When most people think of Mooney, they think of speed, lots of speed. It was this premise that in 1989 brought the aviation world the Mooney M20M -- TLS. Introduced during the French ownership era, the M20M was 1 of the "one new model each year for 5 yrs" program initiated by Alexandre Couvelaire during the mid-eighties. The M20J -- 205, the M20J -- Lean Machine, The M20L -- PFM and the Advanced Trainer System (ATS) were the 1st 4 aircraft with the M20M completing the package at the end of the eighties.The TLS was a big departure for Mooney Aircraft engineers who were known for their "performance through efficiency" approach to aircraft design. Not since the M22 Mustang, had such a combination of airframe and big engine been considered in Kerrville .Using an airframe based on the one-foot longer M20L fuselage stuffed with a turbocharged and intercooled 270-horspower Textron Lycoming TIO-540-AF1A engine, the M-model was to be the most powerful Mooney produced since the 1967 -- 1970 pressuri ze d Mustang. The original goal was for 214 KTAS at 25,000ft -- the designed max operating altitude. However, the airplane would actually do closer to 220 KTAS! Some people, myself included, think this longer body airplane was the best-looking Mooney ever built. With it's stretched nose, long sleek fuselage and the longer side windows, the TLS looks fast sitting still.And fast it is. The engine is a version of Lycoming's parallel-valve; 540-cubic-inch opposed 6 with a single AiResearch Turbocharger and carries a max power rating of 38 ins manifold pressure and 2575 RPM. Two controllers operate the single wastegate to regulate pressuri ze d air to the induction system. With this system, the engine is capable of maintaining its full 270 horsepower up to FL210 under standard conditions. With this high 21,000-foot critical altitude, the TLS is able to achieve very high cruise airspeeds. At FL250, as high as you can legally fly in the M20M, it's still possible to utili ze max continuous power -- 34" and 2400 RPM, which is about 240 horsepower or 89%!Of course all this speed comes at a cost - about eighteen gallons of Avgas per hour of cost to be specific. And that is if you lean aggressively to the 1750-degrees-Fahrenheit turbine-inlet temperature (TIT) max, 1 of the highest certified TIT's in piston aircraft. We will discuss leaning in detail again later in this report.One thing did become evident during the 1st few years of production. With the airplane delivering such high cruise airspeeds, at high altitude with high power settings, many TLS owners discovered that their airplanes needed engine work at 400 to 500 hours.In retrospect, this could be a predictable situation. Here we have a large-bore engine producing 270-horsepower and in the hanger next door may be another variation of the TIO-540 in, say a Navajo Chieftain, producing 350-horsepower. It would be easy for the average TLS operator to think his engine was a de-rated version of the 350-horsepower monster. At 270 horsepower it's not working as hard as the engine in the Piper, and using nearly 90% of that number for cruise should pose no major problems. Unfortunately, this premise is incorrect. The two engines have little in common. The engine pre-owned in the TLS is rated at 260 horsepower without the turbocharger -- at a higher compression ratio and RPM -- and is really a lightweight version of the Navajo's 540. As a result, exhaust valve guides bore the brunt of the wear from these operations.There was a predictable rise in oil consumption and dropping compression readings during as little as 300 hours of operation. Fortunately, these excessive wear indicators did not lead to any catastrophic failures. But many owners discovered that a quarter of the way to overhaul, top-end engine work was necessary. 1 of the factors in this increased need for unexpected maintenance could have been the high TIT red line. Most turbocharged Lycoming engines of that day had a more conservative limit of 1650 degrees F, and they had a better maintenance picture than the early TLS's.Mooney and Lycoming came up with a solution for the TLS top-end wear problems. A process that Lycoming pre-owned successfully to cure similar problems on the TIO-541 Beech Duke engines -- oil cooled exhaust valve guides -- was accomplished on the TLS. The illustrative name "wet head" was given to the conversion that was accomplished on all production engines that resulted in a designation change to TIO-540-AF1B. The change from the AF1A to the AF1B brought about the nickname for the engine, the "Bravo mod", and in fact the TLS became the TLSBravo and has since been shortened to just the Mooney Bravo.In this conversion (and on subsequent production engines) oil is fed under pressure to a carousel in each cylinder head adjacent to the exhaust-valve guide. The guide it self has a small groove cut into the outer diameter allowing oil flow to surround the guide and draw away heat. From the valve guide, this additional oil flow is routed through the rocker boxes where it helps to draw away additional heat and then through the normal drains back to the sump. The modification is easily seen as a bunch of snaking external oil lines leading to each cylinder head. Our info is that all US airplanes have been modified (Mooney paid a substantial part of the Service Bulletin), however some foreign TLS's may have been missed.To date, 314 M20M TLS and TLSBravos have been manufactured with the last 1 (27-0316) rolling off the Kerrville production line in 2001 just prior to the factory shutdown. By the way, the TLS designation came from the engineering department who referred to the airplane during testing as the Turbo-Lycoming-Saber. Marketing had at 1 time thought of naming the new model the Mooney "Saber" as they were trying to get away from using the max airspeed for the model name as on previous Mooneys.Let's take a look at some statistics on the M20M