Tuesday, May 15, 2007

Plastic projects

I stopped posting last days, mostly because I think I went quite arround the topic, given my present experience.

My plastic projects for the time being include the plastic challenge, which is to fly plastic engines only for 2007. Obviously any new plastic opportunity would be good, like flying an avidyne cockpit, or a Cirrus or Columbia aircraft. I don't mention the DJet, but who knows...

This blog is still open for comments, and any news about topics left open (as the gelcoat issue, or the DA42 incident) will lead to new postings.

Saturday, May 12, 2007

Plastic Evangelism Hard Time

Some friends / fellow pilots / readers call me "Plastic Evangelist" or "Diesel Evangelist", because of my well known enthusiasm for plastic flying. I fully agree with them and I assume this nickname.

However the downside of it is that each time a plastic plane has a problem, some come back to me, with a big smile, pointing out that these plastic technologies are dangerous, can not be used in aviation, etc...

Anyway, as a good "evangelist", I never change my mind nor to change their, but I always repeat the same info, re-state the same arguments, endlessly.

The strange point is that most of time, the people criticizing plastic planes are the same that years ago criticized GPS. I think of a particular friend of mine that flies IFR, and learned it before GPS. He is really good and safe at it, no point here. When GNS430 came in the game, he just used it as a NAV/COM. He was not really against it, but he just did not wanted to make the effort of the change.

However as more and more RNAV only waypoints pop arround, he started to reluctantly use the GPS part, and slowly converted to full GPS use.

My point here is that plastic technologies are still considered as "new", and each incident will be pinpointed... and if you're a plastic fan as I am, you should always keep in mind that the change going on is coming from true technological, operational and economical trends, and the safety aspects are also important, so this change will continue, it's only a question of time.

Who reminds the time where IFR was without RNAV ? Amongst those of you who drive manual shifting cars, who reminds the time of "double clutch" ? I'm sure where cars were introduced, many people objected that they had sooooo inconvenient compared to horses...

Only time will tell... don't be tough to non-convinced people.

Plastic Evangelist

Friday, May 11, 2007

Plastic Engine Cessna 172

You're getting bored of DA40 planes ? Lucky you, I will now post about a C172 in which a plastic engine has been retrofied. Unfortunately for my own experience, it has classical instruments, and is VFR only. I think you need to know that I converted to C172 by the very end of last year, and I never flown a classical engine C172 before (except as PAX...).
Nothing special in engine handling compared to the DA40, as it's the same powerplant, same FADECs, and nearly same AED / CED. On this particular Cessna, the fuel quantity indicators are still the old gages, they are not integrated in the new indicators. One noticeable difference in engine management compared to DA40 is the cool down time. After landing, you have to run on IDLE power for two minutes with a DA40, whereas you can stop the C172 immediately. This is probably due to the much larger air intakes in the C172.
For C172 classical engine pilots, a new issue will raise: fuel management. I'm sure you all manage fuel properly in terms of quantity, but with the diesel you have to care about balance as well, because the new fuel system does not have a "both" position for its fuel selector, so you'll have to switch tanks periodically. If you fail doing so, you riks a fuel imbalance, but also temperature problems.
The particular C172 I fly now had the long range tanks options, but the tanks have been reduced with the plastic engine retrofit. They have now a capacity of 20 USG each, so an autonomy of about 6h40... Should be enough for most operations.
When comparing the performance graph, it seems that the diesel version is slightly less performant below 5000ft, but then the turbo advantage makes the difference. On a normal day, I could once climb from 1'5'00 ft to 13'000 ft in less than 25 nautical miles.
One important restriction concerns the TDI engine bad reaction to fuel starvation. The high pressure pump can be damaged it if runs witouht fuel for more than 15 seconds. As a consequence of that, long out of balance situation could lead to severe engine damage. I know at least one case of pilot who loss engine power during a long side-slip. The club management answered to this issue by prohibiting side slips...

Wednesday, May 9, 2007

DA40 differences training (JAR)

This post presents what you can expect from a DA40 (plastic engine) differences training under JAA rules. I talk here of a DA40, with classical instruments, not G1000.

The theory part will focus on diesel operations, but that's easy, and on electrical system, which is of paramount importance when a plastic engine is part of the game (see my post about the DA42 double engine failure...).

Then comes the practical flight. As I already told, the DA40 is really a forgiving plane, thanks to its good wing desing. You will go through various but all uneventful stalls, and manoeuvers like steep turns.

As always, you will have the landings practice then. Normal, engine off, and so on. Some changes here about the fuel and FADEC system. The typical drill for engine failure is:

1) Maintain speed (as always)
2) Try force FADEC B
3) Activate fuel transfer in case you pumped all of the main tank

If you've enough altitude, you can try an engine restart, but before doing so you have to switch engine master to OFF and back to ON, to activate the glow plug for pre-heating.

Depending on the lift / drag ratio of the plane you flew before, your first landings can be really floooooooooaaaaaaaaty. Remind to come with the correct speed, corresponding to your weight, and you'll land ok.

The final stage of your differences training should include flapless landings. This is because the flaps are electrically driven, so JAR make that mandatory (quite smart on this topic...). As you can imagine, flapless landing in a floaty plane is not exactly the easiest part of the training.

In my very particular case, the differences trainig took 4h03 of block time, including a solo nav of 30 minutes, and dual flight to another airport than base which were needed because I was checked-out by the new club at the same time. The exercices part took something like 2h45.

Tuesday, May 8, 2007

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/

Monday, May 7, 2007

DA40 - Cabin interior and wings plus pictures

One other thing in DA40 that makes it match my criterions for a modern aircraft is the ease of access, and cabin layout. All of those who flew a PA28 with passengers on the backseat know what it is about... DA40 access for front seats an back seats is easy, specially because a rear side-door is available.

One noticeable thing is that the front seats can not be adjusted, as they are integral part of the fuselage. The stick is part of the seat, and the rudder pedals can be adjusted. There's not too much space in the cabin compared with a PA32 or Bonanza. Diamond did however put a lot of effort on designing the back seats. As already mentionned, they are easy to access, and there is enough space for two adults (w&b permitting), but the most enjoyable thing is that the back seats are sligthly higher tha the front row seats, so the passengers can have a decent forward view. To convince yourself, sit down in a PA28 / 32, and then in a DA40. You will have no doubts which is better as a PAX.

Now, regarding the wings. As I said in previous post, the wingspan is ENORMOUS, for a total of 12 meters (close to 36 feet), leading to a high glide ratio, and low wing loading. An other interesting thing is that flaps are very wide, but not so deep, as ailerons. You can see that on the next picture.

You can also constat the the wingtip has a mini winglet. On DA42, the winglet is huge, close to 50cm high. The new version (DA40 XL) also has a larger winglet.

As I'm in my photo library, I can not resist to the pleasure of giving you a photo of one of the famous local mountain, known as Cervin or Matterhorn. Picture from FL130.

Sunday, May 6, 2007

Comment and answer

I had this interesting comment as an answer to the "Trust the FADEC... but monitor it"

"Hi, yesterday a plane crashed into a bay in Flensburg - north Germany, and 4 people died. If the press ist right it was the DA40 with the Thielert-Diesel from a sports clup in Flensburg. So I googled the word "blackbox" because the press said "the blackbox was found" and i hadn't heard of blackboxes in single piston planes before. It is disturbing to hear from you, that the powersetting of the FEDEC seems to have a mind on it's own. Just speculating: What if you do sightseeing - slightly slow and low and heavy - and the powersetting changes just a bit - while you are talking to passengers - would you realize the loss of speed early enough?"

So my three answers to that. First all my sympathy goes to the familly and friends of all the people touched by this tragedy.

As an attentive pilot, you will notice any power change by noise change. I fly with a Bose X headset (thanks Santa...), but I still feel any power change, except may be very slight one, but such changes won't have impact. Even if you don't notice it, you will loose speed, and the stall warning will manifest itself quite early (see the previous post), and the stick will become less strong, and this should help you to notice the approach to stall.

Second part is that low and slow is never a good combination, so it depends how you define them. Anyway JAR OPS requires a minimum of 500ft AGL (more over crowded areas), and despite its nice stall characteristics, flying close to stall speed is never a good idea. This kind of problems can happen with any engine, be it FADEC equipped or not. You could have to manage a capricious mag, a fuel line problem leading to starvation, or fuel contamination on any plane. If you want time to react or more time to find a landing spot, slow and low is not a good option.

If your passengers want to see a particular spot (let me gues... their house ?) just circle it instead of flying slow.

Thanks for the comment anyway, they're always welcome.

DA40 - Aerodynamics

This post is the first of a series about the DA40, partly about the plastic technology, but more generally.

What is noticeable with the DA40, but also other plastic planes (Cirrus, Columbia, ...) is that they are a brand new generation of planes, designed from scratch, taking full advantage of plastic. This has impact on how wings are designed, but this is also a product of modern computer aided design tool.

One my preferred characteristics about the DA40 is its stall characterstics, which make a stall kind of a non-event. Let me be clear here. I don't say that you can't stall a DA40, if someone design once a non-stallable plane, I would be really interested ;-)

What makes the DA40 stall good and safe is that stalling it does not induce any drop, be it wing or nose. The plane just falls (about 1300 fpm / 40 kts). Compared to nose drop common to PA28 or C172, it is even more uneventful. My basic training took place on a plane that lost at least 700ft in wing / nose drop at any stall.

A part from the pelasant way of stalling, feeling safe and smooth to the pilot, the factor that make it s safe plane is that the risk of spin is really low, as no drop occurs. And given the ENOURMOUS wingspan of DA40, the ailerons maintain efficiency at very low speed.

On the back side, ENORMOUS wingspan leads to a very low wing loading (weight per square meter / feet of lift generating surface) makes it really reactive to turbulence. Any wind speed change, or thermal lift will have strong effect, so flying precisely requires a quick reaction time.

The second consequence of low wing loading is that it glides really well, but precise landing is not easy. Depending on weight at landing, speed can be adjusted from 58 to 70 kts on final, and beleive me, adjusting is important. Approach with 5 extra knots, and you will have a long flare, which can be critical on runways shorter than 800 meters (2400 ft).

Another strange thing is the stall warning, which from my point of view sounds too early. If the wind is slightly turbulent on take-off, it is quite common to have a "stall-warning check" immediately after take-off. I don't feel it good to have a stall warning horning arround 65 when the plane can fly at 45. May be next versions could include a flap dependent stall warning, however as the stall warning is not electrical but pneumatic, it's not so easy.

Saturday, May 5, 2007

G1000 Nav setting / beacon identification

This post addresses a topic that is more IFR oriented, but can also affect VFR pilots using radionavigation.

As all IFR navigation is based on radar vectors or radionavigation, it is of paramount importance to properly tune the nav receivers, and the corresponding indicators.

The routine I used on planes with classical intrumentation was:

Nav 1 - Frequency - Course selector - Ident - DME coupling - RMI coupling
(same for nav 2)
ADF frequency - Ident - RMI coupling

The G1000 includes two nav receivers and an optional ADF receiver. In terms of indicators, there is an HSI which also includes two RMI pointers, as seen on the picture below:

This indicator is really flexible and powerful, may be too flexible in fact.

The HSI needle can be coupled to NAV1 / NAV2 or GPS. Each pointer can also be coupled to a NAV, GPS or ADF. When you've to fly a complex procedure needing more than one or two navs, you can define a setting that matches it, but then tuning the G1000 and then interpreting it is not obvious.

The school where I trained had a standard setting which was:

Primary NAV or GPS on the HSI, NAV2 on le single line pointer, ADF on the dual line pointer. One desing remark here to M. Garmin: on classical instruments, the single line pointers are green, and the dual line pointers are yellow. On the G1000, they are both cyan.

Having a standard setting help you to easily interpret your pointers, and to resist the deadly tempation to spend too much time during an approach to build up a specific setting. It could seem restrictive, but in fact it helps remaining proficient.

Another important topic is the identification of beacons, by identification of morse code. The G1000 includes a morse decoder, so when you tune a nav frequency, it will "listen" to the code, and display it. This value is not comming from the database, so it can legally replace the identification by a human. But unfortunately, this feature is not available for ADF and DME.

More on DA40 specifics in the next post.

Thursday, May 3, 2007

G1000 transition tips

Here again, what I can tell is how I made it, which worked quite well, but there is no absolute / universal way to manage this transition, which is not obvious as it could seem.

One first advice is that if possible, you should to your G1000 transition on a plane type you already know, so you can truely focus on the G1000 only.

The first step is to do some theory training, either on your own or withing a school with an instructor. I took such a one day course, but I prepared myself by self-studying before. Material for this includes the User Manual and Cockpit Guide published by Garmin (available on www.garmin.com). Be careful when choosing your download. As the G1000 includes engine parameters display, there are variants of the documents to match each plane type.

Garmin also created a software simulator running on PC. Not on all PCs, by far not as only a few video chipsets are supported. Unfortunately, this simulator is only delivered to people actually buying a G1000, and it is not available for download. Nevertheless, as some clubs did buy such planes, they put it on the internet for their members... Using the google searchbox on top of this page, you should be able to find it easily, especially if you look for Norwegian aeroclubs...

If you can run it, this is a good tool, but as there is no throttle / AP like in the GNS430 simulator, its use is a bit more complex. The help file is definetly worth a good look.

The next step is to consult some books or CD / DVD / web training tools. I personally used the one from Max Trescott, which can be found on www.glasscockpitbooks.com. It is quite good, even if the procedure part addresses only the US way of flying (please remind I'm a Swissie...).

Once you will feel ok with the G1000 theory, you can envisage some practice. For the first few hours, an FNPT-II is really the good tool. If you fly on MEP, you will save money anyway. On SEP, you won't save money, but time, as your instructor can create any useful situation, failures, and so on. You will also be much more relaxed in an FNPT-II than in the actual aircraft. I made that part by cannes-aviation, a good FTO located in Cannes (LFMD), on the french riviera. They have several DA40 and DA42 with G1000, and a frasca FNPT-II based on DA42.

If you think that the FNPT-II will not reproduce the G1000 realistically given its complexity, you're wrong. In fact the sim does not repdoduce the G1000 at all, it INCLUDES an actual G1000 ! Garmin designed an external connection allowing to feed the unit from external signals from a simulator. This is why this time is really beneficial.

More on G1000 IFR nav settings and DA40 specifics to follow..

Wednesday, May 2, 2007

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

Tuesday, May 1, 2007

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