lml@lancaironline.net Mailing List Archive

My noise didn't sound like it was coming from the engine. more like something banging on the fuselage. Just happened 2 or 3 times and then stopped. I had done some carbon work since the last flight so possibly it was some bubbles popping but it seemed loud for that.

My engine is set up for 45 gph in the climb.

On May 4, 2010, at 4:23 PM, Robert Pastusek wrote:

Colyn,

On the loud banging/popping, could the engine be pre-igniting? This will definitely cause what you describe, and is definitely not good on it. Do you climb at full rich mixture? If so, pre-ignition is not likely…but possible. If you are leaning in the climb, try pushing in the mixture the next time it happens to see if that corrects it. Also, you can get a pop/bang from “after-fire” in descent with the mixture rich. This is caused by unburned fuel being dumped into the exhaust during descent when the engine is essentially windmilling…not producing much power… The fuel mixture will occasionally ignite in the exhaust stack causing a definite pop/bang.

You’ve got the old window for asking. I don’t have it out yet…probably be June as my “real work” is significantly interfering with my fun these days, but I intend to try to get it out in one piece so I can try to see where the break started, and why.

According to Ed, the crankshaft failed between the bearing journal and the prop flange…right in the radius. Ed says you can see a crack through at least half the material, then the rest “tore off”, bending/distorting the metal in the process. Don’t know if this was one of the “bad” Continental cranks that got through the check of a few years ago or not. The NTSB has the engine and is analyzing now. Expect to hear more about this when available.

Bob

From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Colyn Case
Sent: Monday, May 03, 2010 6:40 PM
To: lml@lancaironline.net
Subject: [LML] Re: Cabin Door Window-IV-P