LETTER TO THE EDITOR:
Re: Paul McBride’s column, “TBO: 2,000 hour or 12 years,” in the June 23 issue: This is absolutely the best article I have ever seen on the subject.
I started oil analysis every 25 hours the day I bought my used C-180. The original engine (which had a “log cabin overhaul” by a very reputable mechanic) went to TBO with no problems.
My “factory reman” replacement from Continental was making a bit more metal from day one, but the reports were quite stable. My mechanic son insisted on cutting each filter open and examining it with a magnifying glass and magnet, in addition to the oil analysis. I always kept the last five used filters for comparison.
At 500 hours, with the plane fueled and loaded for a flight in the morning, I got a call from my analytical service stating the Nitraloy had spiked and to do a compression check. The engine had been running fine with absolutely no indication of a problem. Mag checks were perfect. It was smooth and the power was normal.
We found one drastically low cylinder and pulled it. The exhaust valve stem was found to be shaved down to one half normal diameter by the Nitraloy guide, obviously primed for a catastrophic failure. Oil analysis saved the day, in my opinion.
Now the good part: There was no accident and Continental only charged me for the time flown, although the engine was out of “calendar” time, so I got another “reman” for $10,000 rather than the going $15,000.
DOUG MILLARD, Wasilla, Alaska