december 2011 volume 11 • number 12 - American Bonanza Society

www.bonanza.orgIhave learned over the past two yearsthat the color of green warns ofimminent failure.Exhaust valve with green crescent showing.“Steve, I have learned over the past two years that thecolor of green warns of imminent failure. I want you tofly straight home, put your plane in your mechanic’s hangarfor your annual and tell him to pull this cylinder.”Adrian had been able to clearly see the pattern describedin the Continental Service Bulletin.My engine had not been looked at for the past year.My 12-point engine monitor had not warned me of anyproblems, including on the flight home (and you canbe sure that I was watching it!). The previous year’s oilanalysis, compression test, and oil filter inspection hadnot raised any flags. Engine starts were fine, as was theoil consumption.The next morning I taxied my warmed up Bonanza tothe maintenance hangar, where my mechanic, LarryDonaldson, and I first tested the five good cylinders, whichagain tested fine. When testing the suspect cylinder, wecould hear air coming out the exhaust pipe immediatelyand the cylinder tested poorly. This cylinder had to comeoff. Once off, it was evident that the exhaust valve andvalve guide needed to be replaced. We shipped thecylinder off to Skyline Cylinders in State Line, Pennsylvania,where Tim Barnes had previously rebuilt my othercylinder. He rebuilt this cylinder in short order, and afterinstallation it is now doing well. The rest of the annualwent as expected.Volume 11 • Number 12 AMERICAN BONANZA SOCIETY 15