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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.


  1. Navaid Devices wing leveler flight test


  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.


  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.

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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People in this conversation

  • Hi Kevin.

    Enjoying the reports.

    I've been impressed on my airplane the degree to which CHT is sensitive to
    mixture variations between cylinders. IMHO baffle modifications should be
    deferred until the injectors are carefully balanced so that each EGT peaks at
    about the same fuel flow.

    I of course always like to recalibrate sensors--I've been accused more than
    once of being anal.

    James Freeman

  • James,

    Thanks for your thoughts.

    The four EGTs hit peak over a fairly narrow range of fuel flows, and this
    cylinder is quite a bit cooler at all fuel flows. I don't think the issue is caused
    by low fuel flow to that cylinder, but I'll study the data a bit more closely
    before I completely throw that cause out.

    I did check the CHTs in boiling water about two years ago, and they all were
    within 2 deg F of the expected value, and the variation between highest and
    lowest CHT indication was only 2 deg F at that temperature. They also
    indicate very close to the expected ambient temperature when the engine is
    cold, so I don't think there is a major indication error. But, I will recheck
    them in boiling water, just to be sure.

    Kevin Horton

  • Is your harness flexible enough to swap probes between cylinders 1 and 3? Seems that might be quicker and easier than the boiling water, plus would identify any potential issues at a higher temp range.

    Your probably right about the bafffles though, ultimately.