Page 22 - Volume 14 Number 1

So why did I write that you should be doing ECTM? I did so because ECTM has another, and perhaps more widely held, meaning: The recording of engine cruise parameters even though there is no intent to plot them on a graph nor use them for an HSI extension. In my opinion, the regular recording of engine parameters in cruise is quite important. Let me explain.
Memory can be a fickle thing and the older we are, the more fickle it becomes! For most of us, the ability to view, record, and store all of the engine parameters that ECTM tracks is an impossible task. “Let’s see ... what was the RH Fuel Flow the last time I flew at FL250? How did it compare with the LH side? More? Less? By how much?”
On the other hand, if we have a written record of all engine parameters taken at least once per day while steady in cruise, memory is no longer required. We can merely look up the answers. Here’s an example of why that is useful.
A few years ago, the C90A that I manage for its owner developed a larger split in the ITT readings than I was used to seeing. The change was not large, a little less than 10° C if I recall correctly. Yet over a period of three or four flights the change never went away. It was definitely something different from what I had observed previously. I did a Flow Pack check – thinking that perhaps one
side had become very weak, leaving more P3 air in the engine and hence making it run a bit cooler – but the packs seemed normal in all respects. By looking at the ECTM raw data records that I had been keeping, it became instantly obvious that the shift in ITT readings showed up on the first flight in which ECTM readings were recorded after our previous maintenance event in which Phase 3 and 4 inspections were done together. Back to the shop we went and in short order a relatively minor change in the ITT wiring harness was found and corrected.
Had we not had past readings to analyze, it would not have been obvious that this change came on suddenly following work at the last shop visit. In fact, the ITT change was so minor and all engine parameters were still well within limits that it would have been very easy to shrug our shoulders and merely accept the readings as normal.
Recently a King Air owner/pilot friend of mine had a shock when a badly deteriorated Hot Section was discovered during a routine Phase inspection. The maintenance personnel believed that the ITT was reading much lower than the correct value and hence the pilot had been running the engine much too hard and too hot ... leading to the need for all new CT (Compressor Turbine) blades. There are 58 of those beauties and they aren’t cheap!
20 • KING AIR MAGAZINE
JANUARY 2020