and just because it seems relevant to the what do you do with no instrumentation theme:
A while back I ferried an agcat to an operator. At 1800rpm and 28" (R985, 55% power) the CHT (single probe) was showing in the redline, from memory it started at something like 210°C up to 280°C (absolute redline for this engine is an astonishing 550°F!) This is a low power setting, and I was getting around 220°C. I think it is because of the complete lack of baffling to direct the airflow to the rear of the cylinders, that's my guess.
Before I did the APS course I would have just sat it there for the next few hours because frankly there isn't much you could do about it. But being a hubristic know it all I thought hang on.. and pulled the mixture back until the seat-o-meter felt that deceleration just so, and added a sprinkle of "MP and voila! CHTs dropped to around 200°C, airspeed much the same. With absolutely nil engine monitoring save the CHT I knew this was a happy, smooth running LOP round engine, just by what the CHT did. Just gotta look at what's printed on the APS T shirts.
Ok to spruik the T-shirts?
(The ag boys didn't like the look of the exhaust pipe at all when I landed, I'm sure they sooted it up soon enough though. Buggered if I know how these engines survive in actual ag operations - slow, no baffling, max continuous power... now there is a good argument for the superior reliability of turbines, compared to what I'm guessing happens to these motors)
Last edited by Lumps; 31st Jan 2016 at 10:35.
Reason: more anecdotes