I got down to the airport really early this morning because I wanted to take care of a couple of things and get some flight time before heading back to Hollister to help Greg. I pulled the cowl and gave everything a thorough inspection. One of the things I found was that the oil filler tube could be rotated a little bit by hand. Since the safety wire hadn’t moved, I think the fiber washer just compressed a bit. I used a wrench to snug the tube back down and then redid the safety wire to keep it tight.
I also adjusted the high RPM stop on the governor 1 full turn to increase the maximum RPM a bit. I’ve only been seeing a little over 2600 RPM at the stop. Although I’ll likely have to adjust it further, I redid the safety wire to ensure this can’t move.
I buttoned everything back up and took off again. I figured I could get at least an hour of flight time before landing at Hollister again. I decided to shoot an instrument approach to get some more experience with the autopilot and interaction between the GTN and the SkyView. I loaded up the GPS 31 approach at CVH with the RUDNY transition and engaged the autopilot. I duplicated the approach waypoints in the SkyView since they don’t yet automatically stay in sync with the GTN (though this is coming). The GTN did turn anticipation and smoothly guided the autopilot onto the initial leg of the transition. I programmed an altitude step-down and commanded a 500 fpm descent. The autopilot turned smoothly to intercept the final approach course and held the descent rate rock solid. I broke off the approach a couple of miles out and climbed back up to 6,000 ft.
I headed over to the acro practice area and did a couple of rolls to warm up. I then tried a loop for the first time. The plane really builds speed fast on the down line, but pulling some G’s takes care of that nicely. Next, I tried a hammerhead on about an 80º upline to keep some positive G on the engine for oil pressure. The rudder is quite a bit more powerful than anything I’ve flown before, so the rotation at the top was crisp and quick.
Finally, I decided to do a few spins to learn how the plane recovers. The plan was to start with an incipient spin entry with an immediate recovery. I climbed up to 8,000 ft and positioned myself near the South County airport in case I needed it. I pulled the power smoothly back to idle and started slowing up. Right at the stall break, I fed in full left rudder and the plane rolled about 90º to the left and the engine stopped cold. The prop came to an immediate stop straight up. I had already initiated the spin recovery and I immediately rolled level and got the nose down into a glide.
One of the questions Dave Morss asked me to determine if I was ready for flight testing was how I reacted in an emergency situation. I’ve only had a couple of surprises in my years of flying, but I knew that I tend to remain calm and work the problem. When the prop stopped, my only reaction was to utter the word “interesting”. After establishing the glide, I hit the engine start button and got the propeller windmilling again, but the engine still wasn’t producing power. I still had the mixture pulled way out, so I opened the throttle to give the engine some more air. After a few seconds, the power came back smoothly. I climbed back up and decided to try again, but this time over Hollister since they have much bigger runways in case I couldn’t get the engine started again.
After arriving over the airport, I again pulled the power to idle and started to slow up. I slowed more gradually this time so that I could monitor the engine more closely. As the plane slowed, the engine RPM slowly dropped. When it got down to around 400 RPM, I knew something was wrong and I added power back. The engine stumbled a bit as the power came back up, but it ran smoothly again at around 75% power. I pulled back to around 40-50% power and the engine started running rough again. I brought the power back in and started examining the engine monitor more closely. My EGTs were down a bit, so I decided to try leaning the engine further and repeating the approach to stall. This time, the RPM held steady at about 700 RPM all the way through the stall break. I didn’t repeat the spin entry, but I feel comfortable now that the problem was simply an over rich mixture for the altitude.
I landed at Hollister to help Greg with his RV again. It took much longer than we expected, but we were able to wrap up all of the spar bolts and get the nuts torqued. The ailerons and flaps still need to be hooked up, but other than that, the plane looks pretty close to being ready for inspection.
I knew I was pretty close to empty on the left tank, but I wanted to run it dry on the flight back, so I left a little early to ensure I would have sufficient light. I ended up flying for nearly 20 minutes before the tank ran dry. I then switched to the right tank and landed at South County.