October 2005 Flight Log

Flt Hr 82.5 Oct 29 2005

After work yesterday I flew with the new O2 sensor installed and got the first real data since the Southwest Oil Cooler and ducting has been installed. Since the previous fligths I also installed a new "Igniter" . That's really just a group of high current transitor switches  that perform like a distributor in an old car. Changing the igniter appears to be the thing that cleared up the #5 cylinder intermittent misfiring. The O2 sensor seems to have corrected the false limit to EGT on the #6 cylinder. The engine ran perfectly both last night and today on a trip to Big Bear and back to meet Marc Zeitlin and a bunch of others. If you notice I speak in rather tentative terms because this really doesn't make a lot of sense to me. I question the igniter fix because I would expect a transitor to fail or work not be intermittent. I question the O2 sensor because A) I have been told that the engine runs open loop above 3600 to 3800 RPM and B) in the past with av gas I saw no difference from before the sensor failed to after and saw no difference with the engine computer showing an O2 error or not. Now I'm using 93 octane Mogas and there seems to be an effect. Well I'm not going to question sucess. I'm just happy it is doing well.

Now on the cooling. That is not crystal clear either. I took a bunch of data and placed in in the Performance Data Sheet. Look at the charts at line 315 and 348. The one at 315 is the oil temp out of the oil cooler or in to the engine extrapolated to a hot day (110 deg at sea level). The data from last evenings flight is right in the middle of the pack. It appears that I will still exceed  my limit of 230 deg at 140 Kts on a hot day. However the coolant data on the chart at line 348. Shows the most reccent data at the bottom of the scatter band. This indicates lower coolent temps and a lower slope to the data. This seems to not hit the limit of 230 deg until 200 KTAS which I can not reach on level flight and is beyond redline. This stumps me. I kind of expected the oil temp to be fixed but thought I might need more work on the coolent. I thought this besause A) the coolent air exits to the prop disk which I found was not a very low pressure area and 2) because the exhaust support I installed blocks part of that exit area. So much for my engineering jusdgement. So, I guess I have more work to do before the next 110 deg day, however since it's October that will probably not be until at least next Spring.

I made a flight to Big Bear to meet with 6 other Cozy builders. The temps all the way round trip were excellent. The oil inlet temp never got above 180 deg. I flew loose formation with Don Herzstein. What a fun day!

November Flight Log Flight Hr. 84.5

Most of November I was down for my first real Annual Condition Inspection. I did one before first flight and another after the repairs before second flight and this is the first one since then. So it's been 84 hours. The inspection went very well with only a few squawks. That is to be expected since I have been doing frequent work and inspection especially in the engine compartment. There were two squawks that could have developed into  problems. The inpection of the PSRU indicated that the large trust bearing I added on the forward side of the sun gear had galling on both thrust washers. I think this is from 2 sources. First one thrust washer was bevelled by hand to allow for the fillet at the sun gear. This was sloppy and allowed the washer to move off center and may have resulted in a scrubbing action from the bearing. The other cause is that there had been 0.003" free play in the sun gear shaft. This results in the shaft oscillating forward and aft at idle RPM where the torque is very low. It makes a rattle sound that can be heard in the cockpit. This was particularly noticable on the last flight. That action may have been hammering the bearing agaist the wahers.I installed a new bearing and new washers. The washer next to the sun gear was replaced with a 0.080" thick washer instead of 0.030" and the bevel was done at the machine shop. I machined off some material from the aluminum retaining block to account for the increased thickness and to reduce the free play to create a .003" preload instead. I also replaced the oil seal with a viton seal since the rubber seal was brittle from the heat and had a slight leak. This also took a little machining of that block since this seal is 5/16" thick. The other item found was that the manual crank for emergency nose gear extension broke while testing a seal I placed to block air from the wheel well. I found that the guide on the electric lift was rubbing on the shaft during electric actuation and had machined a groove in the shaft. I relaced the shaft and moved the guide away. Now the new seal supports the shaft. I switched to 15w-40 Mobil One pure synthectic oil. This should eleminate the low oil pressure when hot at idle. I sealed all holes where air could come in the forward cockpit. I found that the brakes were about 40% worn. It looks like they will go to about 200 hrs on a set of pads.

I did a check flight just before sunset yesterday. All was very good. The rattle at idle was gone and the cockpit was warmer. It was 68 deg OAT and with the heater on full it was warm but not too warm. On colder days it will need more heat. The new nose wheel cover may have increased the ROD on final a little but not dramatic.

December Flight Log - Flight Hour Ending 92.0
Eversince I switched to Mogas at about hour 60 I've been getting some power surge. Mostly it has been only on the first takeoff. The RPM smoothly drops from 4500 to about 4300 for about 10 sec then goes back to full power. Sometime it does this surge 2 or 3 times. At pattern altitude I reduce power and it stops and does not come back after that even at the same conditions. There have been a couple of occaisions where there has been a very short missing period during cruise flight but this is different in character. The latter is rough running while the former is smooth only with an RPM loss. I think the latter may have been the left O2 sensor going bad since at one point the computer indicated both a bad #1 injector and the Lt O2. I checked the injector and it tesed good. The O2 read different than the right so I changed it. So far that symptom has not returned. Study of the surge problem indicates that it is usually accompanied by an indication of knocking. The Select Monitor shows a RTD condition of 10-32 degs during this incident. Sometimes is does not but I think that is when the duration is too short for the computer to latch. I bought a new ECU modual that has a modified high power timing curve and an "87 octane" curve. I have tired both of thosenow but the problem persists. Earlier I checked the knock sensors and they appear normal. I'm speculating now that there is truely a vibration in the engine that the sensors are picking up. Perhaps it is a problem developing or it could be a vibration from the prop, PSRU, or Prop/exhaust that is not normally present in the car. I will attempt to isolate the knock sensors to see if the problem goes away.

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