Transponder Test, Taxi Test, Fuel Gauge Calibration – 9 hrs

Sunday July 27, 2014

Another thing I needed to do before the airworthiness inspection is to have a transponder test performed by an FAA certified repair station. Since my airplane is equipped for day/night VRF flight I only needed a VFR test performed. Gerdes Aviation Services was recommended to me so I called Brain Gerdes and scheduled a test at my hangar. He has a mobile service that makes it convenient for guys like me who work during the week. He arrived at 9:00 AM and went to work setting up his equipment.

I had not given it a lot of thought before but I realized when he set up his air pumps to attach to the pitot static system that this could go badly if I had any leaks in the fittings.  Brain said since this was my first test he would perform most of the IFR check at no additional cost to make sure my system was not just reporting altitude correctly but also was leak free and measuring airspeed correctly. He ran into a problem when he tried to switch the transponder to ALT mode. The Dynon transponder would not switch from STBY mode. I almost panicked because I’m thinking wiring problems. We checked the system setup and remated the connector to the transponder. I also updated the transponder firmware. When I was about to give up I noticed that the hex code on the transponder setup page was all zeros. Brain immediately recognized that the hex code was the issue. I missed the instructions somehow to obtain and load that code into the Skyview EFIS. Brian quickly found the code on the FAA web site (see http://registry.faa.gov/aircraftinquiry), I entered it, and the transponder switched into ALT mode as it was supposed to. Moral of this story – no hex code, no ALT mode.

The actual test went really well. Brian said that my pitot static system had no significant leaks and would easily pass an IFR leak test. The altitude reporting of the Skyview ADAHRS/transponder was well within the accuracy requirements for VFR or IFR up to 20,000 feet except for my backup EFIS, the Trutrak Gemini, which was reporting 40 feet low but needs to be within 20 feet at sea level for IFR use. I will need to get it recalibrated if I upgrade to an IFR panel later. Airspeed measurement was accurate to within 1.5 or 2 kts all the way up to 200 kts for the Skyview and the Gemini.

All in all, the transponder test by Brain Gerdes was a very good experience. I would recommend his services to anyone.

After Brian left I pulled the airplane out of the hangar, put on the cowling, and started it up for a taxi test. The objectives were to check toe in/toe out and make sure it tracked straight, and to condition the brake pads which removes high spots and creates a layer of glazed material at the lining surface which improves brake holding power. I taxied down the aisle, west along the hangar row toward the end of the runway, right onto the main taxiway, back eastward to about mid field and right again to my hangar aisle. As I taxied I applied brake pressure at a fast idle to wear in the pads and create heat which builds the glaze. The airplane taxied well, although it felt different than the C-172s I am used to. I think the friction in the nose gear makes it steer differently. Plus the airplane is just lighter than I am used to. When I got back to my hangar the CHTs were up to about 375F and I reduced the throttle to low idle. When I pulled the throttle all the way out with light pressure it went to about 600 RPM and idled nicely. If I pulled firmly back on the throttle the RPM would drop down to about 550 and felt rough like it might die on me. As far as idle adjust goes this may be perfect. On final approach I want to be able to reduce RPM as low as possible without the risk of the engine dying. At 65 knots the windmill effect will increase the idle RPM slightly. 600-700 RPM would be perfect. Until I fly I won’t know for sure, but I am thinking the current idle setting will give me that if I don’t pull back hard on the throttle. I think I will leave it as is for now.

Today, I went back to the hangar with Denise to do the fuel gauge calibration. This is where the Dynon EFIS records the fuel sender voltage at known fuel levels and generates a calibration curve so the display reports the fuel in each tank accurately. One problem with the Vans resistive fuel senders is the floats reach the end of travel at about 19 gallons so they are not accurate above that. The calibration process is to start with an empty tank, start the Dynon calibration mode, enter 2 gallons at a time pressing the EFIS ADD button each time so it records the voltage at each level. You do this all the way up to full (21 gallons). Now this was a pain because I already had about 2 gallons in each tank so I had to drain the tanks completely into a 5 gallon container to begin the process. Then I started the calibration routine for the right tank to record empty as the first point, then I added 2 gallons from my container and pressed the ADD button, added 2 more gallons and pressed it again. To continue I called the mobile fuel truck to come over and fill the tank two gallons at a time as I pressed the ADD button at each increment. That was the easy part which completed the calibration for the right tank. The Dynon figured out that the fuel sender pegged out at 19 gallons because the display showed 19+ gallons instead of 21 which is the Vans published number.

Then I used the fuel pump to drain two gallons at a time from the right tank into a container which I then poured into the left tank to calibrate that fuel gauge. Denise was helping me so the process went faster than it otherwise would have, but it was a pain nonetheless. As we drained the right tank the calibrated right fuel gauge accurately tracked the level as we removed 2 gallons at a time. After completely draining the right tank, the left tank was full and Skyview completed the calibration routine. Both gauges should be pretty accurate now. I will check them with the totalizer in the future.

Next time I will transfer 10 gallons back from the left tank to the right tank so I will have half full tanks on both sides for the first flight.

Moved to New Hangar, 2nd Engine Run – 4.5 hrs

Sunday July 13, 2014

I’ve had a dust problem in my hangar, except most of it is not common dust, it is man-made. Next door is a paint shop and there are gaps between the walls and the ceiling that allow sanding dust to drift over into my hanger. Here is a photo of the right wing of the RV-7A after one week in the hangar. You can even tell the color of the surface being sanded by the color of the dust. One day it may be dark grey, this last week it was mostly white.

Here is a view of the canopy also. I told the hangar management at the airport about it and they told me I could move to another hangar across the aisle. In addition to being cleaner, that hangar faces west and will be cooler during the summer mornings when I am typically out there, so that is another plus.

So yesterday Denise and I moved everything to the new hangar. It was only about 100 feet away so I just pulled the airplane down with a tow bar. We also took a little time to organized things better. Here is the airplane in the new hangar. All the hangars are the same size so no difference there.

This is the right side where we set up the work bench (recycled Vans shipping crate lumber) and the mini refrigerator where we keep cold water and treats.

Denise set up a “living room” area on the left side. Okay, I’m going to go with her on this for the sake harmony.

The back of the hangar has lots of room for storage. This is the left side.

And this is the right side. Plenty of room to maneuver without getting cramped.

After that I decided to do another short test run of the engine. Last week I was so excited to get the engine started (after my ring gear issue) that I only ran the engine at about 1000 rpm for a while and monitored the instruments (pressures, temperatures, etc.). This time I wanted to do a mag check on both sides and run the engine to full static rpm. So I pulled the airplane out of the hangar, pointed it down the aisle and put the wheel chocks in place. I set up my GoPro in the cockpit to film this time using my NFlightCam cockpit kit with audio cable that hooks up to the aircraft intercom.

The engine ran even better than I remembered last time. I let it warm up a couple of minutes and leaned it a little since the density altitude was about 2400 feet then rev’d up to 1700 rpm for a mag check. The rpm drop on each side was about 50 rpm which is just about ideal.  Then I reduced the rpm to see how low it would idle. It went down to about 600 rpm before it felt like it was about to die, which I did not let it do. The idle is set a little low right now because it will die if I pull the throttle all the way out. But 600 rpm is lower than I expected to be able to go with this light composite prop. It would idle smoothly in the 700-800 rpm range.

Then I rev’d the engine back up to try to get to full static takeoff rpm. I was watching the tachometer climb above 2000 rpm when the airplane began to jump over the wheel chocks while I was standing on the brakes so I cut the throttle immediately. It only went forward about a foot but it really wants to go. 180 hp in this light airplane is a lot of thrust. I’m hoping to see about 2200 rpm at takeoff but I’ll have to wait for the first flight to see what I get. Even 2000 rpm would get me off easily at KAJO.

Unfortunately for this experiment the Garmin intercom filters out all the engine noise with the NFlightCam audio cable so the GoPro video is kinda boring without being able to hear the engine. That feature will be nice later when I am filming in-flight video but in this case I wanted to hear the engine.

Engine Start – 4 hrs

Sunday Jul 6, 2014

Successfully completed the first engine start yesterday.