Flight #17                                       

Conducted 12/21/2012 -

When we had done the first stall/stability test with a weight of ~1900lbs, the results from the stall testing left us confused, as the speeds seemed to be much higher than we were expecting. The only other oddity John noticed that could have been a factor was that the ASI seemed to be reading a bit ‘sluggish’, that is to say it was responding slowly. It was indeed very cold out that morning, but we wouldn’t have thought it should effect the mechanics of the gauge.

We’ve been secretly hoping that we’d be able to break the 20hour mark by the end of the year, and we only had a couple hours to go, so a couple weeks ago, on our first day of holiday break, we decided to retest at the same weight and CG point. Although it was still cold, the ASI didn’t appear to be sluggish as John barreled down the runway. In flight, the needle movement was much more responsive to pitch changes than the previous flight, and the indications at stall were much more in line with our expectations (63-64Kts straight ahead). The only thing we could theorize is that it had gotten a bit of ice in the pitot tube, though where from we couldn’t guess.

After the flight we started pulling the cowls and covers for our routine post flight test inspection, and noticed a film of oil all over the aft engine baffle and the cowls. We pulled the dipstick and found it had lost about 1/4-1/2 quart on the 1.7 hour flight (placing me it 19.5hrs). Not alarming, but it sure made a mess. Searching for the leak, it appeared that one of the pushrod tube seals was leaking a bit, but it didn’t seem like it was enough to create the mess were seeing.  We had gotten a SAIB from the FAA about the spring clips on those tubes becoming weak and that new clips had been manufactured of a better material.  Being we had all the parts already, we elected to replace all the tube seals and springs before the next flight.  We didn’t want our silly end of the year quest for the half way point to cloud our judgment. Besides if the work went smoothly (which it did), it wouldn’t take that long.

After buttoning everything back up, we did a ground run of the engine for about 45 minutes to get everything warmed up and check for leaks. Sadly, there was an oily film on the aft baffle again, but everything forward of that was dry. It seemed that it had to be coming from somewhere aft of the baffle. The only sources for potential leakage we could think of back there were 1) the prop governor oil line 2) the prop flange to prop extension o-ring 3) the prop extension to prop hub o-ring 4) the main crankshaft oil seal, or 5) the prop hub itself.

It was dry at the prop governor oil line, so that was easy to eliminate, but the next three would require pulling the prop.  We could find no indication that either of the o-rings were leaking as we pulled the prop and the prop extension, but upon removing the flywheel we could see that the oil seal at the crank snout was our culprit. Unfortunately we wouldn’t be able to obtain a new seal until after Christmas, as none of the local suppliers were open until the 26th, so no flying for our next 4 days of vacation.