(Cross posted from the blog)
As crappy as yesterday was in terms of operating and diagnosing the performance of a new airplane, today was much different as some of the classiest people on Planet RV stepped forward with great assistance.
Unbeknownst to me, Stein Bruch stopped by the hangar -- did I mention he's letting me use his hangar during Phase 1 testing? -- and gave the plane a pretty complete onceover. He reported that the left magneto is fine, thought the plane was well built, and identified a few areas that might contribute to the heavy wing Tom Berge noted on the test flight a week ago. One was a twist in the elevator alignment, and the other was a slight flap misalignment from left to right.
There's nothing to be done about the former, but the latter can be adjusted. But first I'll fly and see the extent to which the wing is heavy. I adjusted the aileron alignment the other day. I didn't notice a heavy wing on that first flight I made, but I was busy with other stuff.
Stein also noted -- correctly -- that the throttle cable is very stiff. We looked for kinks in it -- Stein stopped by on his way home from work, too -- but didn't find anything. So I'm going to try another cable. Question: Who's got another cable they'd like to let me try out?
As I was driving down to Lakeville, Alex Peterson called (actually, he called earlier and I called him back) while he was driving up north. He offered to fly down Monday evening and look at the RPM problem. But, he said, "you may not have a problem. The engine may not be performing as poorly as you think." Indeed, I do want to get the RPM indicator cross-checked for accuracy.
We also talked about the manifold pressure problem and he suspected a bad gauge and explained to me what it should be reading.
What was especially illuminating was when Alex talked about the noises I heard. He indicated that when the wind is blowing from a certain direction, he gets a "popping" sound from the air vent ports on the side of the fuselage. What he described fit perfectly with what I was hearing yesterday and probably wasn't backfiring at all.
Anyway, I tackled the manifold pressure problem first in an all day/night session this afternoon/tonight and found that I had failed to properly configure the engine monitor. I was supposed to enter some code that was on the Grand Rapids EIS 4000 manifold pressure box into the engine monitor. Once I did that, the MP indication on the monitor with the engine off read the barometric pressure indicated when I set the barometer to zero. That was a big one out of the way and means the manifold pressure problem I had was not an engine problem. Oh, I also blew out the manifold pressure lines and they were fine.
I also realized that the fuel pressure alarm that went off while climbing out of the pattern yesterday was not a fuel pressure alarm at all; it was a fuel flow alarm. I had configured the engine monitor to indicate an alarm whenever the fuel flow exceeded 19 gph. It was supposed to alert me to a leak in the system, but the FloScan module hasn't been calibrated yet so it was a worthless alarm. So, again, what I thought was an engine problem was not.
I took the filtered air box off and looked at the throttle plate to confirm that it opens complete. It does. Reinstalled the airbox and moved on.
I wanted to remove the fuel filter on the high pressure fuel pump but I didn't get around to it. However, I did repeat the fuel flow test by running the boost pump and pumping fuel into a five-gallon container at the fuel servo. It came out to about 43 gallons per hour, which pretty well matched the FloScan fuel flow indicator on the engine monitor. So all was good there. That number is actually better than it was when I ran a similar test a summer ago.
As far as the oil, I'm pretty sure now the oil was coming out of the breather tube, so I wiped up what I could and reinstalled the cowling, pulled the plane out, and hooked up my laptop to the engine monitor serial output, started the engine and went about seeing where things stood.
Here are some of the things I found, in no order of importance:
-- The Lightspeed tach reading and the manifold tach reading matched. I got about a 100 RPM drop when operating only on the mag. That's about 40 more than yesterday. I really should've leaned out the engine and cleaned some carbon, but I didn't. I got about a 20 RPM drop operating only on the the Lightspeed.
-- On runup, the static RPM reading was about 2020. About 120 more than I got yesterday,and about 90 less than what Tom Berge recorded last Sunday.
-- Fuel pressure was reading 36 with the boost pump on.
-- I took the runway and accelerated. I did not hear the infamous "noises" and developed 2105 indicated RPM (and increasing) when I pulled power when I reached 41 knots. It appeared to accelerate fine. It was a lovely night. If not for the operating limitations,I might have considered going flying.
-- On that run, EGTs were: 1143/1086/1062/1094
Cylinder temps were: 354/318/325/320
Outside air temperature: 80
Fuel flow: 12.9 GPH
Manifold pressure: 28.5
Fuel pressure: 36
Oil pressure: 81
Oil temp: 149
Total time from throttle forward to throttle back: 9 seconds
I taxied off the runway and back and tried it again. On the next run, I was at 2120 RPM when I shut down at 43 knots.
-- On that run, EGTs were: 1131/1085/1072/1103
Cylinder temps were: 346/302/313/315
Outside air temperature: 80
Fuel flow: 17.1 GPH
Manifold pressure: 28.4
Fuel pressure: 36
Oil pressure: 81
Oil temp: 164
Total time from throttle forward to throttle back: 10 seconds
During taxi back to the hangar:
Fuel flow: 5.7
Fuel pressure: 38 (left the boost pump on)
Manifold pressure: 13.3
It took 846 RPM to feed 14 volts (strobes, all lights, and all systems on)
I did try to use the GRT-recommended system of checking the RPM by trying to "freeze" the propeller at 600 RPM with a 60hz (or is it Mz, I forget) light in the background and I could not get it to do that at any number of RPM settings. I'll have to find an optical tachometer somewhere.
Total testing time: 21 minutes 33 seconds.
I did not notice any immediate pools of oil in the bottom cowling or around the breather tube.
I feel pretty good about these numbers. The static RPM is still a little low, but as I said, we need to doublecheck the tach readings.
If anyone wants the spreadsheet with all of the numbers, just holler.
