C172 TDI cockpit retrofit

During a recent flight with a C172 retrofited with a Thielert 135 TDI engine, my passenger was kind enough to make some inflight photos of the cockpit, so you can show how it looks after the diesel adaptation.

My apologies to the photo gods, this is not exactly a great luminosity balance, contrast, and whatsoever, but it shows what it has to.

The first big change is obviously the AED / CED displays, positionned each side of the control column. The one to the left is partial on this plane, as there are no fuel quantity gauges, this plane still uses the original ones.

You can see on the left indicator that the engine is burning 7.3 USG / H of Jet A1, and the right side one indicates that the prop is turning at 2280 RPM, and that the engine is developping 96 percent of its power.

All parameters are in the green, but if it was not so, some LEDs would be orange or red. As you can see, even in this visibility, the LEDs are easy to read, which is true under any light conditions, as far as I can say after more than 50 hours of flight using such indicators.

Other changes to this vintage Cessna cockpit can be noticed on the left side, below the fuel gauges. Here is a new panel with some lights, for low fuel, glow, AED and CED alerts. On the top row are also two buttons: the left one is for the FADEC test, and the rightmost one is to acknowledge any caution / warning.

In posts about FADEC operation I mentionned an "Engine Master" switch. On this plane, it is the big gray switch just below the electrical master, in the bottom left corner of the picture. To avoid any misuse, it is the kind of switch that must be pulled to operate.

The final change to the cockpit (except for the single lever, not shown here, but hey, it's only a lever), is the switch to force FADEC B to be active. It is under the red cap, just left of the hand microphone.

DA42 double and simultaneous engine failure after take-off

Here is a quoted text following the belly landing of a DA42 after a double and simultaneous engine failure.

"Twinstar take-off crash divides Diamond and ThielertDiamond Aircraft Industries and Thielert Aircraft Engines are at loggerheads over the cause of a double engine failure involving a DA42 Twinstar during take-off in Germany last month. The incident, in Speyer, south-west Germany, is being probed by the Germany air accident investigation bureau, but the cause of the engine failure is known to be the effect of a transient drop in the electrical voltage to the two engine control units, Diamond confirms. The European Aviation Safety Agency has ordered the companies to find a swift solution, and Diamond's chief executive Christian Dries says his company is seeking EASA certification to install a small back-up battery for each engine's control unit. When the crew of the accident DA42 arrived at the aircraft (D-GOAL) they found it had a flat battery and started up the engines using an external power unit. This deviated from the published operating procedure, which only allows one engine to be started with an external power unit - the second has to be started using aircraft-generated power. Just after rotation, as the landing gear was retracted, the aircraft experienced simultaneous engine failures on both TAE Centurion 1.7 diesel engines, forcing the crew to make a belly landing in a field adjacent to the runway. Diamond says that retracting the gear placed a load on the electrical supply from the engine-driven alternators that caused a temporary voltage drop that could not be covered by the flat battery, and the accident has shown the engine control unit to be intolerant of transient electrical fluctuations. TAE says the problem is an airframe issue, adding that being forced to issue an airworthiness directive for the 1.7, which is set to power other aircraft types, would have a huge impact on its business. Diamond dismisses these claims and argues the control unit supplied by TAE should have been able to accept a 50 millisecond transient, but it started to reset after 1.7 milliseconds, and during the engine control unit reset the propeller system sensed the power loss and auto-feathered. Meanwhile, Diamond has issued a service information bulletin that clarifies standard operating procedures. Dries says the question remains: who is to pay for the fix?"


I don't want to blame or finger-point anyone. The german investigation bureau will establish the facts. My only personnal feeling (and it is not more than that) is that taking-of in a plastic engine plane immediately after a known battery problem is arguable.

Any update will be published here.

UPDATE: new information and a service buletin are discussed on http://www.plasticpilot.net/blog/2007/09/03/da42-double-engine-failure-service-bulletin-published/

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.

Few words about planes and plastic revolution

A plane is made of three major components: the airframe, or fuselage, the engine (sometimes in packs of two...) and the instruments, normally located in the cockpit for pilot's use.

Some would argue that the pilot itself is part of the plane. This theory will be particularly "en vogue" by certain pilots who live true relationships with their planes, but no, the pilot is not part of the plane. MM Cessna and Piper never delivered any pilot, as far as I know.

Airframes have been made of a wide variety of substances, wood, fabric, paper, aluminium, and occasionally with addition of insects or birds.

Recently however, the plastic revolution took place. Ok, some like to call it "carbon fiber", or with even more complex names, including chemical formulae. Nevertheless, when you touch such a plane, or gently hit the wing (yes, gently only), it sounds just like plastic... because it is.

Let me be very clear. Wordings like "plastic plane" or "plastic flying" may sound cheap / unsafe / risky. This is not my point at all, and this blog is precisely about my own experience of flying plastic planes.

I just call them this way because it's fun, and fun is all what flying is about.

Back now on the three components of a plane. Airframe is easy, and know you can share my concept of "plastic airframe".

Engines are more a metallic thing. But just like plastic changes the airframes, a recent change happened in light aviation engine technology: turbo-diesel and FADEC. With that kind of engine, the pilot gets rid of many possible mistakes, a.k.a. prop and mixture lever, pumps, carburator heat, and so on. So to distinguish these new engines from the classical one pilots were used to, I call them "plastic" engines.

And what about instruments ? A bit before the plastic engine revolution, instruments moved from electro-mechanical individual dials, to integrated "tv-like" panels, that manufacturers names "glass cockpits". As they are LCD panels now, the term "plastic" cockpit would be better, would'nt it ?

Any plane can then be classified depending the ammount of plastic in it, from nothing to all plastic (airframe, engine, instruments), with all possible variations.

As mentionned above, this whole blog is about flying planes with plastic components, and I wish you plastic fun while reading it.