flion
Well Known Member
This has been an exhilarating month. Since being released from a heavy teaching load thanks to the CoV-2 strain, I've finally been able to get to the panel change on my RV-6A and have accomplished more in the past month than in the previous two years. In fact, I have finished the work, done the G3X calibrations, and completed a condition inspection so the aircraft is ready to fly. But I'm not, and I'll explain the symptoms that convince me that I need to cool off a bit before taking to the air.
Two days ago, I finished connecting all the FWF sensors. The CHTs and EGTs had previously been connected and tested, as has been all other peripherals to the G3X system. Everything had been flawless so I was not expecting problems but a test showed that the oil temp sensor was not reading. I checked the connections - all good. It was the same sensor that had been there before and looked identical to the one shipped with the G3X, but I was tired so I figured I'd come back the next morning and try the new sensor. Fortunately, overnight my brain reengaged, so before swapping the sensors out, I checked the configuration and tried changing from the default to a K-type sensor and magically it worked. Ok, not too serious, but it's the beginning of the curve.
The rest of that day, I put the tank/wing root fairings back on, since there were no signs of leaks other than a dripping sump (replaced O-ring, problem fixed), buttoned everything up, and pulled it out to try an engine start. About when it should have started I got two backfires in succession and then the prop wouldn't turn. With not enough battery, I put it on the charger overnight. My guess (wrong) was that I had flooded it and didn't have enough battery to try a hot start procedure. Trying again in the morning again gave me backfires and eventually the prop would not turn, until I attached a boost battery - but you could see it straining at times. Now, finally, the brain wakes up - it acts like the lightspeed ignitions are out of phase. I had tested those before, but I would pull the top plugs to test again.
The procedure is to rotate the prop rapidly by hand back and forth across TDC. The plug wires are removed from the coils (and the top plugs are out), so there is no danger of starting but you will see a spark jump the coil outputs each time the prop moves past TDC in the right direction. Which coil sparks for #1 TDC also tells you which coil to connect #1 and #2 cylinders to. Repeat 180 degrees off to spark the other coil for a 4-cylinder engine. But, as I prepared to test the phase, the brain finally fully wakes up and reminds me that the marks on the front of the flywheel are different than those on the back. Yep, I had connected them out of phase but it was an easy fix to swap the coil connections at the lightspeed boxes.
After that, the engine started normally and I did a run-up and tested the engine and prop controls. Then I re-buttoned up the cowling, restarted, and taxied out to the compass rose to do the magnetometer calibrations. The magnetic interference check was no problem, so I restarted to do the compass swing, but there was too much airframe movement with the engine running so I shut down and called a friend to help run the calibration while I used my towbar to pull the plane around the circle. No problems and afterward I went to start the engine to taxi back but no joy. Even the hot start procedure did nothing.
Rather than run the battery down again, I pulled the plane back to the hangar with the towbar (fortunately not far) and put it back on the charger. When asked if I was going to fly it, I declined, preferring to wait until tomorrow when (I hoped) the engine would be in cool start condition again. It was not until I was on the way home when I realized what the trouble had been. With my mind on all the other things involved in completing the condition inspection, instrument calibrations, etc., I had forgotten to push the fuel purge control back in (AFP injection). My mind was clearly not 'flight ready' and I was not using my checklists or thinking my procedures through on something 'as simple as taxiing back to the hangar.'
So, beware tiredness, excitement, or other conditions that can lead to mistakes, even while building, or maintaining, as opposed to flying. We've all heard stories of people who left off a cap or forgot to safety a fastener or some such but we tend to think 'not me!' I did not realize how far away from flight ready I was until I reflected on the events above. But now I'm aware and I'm pulling out my POH to review procedures. More importantly, I will have the checklists in hand before I operate the aircraft again, rather than cavalierly assuming I know them well enough for ground operations. If you've had a bad building or flying day, maybe you should rethink your headspace, too.
Two days ago, I finished connecting all the FWF sensors. The CHTs and EGTs had previously been connected and tested, as has been all other peripherals to the G3X system. Everything had been flawless so I was not expecting problems but a test showed that the oil temp sensor was not reading. I checked the connections - all good. It was the same sensor that had been there before and looked identical to the one shipped with the G3X, but I was tired so I figured I'd come back the next morning and try the new sensor. Fortunately, overnight my brain reengaged, so before swapping the sensors out, I checked the configuration and tried changing from the default to a K-type sensor and magically it worked. Ok, not too serious, but it's the beginning of the curve.
The rest of that day, I put the tank/wing root fairings back on, since there were no signs of leaks other than a dripping sump (replaced O-ring, problem fixed), buttoned everything up, and pulled it out to try an engine start. About when it should have started I got two backfires in succession and then the prop wouldn't turn. With not enough battery, I put it on the charger overnight. My guess (wrong) was that I had flooded it and didn't have enough battery to try a hot start procedure. Trying again in the morning again gave me backfires and eventually the prop would not turn, until I attached a boost battery - but you could see it straining at times. Now, finally, the brain wakes up - it acts like the lightspeed ignitions are out of phase. I had tested those before, but I would pull the top plugs to test again.
The procedure is to rotate the prop rapidly by hand back and forth across TDC. The plug wires are removed from the coils (and the top plugs are out), so there is no danger of starting but you will see a spark jump the coil outputs each time the prop moves past TDC in the right direction. Which coil sparks for #1 TDC also tells you which coil to connect #1 and #2 cylinders to. Repeat 180 degrees off to spark the other coil for a 4-cylinder engine. But, as I prepared to test the phase, the brain finally fully wakes up and reminds me that the marks on the front of the flywheel are different than those on the back. Yep, I had connected them out of phase but it was an easy fix to swap the coil connections at the lightspeed boxes.
After that, the engine started normally and I did a run-up and tested the engine and prop controls. Then I re-buttoned up the cowling, restarted, and taxied out to the compass rose to do the magnetometer calibrations. The magnetic interference check was no problem, so I restarted to do the compass swing, but there was too much airframe movement with the engine running so I shut down and called a friend to help run the calibration while I used my towbar to pull the plane around the circle. No problems and afterward I went to start the engine to taxi back but no joy. Even the hot start procedure did nothing.
Rather than run the battery down again, I pulled the plane back to the hangar with the towbar (fortunately not far) and put it back on the charger. When asked if I was going to fly it, I declined, preferring to wait until tomorrow when (I hoped) the engine would be in cool start condition again. It was not until I was on the way home when I realized what the trouble had been. With my mind on all the other things involved in completing the condition inspection, instrument calibrations, etc., I had forgotten to push the fuel purge control back in (AFP injection). My mind was clearly not 'flight ready' and I was not using my checklists or thinking my procedures through on something 'as simple as taxiing back to the hangar.'
So, beware tiredness, excitement, or other conditions that can lead to mistakes, even while building, or maintaining, as opposed to flying. We've all heard stories of people who left off a cap or forgot to safety a fastener or some such but we tend to think 'not me!' I did not realize how far away from flight ready I was until I reflected on the events above. But now I'm aware and I'm pulling out my POH to review procedures. More importantly, I will have the checklists in hand before I operate the aircraft again, rather than cavalierly assuming I know them well enough for ground operations. If you've had a bad building or flying day, maybe you should rethink your headspace, too.
