Pietenpol-List: A Neat Trick for Pietenpol Maintenance

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matronics
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Pietenpol-List: A Neat Trick for Pietenpol Maintenance

Post by matronics »

Original Posted By: "Greg Cardinal"
I know a lot of you are still building your Pietenpols, but we have quite afew flying now. One of the great advantages of building your own airplaneis the ability to do your own inspections, but we don=92t ever seem to discussmuch how to go about inspecting one. Here=92s a neat trick that I came upwith today.One of the tasks that should be done each year at the annual ConditionInspection is to check and reset the magneto timing on the engine. Themethod I=92m going to describe will work on any engine, as long as you knowwhere the ignition should be set. On a Continental A65, both magnetosshould be set to 30=B0 BTDC. Continental puts a mark on the propeller flange(for some strange reason, they put it on the bottom of the flange, where itis nearly impossible to see) that you are supposed to line up with the splitbetween the crankcase halves. If you can get it within a couple of degrees,you=92re doing pretty well.Aircraft Spruce sells a nice digital instrument that straps onto thepropeller hub and can be set to zero when the # 1 piston is at top deadcenter, and then the prop can be moved to the angle desired before top deadcenter for setting the mag. The digital device is accurate to +/- 0.1degrees. It also costs $109.85.Today I was doing an =93Owner Assisted Condition Inspection=94 on my RV-4, anddecided to see if I could do better than just using the timing marks on theback of the starter ring gear against the crankcase split (Aircraft Sprucealso sells a nice little spring clip pointer that fits Lycoming startergears to enable a bit more precision in aligning the timing marks. It sellsfor $41.75). I went to Home Depot and bought a digital level for $39.95.It is accurate to +/- 0.1 degrees and has a nice feature in that you can putit at any angle, push the =93reset=94 button, and then it will read any changein angle from that set position.Back in the hangar, I pulled the top plugs from each of the cylinders of theO-320 in my RV-4. I moved the prop around until the timing marks indicatedI was close to TDC on the # 1 cylinder. I looked in the spark plug holewith a flashlight and could easily see the top of the piston. I moved theprop back and forth a bit until I was able to determine exactly where TopDead Center was. Then I taped the digital level onto the prop, checked thepiston again to make sure it had not moved, and reset the level to read =930.0=B0 =94. Now I moved the prop backwards until the level read =9325.0=94, whichis where the magnetos should fire on an O-320. Once there, it was easy toset both magnetos to fire exactly at 25=B0 BTDC. I checked to see where theyhad been set at last year=92s condition inspection (which was done by an IA atan FBO) and found that they were both firing at 23.6=B0 BTDC, or nearly adegree and a half late.Here is a picture of the setup:The setup is very easy and should work for any engine on any airplane.Total cost - $39.95 plus about 2 cents worth of blue painter=92s tape.Jack PhillipsNX899JPSmith Mountain Lake, Virginia________________________________________________________________________________
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