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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.

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Monday 12 Oct 2009
0.5 air time
0.6 flt time

Inter-flight activities:

  1. Extended under-cylinder head wrap around baffle on bottom of #1 cylinder, in an attempt to raise the CHT.
  2. Tightened inverted oil lines to hopefully resolve two oil leaks.
  3. Removed one link in tailwheel chain
  4. Connected wing leveler pushrod to flight controls.
  5. Conducted wing leveler ground test procedure and adjustments.

Purpose:

  1. Navaid Devices wing leveler flight test

Events:

  1. Checked wing leveler performance at low and cruise speed in wing leveler mode.
  2. Checked wing leveler performance at cruise speed in GPS track mode, with GPS in enroute sensitivity.
  3. Checked wing leveler performance at cruise speed in VOR track mode.
  4. Checked wing leveler performance at cruise speed in GPS track mode, with GPS in terminal sensitivity.
  5. Checked wing leveler performance at intermediate and final approach speed in GPS track mode, with GPS in LPV angular sensitivity.

Results:

  1. Wing leveler works well in both wing leveler and track modes. Turns in wing leveler mode are smooth. GPS and VOR tracks are followed within about 1/10 deflection of the CDI needle, without control stick oscillations. No adjustments needed. Need to test in turbulence.
  2. The use of the wing leveler promises to greatly reduce the workload during cross country flights. The wing leveler appears to do a better job than a pilot of tracking the lateral navigation signal. The aircraft is quite stable in pitch once it is trimmed, so the workload to hold the desired altitude is quite low in smooth air. Testing will be conducted in turbulent air.
  3. #1 CHT is still significantly lower than the others. The reduction of the under-cylinder baffle gap caused a very small increase in the difference between the hottest and coldest CHTs.

New Snags:

  1. None.

Existing Snags:

  1. Max rpm still decreases late in the flight.
  2. SD-8 Alternator - must run power wire to regulator.
  3. Pitch trim speed of movement is slow during a touch and go. Need to try it with the pitch trim speed governor removed.
  4. #1 CHT is about 50 deg F lower than the others. Probably should recheck the CHT probe calibration in boiling water as the next step.

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Thursday 08 Oct 2009
0.7 air time
0.8 flt time

Inter-flight activities:

  1. Semi-permanently installed rudder trim tab using 3M double-sided tape.

Purpose:

  1. Cruise performance testing at 8000 ft

Events:

  1. Cruise performance test at 2400 rpm, wide open throttle (WOT), 50 deg F lean of peak EGT (LOP).
  2. Cruise performance test at 2600 rpm, WOT, 100 deg F rich of peak EGT (ROP).
  3. Cruise performance test at 2150 rpm, WOT, 50 deg F LOP.

Results:

  1. Pending data analysis

New Snags:

  1. The ball is now very, very slightly to the left at the typical cruise condition. While it was perfect when the trim tab was taped in place with the wedge flush against the rudder skin, the double-sided tape that now holds it in place is about 0.06" thick. This puts the tab out slightly more into the airflow, and apparently increases its effectiveness. The tab must be trimmed slightly.

Existing Snags:

  1. Max rpm still decreases late in the flight.
  2. SD-8 Alternator - must run power wire to regulator.
  3. Pitch trim speed of movement is slow during a touch and go. Need to try it with the pitch trim speed governor removed.

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Thursday 08 Oct 2009
0.4 air time
0.4 flt time

Inter-flight activities:

#. Temporarily installed rudder trim wedge using metal tape.

Purpose:

  1. Rudder trim check

Events:

  1. Checked rudder trim at the expected typical cruise condition of 2400 rpm, wide open throttle, 50 deg F lean of peak EGT.

Results:

  1. All three balls (EFIS, turn and bank, and wing leveler) were centred.

New Snags:

  1. None.

Existing Snags:

  1. Max rpm still decreases late in the flight.
  2. SD-8 Alternator - must run power wire to regulator.
  3. Pitch trim speed of movement is slow during a touch and go. Need to try it with the pitch trim speed governor removed.

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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.

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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.