Plastic engine - Operational aspects

Let' s have now a closer look to plastic engine operations. The first change compared to classical engine appears during pre-flight check. The good old oil level check is still present, but an additional check is needed: the level of coolant. This is because these engines are water cooled, so a visual check of the coolant level pops-up on the pre-flight checklist.

Engine startup is slightly different as well. The classical sequence looks like:

1) Electrical power on

2) Engine master on

3) Glow - No Glow

4) Startup

5) Check oil pressure within 3 seconds (yes, three, not thirty)

6) Warm-up

The engine master is the switch / key that turns the FADECs on. The point 3 is probably the most unusual for classical engine pilots. To burn correctly, the JetA1 fuel must be warm enough. For startup, there are "glow plugs", that bring cylinders and fuel to a good temperature.

The glow plugs activity is indicated by a particular light on the panel. After turning the FADECs on, the glow plug is activated, and then pilot must wait until the glow plugs are off before starting.

Starter can then be activated, either via a key or a push button, and normally, the engine fires-up quickly and easily. Here comes a BIG difference compared to AVGAS engines: the oil pressure must be in green range within 3 seconds !! If not, the engine must be stopped by switching the FADECs off. This very short time for oil pressure comes form the very high injection pressure.

Once started, engine can not be taken to more than 1400 RPMs before all temperatures (oil, cooling, gear-box) are in the green. This normally takes less than 2 minutes.

After taxi, comes the time of engine check. This is where FADECs help you, pilot, to save time. Just press and hold the ECU test button. Then FADEC "B" will be activated, and change prop pitch, after what FADEC "A" is re-activated, and also changes prop pitch. If all alert lights are off, the engine check is finished. The whole sequence lasts for about 10 seconds.

An additional check on the Diamond aircrafts, is to force activation of FADEC B (more on that in a later post), to ensure that both work fine.

Not more to say. For take-off, just push the power lever forward, check that more than 95% power is available, and fly. Full power can be maintained, as long as the temperatures remain in the green. In summer, it is better to reduce to 90-95% for the climb.

Most manufacturers recommend to fly in cruise with power setting arround 70-75%, but as I mentionned before, there is no restriction, and it would be perfectly legal to fly 100% all time.

One more advantage of water cooling is that power can be reduced to 0% at any time without any thermal shock risk. Quite helpful for high approaches. One must just note that most diesel engines are producing thrust even on IDLE power.

After landing, a cooling time is mandatory on Diamond aircrafts, but strangely not on Cessnas. The engine is stopped by simply switching the engine master (FADEC) to off. Be warned, these engine do stop quite abruptly.

More on engine parameters error reporting in the next post.