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N147EW is Airworthy! – 4 hrs

August 23, 2014 2 comments

Saturday Aug 23, 2014

After weeks of delays waiting for the FAA to approve the paperwork (and a vacation to see our new grandchild), N147EW had it’s airworthiness inspection today performed by DAR Matt Hlavac out of Ramona and was granted a special airworthiness certificate. In the inspection he found one issue with missing safety wire on the oil drain valve which I quickly remedied. Here is a photo of Matt going over the firewall forward section. He did a pretty thorough inspection based on a 7-page checklist.

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However, two weeks ago I did something that almost blew the inspection today. I decided to replace the lock nut on the fuel injection purge valve control arm. This is no big deal but when I put the new nut on I put the spherical bearing on the bottom of the control arm instead of on the top. I just didn’t notice that it was swapped. Here is an old photo of the control arm connection on the purge valve. The bearing is clearly on top of the arm.

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The problem is the nut physically runs into the steel fuel line if the bearing is mounted on the bottom of the control arm preventing the valve from fully going to the idle cut-off position. When I got into the airplane to start the engine today I did the standard procedure which is to put the purge valve into ICO position and run the fuel pump for 30 seconds to purge air out of the lines. Normally the purge valve shunts the fuel flow back to the right tank but because the valve was not fully closed it dumped a bunch of fuel right into the cylinders, totally flooding the engine. It simply would not fire up after several attempts.

Well this was completely atypical behavior based on the last four times I started the engine (before I changed the purge valve nut). We noticed fuel dripping from the filtered air box so I knew it was flooded. I decided to let things dry out for about 15 minutes. When I tried to start it the next time I pulled the mixture to idle cut-off and did not use the fuel pump. After about 8 blades it fired off and ran normally and I warmed it up a bit then ran a mag check for Mat. However, on shut down I pulled the purge valve knob to ICO but the engine kept running. That’s not supposed to happen. I shut it down with the mixture control and began to examine the purge valve control cable. That is when I found the problem with the bearing mounting. It took only a few minutes to fix it and then restart the engine and show Matt a normal shutdown. Crisis averted but it almost caused a failure of the inspection, a delay, and some money to get Matt back over here again for a recheck. It just shows you what a “minor” change can do if you don’t thoroughly check it out.

After that it was just the final paperwork and then Matt gave me the official airworthiness certificate. That is Matt on the right in this photo.

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Categories: Last 10 Percent

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

July 27, 2014 Leave a comment

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.

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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.

Categories: Last 10 Percent

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

July 13, 2014 Leave a comment

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.

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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.

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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.

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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.

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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.

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

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

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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.

Categories: Last 10 Percent

Engine Start – 4 hrs

July 6, 2014 Leave a comment

Sunday Jul 6, 2014

Successfully completed the first engine start yesterday.

 

Categories: Last 10 Percent

Flywheel Replaced – 5 hrs

June 28, 2014 Leave a comment

Saturday June 28, 2014

I installed the new flywheel this morning and got the prop re-installed. Here is a shot of the safety wire installed on the crush plate.

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And here it is with the spinner re-installed. Everything is now back to the way it was before the kickback.

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Here is another view of the starter and the new ring gear. I tested the starter to make sure it was still operating fine.

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As a check, I performed another “pull thru” test described by the Emagair installation manual to see if the timing was still set at top dead center (TDC). As a reminder, in this test the spark plugs are out but grounded to the engine and the prop is rotated by hand while observing the spark timing relative to the timing marks. However, this time I watched very carefully as the TDC mark slowly approached the hole in the starter. To my surprise the #1 spark plug fired about 1.5 teeth (about 3.5 degrees) ahead of TDC. I repeated this several times with the same results except the two P-Mags would sometimes fire at different times by as much as half a tooth (1.2 degrees) in spite of being set exactly the same. At this point I was thinking the P-Mags were just set advanced by 1.5 teeth and this was the probable cause of the kickback.

I decided to reset the timing to 1 tooth after TDC which is about 2.4 degrees retarded. So I rotated the prop to 1 tooth after the TDC timing mark and followed the P-Mag instructions to re-time them. After doing so, I performed the pull-thru test again and found that the #1 spark plug fired ½ tooth before TDC. What? There is that same 1.5 tooth offset advanced from the set point again.

So then I rotated the prop to 2.5 teeth after the TDC timing mark and retimed the P-Mags. This time I found that the #1 spark plug fired 1 tooth after TDC. Again, there is that 1.5 tooth offset.

I haven’t found anything in the P-Mag documentation about an offset between the set point and the spark during the “pull thru” test. Maybe this is an intentional timing offset to account for latency in the P-Mag electronics, or maybe there is a problem with my P-Mags. I don’t know. I plan to call Emagair on Monday to find out if this is normal or if it indicates a problem with the P-Mags. I was just not ready to try another restart today and risk damaging another ring gear until I can explain this behavior.

Here is another shot just to remind me how close she is to flying.

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Categories: Last 10 Percent

First Start and Weight and Balance – 17 hrs

June 22, 2014 Leave a comment

Sunday June 23, 2014

This post covers all the events of the last three days. On Friday I took a vacation day from work and went out to the airport to prep the aircraft for the first start. First I needed to pre-oil the engine and verify that it was developing good oil pressure (>25 psi). I removed the dessicant plugs and caps on the spark plugs on the spark plug holes and, following Lycoming’s recommendations I cranked the engine with the starter to watch for the oil pressure to rise. The first attempt at about 10 seconds showed nothing. A second attempt of 10 seconds again showed no pressure. The third time I cranked for more than 10 seconds and the pressure started to rise, reaching 39 psi before stabilizing. I let the starter cool a while and cranked it again and saw the pressure rise as before. OK, the engine is pre-oiled and I can have confidence that oil pressure will come up on start up.

Next I did an ignition check. This is simply connecting the spark plugs to the wires and grounding the bodies to the engine so you can see the spark. Then I turned the prop slowly by hand with the ignition turned on and verified that the spark plugs fired at the right time. All looked as it should be.

I installed the lower plugs in the engines and put the dessicant plugs back in the top holes. The rest of the time I was there was spent preparing for the engine start and weight and balance including installing the spinner and gear leg fairings and checking the settings in the Skyview setup.

On Saturday morning I had several friends and some family members turn out for the engine start attempt. Before everyone arrived I removed the dessicant plugs and pre-oiled the engine again since Lycoming says to do it within 3 hours of the first start. Then I installed the top spark plugs.

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I had two spotters, one on each side to watch for engine leaks or other trouble. I also had a friend armed with a fire extinguisher, just in case. Everything seemed to be ready. I had the instructions from Airflow Performance on how to do a cold start in hand. On the first try the engine fired after one or two turns and rev’ed up to about 1500 rpm then died. The same thing happened on the second attempt. Each time it ran 3 or 4 seconds then stopped. I was juggling the throttle to try to get it to idle but it would stop each time. Looking back I suspect it was the purge valve being at idle cut-off that was the problem. The engine would fire on the prime charge I added each time then die for lack of fuel flow. However, not realizing this at the time I tried several more attempts and on the sixth try I heard a clack and the prop stuttered. Immediately I stopped and one of my spotters took a look at the ring gear and found this.

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There was a kickback that took out six teeth. I’m not sure why or how this happened. For one thing, the Skytec NL starter has a shear pin that is supposed to shear to protect the ring gear. I don’t know why it didn’t shear. The starter looks fine and the pin does not seem to be sheared, although I did not try to crank it again. So this attempt to start the engine ended in disappointment and a damaged ring gear that I will have to figure out how to repair. I will call Aero Sport Power tomorrow to get their advice.

After that disappointment I finished installing everything on the airplane for weight and balance. Dave Prizio was scheduled to come by at 1:30 with his calibrated scales so I did not have time to mourn. Here is a shot of the airplane with everything on. This is the first time everything has been in flight condition (except the ring gear) at the same time. I also drained all the fuel out of the tanks.

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The weighing of the airplane only took a few minutes. We got it leveled up on the scales and the empty weights were 283 lbs on the nose gear, 415 on the right main, and 419 on the left main for a total of 1117 lbs. My c.g. calculations are all done on a spreadsheet and when I plugged the weights in later I was happy to find that I will be able to carry my wife and about 90 lbs of baggage and stay in c.g. range from take-off with full fuel to landing with no fuel. That is only 10 lbs less than the maximum allowed by Vans so I am happy considering  I have a very light prop which tends to push the c.g. aft and limit baggage. I guess that 20 lb crush plate on the prop was a good thing.

Today I went back to the airport and removed the cowling, crush plate, prop and flywheel. This is how forlorn the airplane looked after pulling the flywheel. I don’t know how yet but I have to get the ring gear replaced.  I’ll report more on the flywheel saga when I find out more.

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Categories: Last 10 Percent

Engine Prep for First Start – 2 hrs

June 15, 2014 Leave a comment

Sunday June 15, 2014

The picture below doesn’t tell much about what I did today but I snapped it as I was wrapping up so I posted it. To prepare for the first engine start I removed the engine sump plug and drained out all the preservative oil that has been keeping the engine in good order for the last year and a half plus. I removed the caps on the lower spark plug holes and turned the prop to push out the excess oil in the cylinders and then cleaned up all the drippings. I installed a Saf-Air quick-drain valve in place of the sump plug to make future oil changes easier and less messy.

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Then I added three quarts of mineral oil to the engine and waited a few minutes to let the oil settle, then checked the level on the dipstick. It measured 1.5 inch from end. This is what Aero Sport Power calls the 2 quart line. Then I added two more quarts of oil and after a few minutes of settling I checked the level on the dipstick again. It measured 4.0 inch from end.  This is the four quart line and this process is called calibrating the dip stick. I stopped there for today because I had an appointment for a Father’s Day call from my daughter so I will put in two more quarts next time to mark the six quart line. From that I will extrapolate to the eight quart line because I plan to start the engine with six quarts. No point filling the crankcase to the max capacity just to perform first start.

 

Categories: Last 10 Percent