An Overhaul Experience

N60146 was purchased in 1993 knowing an overhaul was due. The TTSN (Total Time Since New) was 2045 hours, more than 200 beyond TBO (Time Before Overhaul) 1800 hours. The rational behind my purchase was, I would hopefully get to know the plane before overhaul, and I would know exactly what I wanted overhauled . That is exactly the way it turned out.  It seems that overhauls are not created equal.  

Well, I got to fly 146 for about 4 1/2 years before having to overhaul the engine. For everyone there is a time that you just can't go any longer. For me, max was 2400 hrs. If I didn't have that many hours on it by the summer of '98, I was going to overhaul it anyway. My mechanic kept a close eye on the O-200's health and always said I'd know when it was time. I thought "Yeah, when I'm in the trees somewhere!". But alas, he was right, the May '97 annual indicated the #2 cylinder was about 20/80 where all cylinders had been the 77/80 range previously. Just a couple of months before I had to have an oil leak from cylinder #4 fixed so I felt that this was the time. No use fixing one cylinder to just turn around and have the whole thing overhauled the following summer. Funny thing, the plane seemed to fly fine with that one really low cylinder pressure.

Because this was a first time overhaul, the case was OK, as were the crank and the cam so there was no rework there. I think that means there were no cracks in the case and the crank and cam were not worn too much. I put on a new magneto a couple of years previously so I opted for another new one. The starter always was a marginal as it would occasionally not spin the prop when the key was twisted to the start position the first time so I had a new starter installed. I heard great things about millennium cylinders so I had them installed to round out the overhaul. The overhauler also overhauled the alternator and the carb. I don't know if they were rebuilt. Oh, I had a new spinner and backplate put on as the old backplate was repaired after a crack somewhere along the line and the tip of the spinner wasn't quite centered causing it to look as it was wobbling. The spinner is really quite long so it only has to be off a little to really look bad. I didn't have the new spinner painted as I want to polish it. It looks like it sure is going to be a lot of trouble getting those little swirls to polish out. Lastly I had an oil adapter installed.

Baffle webbing and some muffler repair finalized getting everything together. After filling the engine with mineral oil my mechanic stood by as I turned over the engine for a long minute and thirty seconds with the plug wires off until the oil pressure indicated about 50 lbs. Wow! That new starter really cranks. Start-up was rather anti-climatic as it started right up. I was a little surprised there were no final adjustments. It seemed eager to get flying. An hour flight with the overhauler was nice and smooth with the oil temp up higher than I'd seen it before. A small oil leak developed above the vacuum pump has been taken care of.

The first 10 hours were uneventful with the oil temp a little high but not as high as the first flight after the overhaul. I kept the rpm between 2500 and 2650 as instructions were to "not baby it, but don't go over red line (2750). My tach reads about 50 rpm low as checked with a handy handheld rpm checker.

I put regular straight weight oil in after 20 hours and have had only one other small oil leak the overhauler fixed without charge. The oil temp really didn't go above normal after about 10 hours so I think it was probably broken in then.

So, I guess that's it. A friend with a 150J like 146 said recently that planes like this aren't for sale for less than $20,000 back in '97. Well, maybe so, but there is so much more I want to do to make it nicer.  The cost of the overhaul including the millennium cylinders was $8500 (summer of 1997).  The oil filter adapter, baffling, starter, and spinner were purchased separately.  After over four hundred hours (almost12years) the plane flies great.  

For comments, suggestions, or questions please e-mail me at ken@cessna150.net.