  Any amount less or more indicates a problem.  The left carburetor is acceptable.  I reinstalled the choke assembly, vent tube and spring.  I then repeated the process on the right carburetor.

Both the left and right carburetors are acceptable.  They both required 25 mls of fuel to fill the float chambers. After putting everything back together including the upper cowling and putting the 5-gallons of gasoline I purchased into the tank I decided to go up for a test flight.  It was a beautiful day for the 7^th of January.  The temperature was 54^o F and the winds were light out of the south.  I took off on runway 16 and made 4-touch-and-goes.  The engine continues to run great!  I landed and put everything away.  I brought the engine log book home and made an entry certifying that Rotax SB-912-065 R1 has been complied with.

Good News To Report

The cable swivels arrived in the mail yesterday afternoon.  I went out to the hangar this morning and installed them.  The control arm on the oil shutter was thin enough that the swivel installed with only drilling a hole.  I cut the control wire to the right length and installed the swivel.  I have the controls arranged so with the control knobs pushed all of the way in the oil shutter and duct damper door are open.  

Pulling the 'OIL' control knob less than an inch closes the shutter.  I then installed the swivel on the air duct damper.  It took a little more work.  The material I used for the control arm was too thick to allow the swivel to turn.  I removed the arm and put it in my bench vise.  I used my Vixon file to reduce the tickness of a section of the control arm.  I deburred the arm with my Scotch Brite wheel and drilled a hole.   I reinstalled the arm and installed the swivel.  By pulling the 'AIR' control knob about 1-3/4” it closes the damper door.  I reinstalled the top cowling and finished installing the screws on the lower cowling.  I then pulled the  airplane out of the hangar and went up for a test flight.  To my joy and satisfaction as soon as I started the engine and closed the oil shutter the oil temp began to rise.  I finished buckling in and started to taxi to the end of the runway.  To my amazement, by the time I arrived at the end of runway 34 the oil temp was at 124^o.  It started at 40^o.  About half way to the runway I closed the air duct damper door.  I think that also helped to raise the oil temperature.  I took off and flew for 0.8 hours.  With minor adjustments to the shutter and damper door the oil and head temperatures were right where they should be.  The OAT was -2^o C.  I am pleased with the results.

Oil Shutter and Radiator Damper

This morning I went to the hangar and worked on the oil shutter and radiator damper modification.  I started by shortening the top pivot shaft on the damper door.  I also reduced the length of the arm on the damper control.  I then fabricated a mounting angle for the controls.  I painted the angle black and mounted it below the master switch module under the instrument shelf.  

I also drilled two holes in the firewall next to the brake fluid resivour and installed some grommets for the control cables to pass through.  I installed the lower cowl and determined a path for a section of 3/8” tubing to pass through in the cooling duct.  I installed the duct with Adel clamps.  I also installed a section of tubing through the firewall for the radiator shutter control to pass through.  I installed the tubing and the control cables. 

I also labeled the control knobs.  With the controls pushed in the oil shutter and radiator damper and both open.  By pulling the control knobs the shutter and damper close.  I put some high temp red RVT over the grommets and controls cables where they penetrate the firewall.  I will install the control wire swivel connections tomorrow if they come in the mail today.