DA 50 update

Diamond air recently posted more information about the DA50 SuperStar on their website, it is even possible to reserve one ! I won't recopy all of the information here, but I just want to highlight some points.

Unlike the DA40 and DA42, the DA50 will have a dual G1000, with two PFDs and one central MFD. This is possible because Diamond moved the circuits breakers on the ceiling.

The engine will be a 350 HP turbo continental, controlled by a FADEC. The prop is not yet defined, and could be 3 or 4 blades. It won't be pressurized, but offers built-in oxygen, and TKS de-icing as well as a parachute are optional.

They announce a speed of 200+ kts in the low flight levels, which seems credible, depending the definition of "low", but the PA46 familly has the same performance, with pressurization.

DA50 is a five seater, but Diamond call it 4+1, as the 5th seat is between the two normal back-seats, which is the way the automtive industry is doing for years, so one more time Diamond re-use automotive ideas.

Begin a modern aircraft, the DA50 will include some goodies, like an MP3 player, and other gadgets.

Trust the FADEC... but monitor it

Sorry Thielert boys, but as any system, your contains some flaws. I will not put apart my "Plastic Evangelist" cap, or deny all what I wrote before, but will just report here a problem I had.

This happend after taking of from a 3500ft AMSL mountain airport. During climb, we (I say we because I was on the right seat, a friend of mine in the left seat, so I had a perfect observer position) reduced power to 95%, because the day was quite hot.

Passing 5'000ft AMSL climbing, we got a "low volt" warning, that went off immediately. Probably one of these problems that would not have been noticed on a classical not FADEC monitored engine.

Approximately 30 seconds later, the FADEC decided that 95% power was not a good setting, and it reduced to 65%. My fellow pilot did lower the nose to maintain speed, and we started troubleshooting the problem. However after 15 seconds, not even the time to switch to FADEC B to see if its perception was better, the engine was again running under 95%. To say everything, I must add that the air was quite turbulent, so the hypothesis of an unwanted throttle movement was not irrealistic.

We reported that to the maintenance, so the data has been inspected by a Thielert approved mechanic. This is where the FADEC played its black -box role perfectly. The mechanic could confirm:

1) the low volt transient alarm
2) the power loss
3) the fact that the throttle was not moved !

The problem had been reported to Thielert, and it was unknown at this time. I will report on this if I get an update.

This event was of no consequence as it did not happend in a critical phase of flight. However, should it happend immediately after take-off on a short runway, with 4 on board, this could be more critical.

To be a bit more analytical, this kind of problem can happen on any plane, with any type of engine. What makes it feel slightly different with a FADEC engine is that it alerts you about all trouble, but you're left with so few things to do (switch to FADEC B), that you can feel power-less.

Something more about switching to FADEC B. If the FADEC A fails, it will switch automatically to FADEC B. This is the only case when it will happen. If this automatic switch does not take place, a switch allow to force FADEC B.

Most of the alerts however do come from sensor problems, and if FADECs are doubled, most of the sensors are unique, feeding both FADECs.

If you think now that these bloddy plastic engines are risky and full of single points of failure, please re-open the AFM of your airplane / engine. You could be surprised by the number of single points of failure...

Follow me to next: G1000 transition tips

Plastic engine performance

I must say something here before starting discussing plastic performance. I did not had the opportunity to fly the same aircraft with classical and plastic engine, so I can not compare pure engine performance. It is obvious that performance does not depend of engine only, but I will give here some engine performance figures.

As mentionned earlier, the FADEC gives some engine indications that are quite unusual compared to classical engine.

The classical injected engine with variable pitch prop is managed unsing Manifold Pressure (MP), Prop RPM, and Fuel Flow (FF). A diesel engine is managed using Load (in %). The instruments also indicate RPM and FF, but the pilot has no direct impact on those parameters. RMP and FF are indicative only to help monitoring.

RPM is clearly not a performance indicator, but FF is interesting. The example I will base my comment on is using a DA40D (classical instruments), with three mid-weight persons on board, on a quite normal summer day. Departure from Sion (LSGS), 1500ft AMSL, 20 °C.

Until 7000ft AMSL, flying at about 85 kts, VSI remains above 700fpm. Regarding engine parameters, the power is maintained to 100%, and remains so until 7000ft AMSL, then it slowly decreases. FF is slightly above 6 USG / H until to about 5.8 when reaching 13'000ft.

The climb stopped there to circle the local mountain peak. En route we set power to 70-75%, and FF remains arround 5 to 5.5 USG/H.

This is not a performance issue, but remind that during the whole climb, the power lever was left untouched. No RPM to set, no MP to re-increase in climb, and no mixture to set.

In terms of flight planning, the value of 6 USG/H is a safe standard. Anyway, most of plastic engine planes have huge tanks.

To close this pose, here is a picture of the standard AED / CED displays coming with Thielert engines.


More on these displays in a next post