"yr right" wrote:
Anyone that thinks it safe to fly with a leaking exhaust valve with a comp 5/80 has a serious problem. Maybe you should go read the lyc and tcm sb. Also tcm allow low leak rate. You have to use a a special metered orifice that when set correctly allows you to measure the lowest leak rate you at have pAst the rings. Tcm and lyc do NOT allow any leakage past the valves. Walter has misleading made a statement.
No one, including Walter, made any such statement. I don't expect you to read, understand, or acknowledge this message, and that's ok. Others may find it interesting.
He did say that he did so experimentally, AFTER determining it was safe by borescoping, and by engine monitor data, both tools that we in GA did not have a few years back. He had the "intellectual curiosity" to go beyond blindly trusting the existing lore. No animals or humans were harmed during these TESTS. CMI (nee TCM) has, more recently and to their credit, greatly modified the new documents coming out of the factory.
We all have been removing cylinders blindly and unnecessarily for slightly low compressions for decades, simply because we did not have the tools to do it any differently, NOR DID WE OR THE FACTORIES HAVE THE KNOWLEDGE.
Walter had the "good luck" to discover that his engine, in his personal airplane (TN Bonanza) had the classic symptoms of yesteryear that would require cylinder rework. Using the new tools (borescope and EMS), he kept on going, while keeping a very wary eye on it. As we suspected, it ran fine for a long time.
It might be interesting to know HOW he ran it. About 20 years ago we were looking at test data, and wondering how these engine would run LOP (Lean of Peak) for the long term. We mutually agreed that we would all run them full time at max possible rated power, LOP. So George, Walter, and John did it, using our own personal airplanes, fully aware that we were taking a risk that we'd have to pay for. Others heard of the "experiment," and joined in, and we all shared data on the Internet Forums (another "tool" that we didn't have before.)
Today, hundreds, if not thousands of pilots are doing it. For the TNIO-550/520 equipped aircraft, that power setting is WOT (Wide Open Throttle, about 30.0"), 2500 RPM, and mixture up to 17 GPH (64 lph), which is roughly 90℉ (50℃) LOP, and 85% to 90% HP. We all ran OUR OWN engines that way (ALL THE TIME) to TBO and well beyond. None of us had a single cylinder removal, and to my knowledge, no one beyond the three of us have either, at least caused by this.
That's DATA, not opinion.