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Hi folks,
So what happened to my engine???
Three of the four screws & star washers holding the air box to the air intake servo were sucked into the compression chamber of the #4 cylinder. A single remaining screw and the scat tubings were all that was left holding the airbox in place. The screws and washers were happily bouncing around inside the chamber, banging around until it all either disintegrated or was spit out to the exhaust valve. Both upper and lower spark plugs were fused (no gaps) and I think this was the main reason the engine started shaking. My guess is that both spark plugs simply stopped working and the engine ran on three cylinders... The screws and washers were probably banging around inside the cylinder for a few weeks before both spark plugs finally failed.
Close inspection of the other cylinders showed nothing out of the ordinary. Oil filter was removed and closely inspected. Again, no metal shavings or anything at all was found. Compression test on the remaining cylinders were also fine. New jug/piston assembly is on order and hopefully, I should have the my plane back sometime next week.
Instead of using screws and star washers to hold the air box, I asked the mechanic to use bolts and safety wire the bolt heads together. FYI, the air box were held together this way when I got the engine and figured it was an acceptable configuration. Apparantly not.
Errors made: when Peter mentioned the engine roughness a week ago, I should have immediately pulled the cowlings off and inspected all the spark plugs. Doing so would have prevent this unplanned landing altogether. Yeah, stupid and lazy... I even remember saying to Peter that this has never happened before (i.e. plugs fouling). Lesson learned: I something happens to your engine that has never happened before, investigate immediately!
I have to say that luck was on my side yesterday: airport only five miles away with 6,000 runway, VFR conditions, under approach control, engine did not completely die (oil still moving around for the prop control & power would have been available if I needed it), only one cylinder was affected, FBO on field and the mechanics were nice. It could have been much worse...
As an aside, good friends for Princeton airport (Thanks Joe Sr & Joe Jr!) picked me up last night and took me back to 39N. Even got to fly Joe's Skylane back. Don't you just love the aviation community...I sure do!
Rick Argente
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