I went out to the hangar early today, intending to do a bunch of work, then go flying. I spent a bit of time modifying some hardware to allow connecting the hangar plane mover to the tailwheel, as one of my hangar mates finds the aircraft hard to move around. I then installed a canopy air dam and weather stripping, in an attempt to stop the drafts that come by the back end of the canopy skirt. I also reinstalled some of the cockpit sidewall panels, as Terry had sewn on some Velcro strips to hold them in place.

Then I attacked moving the fuel flow transducer to get it between the engine-driven fuel pump and the fuel injection servo. That all went fairly well, but I decided that I should add a heat shield and some firesleeve before I fly. I’ve got firesleeve, at home, of course, but need to order a heat shield. So, no flight today. :( Hopefully I can get a heat shield here this week.

I got a bit of free time to head to the hangar Wednesday last week, and attacked the CHT indication problem. I reseated the connectors between the CHT #1 probe and the extension wire that goes to the Engine Indication System. Then I rechecked CHT #1 and #3 in boiling water. Now both were showing the same temperature - about 10 deg F too low. Now that CHT #1 seems to have the same errors as the others again, it will be interesting to see how it compares to the other cylinders next time I get flying.

While I was at the hangar, I made a cardboard template of the area at the rear of the canopy frame. Terry will use the template to make a removable cloth screen that will be part of a scheme to hopefully stop the air drafts coming from under the canopy skirt. Hopefully we can try it out this coming weekend.

I pulled the passenger seat cushions out and brought them home, so I could install a heated seat kit. But, I learned that the leather seat covers are glued to the foam cushion. So, it will not be possible to install the heated seat kit. Terry has a 12v electric blanket that a friend gave her - we will try that next time we go flying.

I was on the road from Thursday until late this afternoon, so nothing got done on the aircraft. I did take the time for an editorial cleanup on the POH.

It’s been a good RV weekend. Yesterday, I took one of my coworkers for a short local flight. It was the first time he had been upside down for a good number of years. After we landed, I plugged the engine preheat into a timer, so it would start its magic at 7 AM on Sunday, as it was supposed to get well below freezing overnight.

Today, Terry and I zipped out to the airport and launched for Lindsay to have lunch. The engine was nicely warmed up by the Reiff preheater, and we wasted no time in getting airborne. It was a beautiful day to go flying, and we took about 50 minutes each way (126 nm), and had a very nice lunch. It was the first time I had been more than 25 nm from Smiths Falls, and the first time we had done anything “useful” with the aircraft. The main point of the exercise was to get a slightly longer flight, so Terry could see if there were any more issues I needed to address before we do longer flights.

She confirmed that there is a draft coming up around the rear seat stick. I’ll try putting some vinyl tape where the wing spars go into the centre section, and I’ll get a stick boot made. She confirmed my suspicion that there is a draft from the rear end of the canopy skirt. I have a plan for that, and I’ll report once I’ve had a chance to try it out. I’m also going to run a 2” SCAT tube from the hot air outlet on the back side of the front baggage aft wall to route it to the rear seat. And, I’ve got a line on a heated seat kit that I will try to put in the rear seat.

We forgot the camera, so no pictures.

I've done some thinking about this, and I wonder if the low CHT #1 indication could possibly be due to excessive resistance somewhere between the CHT probe and the engine monitor. Each CHT probe is connected to about 18" of metal shielded cable, then each of the two wires per probe has spade connectors that connect them to extension wires that go to the engine monitor. The CHT probes are thermocouples, and if there is a high resistance at one of those spade connections, it could lead to the engine monitor sensing a lower voltage than the CHT probe is actually creating.

Next time I have the cowlings off, I will inspect and reseat the spade connectors for the #1 cylinder, then I'll check it in boiling water again. If that doesn't do it, I'll disconnect the #1 and #3 CHT probes at their spade connectors and trade them, and check with boiling water again. It'll be useful to see if the problem follows the probe, or if it stays on the #1 cylinder.

If the problem stays with the probe, I probably need to replace it. If the problem stays on the #1 cylinder, I'll pull the connector at the EIS and check for pins that aren't fully inserted. Pulling and reseating the connector should clean off any corrosion too. Next, I'll swap #1 CHT with another cylinder by moving the pins in the connector, to take all the wiring out of the picture. if the problem stays on the #1 cylinder after all that, I'll contact Grand Rapids, as I almost certainly have a failed engine monitor.

I went out to the hangar this afternoon, pulled the cowling, then rigged up a metal can hanging from a step ladder to boil some water. Three of the four CHTs went to 202±1°F when the water was boiling furiously. CHT 1, the one that reads 50 - 60°F lower than the others in flight, went to 178°F. I looked at the wiring, and did find that one of the connectors at the back of the EIS 4000 was a bit loose. I tightened it and repeated the CHT checks, but there was no real change.

So, it looks like one third to one half of the low CHT indication is caused by some sort of instrumentation error. I need to sort that out before I make any more baffling changes. I removed the one change I had made, as I no longer trust the CHT indication on #1 cylinder, and don’t want to do anything that could cause it to go too high.

I had checked the CHT calibration using boiling water back in July 2006. At that time they all indicated about 3°F too low. Today the ambient temperature was just above freezing, and three of the four CHTs read about 10°F too low. The CHT indications use a reference junction inside the EIS 4000, and there is perhaps some sort of temperature sensitivity to it. In flight, I would have had the cockpit heat ON, and the cockpit temperature would hopefully have warmed up, so I suspect the error in the CHT would have been less. The atmospheric pressure was high today, so the pressure altitude was about 100 ft. Thus the boiling point of the water would have been 212°F.

I’m not sure what could be causing the low CHT #1 indication. I’ll contact Grand Rapids Technologies to get advice on what to do next.

I checked the weather forecast this morning, and it was pretty shaky - lots of low cloud and rain showers. But, this afternoon things turned out to be much better than expected, so Terry and I headed for the airport. There were rain showers from the next weather system approaching from the west, so we only did a short 20 minute flight. The main aim was to get Terry’s comments on seating position, find any drafts in the rear seat area, and identify any other major issues that needed sorting out before we planned any longer flights.

After 11 years of building, and a year long flight test phase, Terry was more than ready to get up in the RV-8. She found the seat cushion from D.J. Lauritsen of Cleaveland Tools to be very comfortable, and the rear seat riser I added was at a suitable height and angle (earlier info - 1, 2 and 3). There is some air coming in around the rear seat stick - I plan to make a flexible boot to seal that area. The fuzzy Velcro I put under the canopy fairing to stop it from buzzing against the fuselage seems to be doing a good job at sealing any drafts from getting in - I suspect that finding might be overturned once the weather turns colder.

If the weather turns out to be better than forecast tomorrow morning, we’ll head for the Kingston Flying Club Fly-In Breakfast.

I dropped the paperwork off at the Transport Canada regional office on Monday, so they could review it and issue me a Special Certificate of Airworthiness that didn’t have the “No Passengers” or “Remain within 25 nm of Smiths Falls airport” restrictions. The new paperwork was ready today, and my course finished earlier than expected, so I zipped over there and picked it up. YeeHaw!!

And to cap it all off, they also removed the “VFR Only” and “No Aerobatics” restrictions. I had discussed my intentions to ask for those restrictions to be removed with the inspector, and had detailed the methodical approach I would take to fully evaluate the aircraft in each of these areas. He must have been quite happy with the approach I planned, as the new paperwork has removed those restrictions too.

It’s been a very protracted flight test program. First flight on 30 Aug 2008, and finally out of the flight test phase 13 months later. Four months lost after the engine/prop overspeed event, and six months lost after the car accident, but finally out of the official flight test phase. I still have lots of flight testing I plan to do over the next few months, but I’ve done everything I intended to do before I started carrying passengers.

I want to take Terry up for her first RV flight ASAP, but we are stuck in the middle of a long spell of horrible weather. Nothing but low overcast cloud and rain showers. It might break for a few hours on Friday, but I’ve got a meeting from 10 AM to 4 PM, then a flight simulator session that won’t end until around 10 PM. Drat. Hopefully the weekend will be better than the current forecast.