Columbia- Mechanics Course day 2
posted in Columbia |Tuesday started with some interesting discussions about some future developments at TCM. Don spoke about the newer FADEC engines. They feature 6 computers, one on each cylinder and he claimed that their ability to adjust the spark timing and other factors results in an 18% increase in fuel economy over existing engines. If true thats a pretty big deal- an extra 200NM range would be an incredible boost. They also will take off somewhat leaned and will automatically go rich if a cylinder is over-temp.
My problem with the FADEC system is that they define over-temp as 420C, while I would never want to run my engine over 400C for an extra margin of safety. If this were adjustable, that would be great. Its also not clear that failure modes like an induction leak or unbalanced cylinders would be as visible- with adjusting each cylinder it could just keep the airplane flying without any indication. On the plus side, he said their goal would be with the extra
safety and automatic adjustments in the engine to get FAA approval for no fixed TBO- you just overhaul when the engine monitoring says its time. It should also be able to run on unleaded gas. While it could run on auto-gas, you wouldn’t want to do that because of the additives. Still, it would enable the introduction of avgas that is 92 octane, unleaded, and not dependent on the current expensive additives.
At an extra cost of only $4000, this seems like it could be a winner, but I don’t see it taking over very quickly.
For the Reno air-races they did a special version of the TSIO-550 that could go to 3300rpm and 60″ MP for 600hp. Of course this engine needs to be overhauled every 10 or so hours, but it does show some of the power capabilities of the basic platform that we use. The TSIO-550C used in the Columbia 400 is identical to the TSIO-550E which gives 350hp, but is just de-rated to 310hp which buys you a TBO of 2000 hours instead of 1600 hours. Since those extra 40hp aren’t
really needed to take-off or climb in our aircraft, this is a pretty big win.
He also mentioned that TCM has built a 4-cylinder diesel as part of a collaborative project with NASA. They don’t plan to bring it to market since they don’t feel there is much of a market for the lower power engine, but they are working on a 6-cylinder version that shouldn’t weigh more than an existing 6-cylinder avgas engine and will produce 320-340hp.
A lot of the rest of the discussion today was an interesting demonstration of just how far TCM has come around and been influenced by the GAMI guys. They don’t see eye to eye on everything, but unlike Lycoming they don’t have their heads in the ground. Back in the 60s, the engine manufactures ignored LOP operation since gas was so cheap. GAMI revived the practice and in doing so also helped shine a light on the details of how these engines work and issues like balancing the fuel and air flow into the cylinders of the engine. It seems to me like TCM has responded pretty well, switching to the top-induction design, working on airflow, providing tuned injectors and approving LOP operation of their engines. Since Lycoming hasn’t followed it seems like they are at a big disadvantage of the high-power
side of the engine market.
A fuel-system setup is a required part of your annual inspection. Some people apparently have been tempted to skip this in the past but it doesn’t seem like a good idea given how much we rely on getting the top performance out of our airplanes. Another tidbit was that the fuel transducers we see in the cockpit are probably only calibrated to within about 2 gph of the real values. I’ve done some test flying with some other Columbia pilots and we saw some interesting disparity in fuel-flows at identical power settings, but this variation in the transducer could explain a lot. I’m hoping to see if I can get my shop to compare my gauges to their more sensitive instruments at my next annual.