Diamond Flight Test

[mutt]

Have an offer to flight test a Diamond single engine aircraft next week, the goal is to assess it as a flight training aircraft.

Anyone want to pass comments on the pro's and con's of this aircraft, especially in relation to hot weather operations.

Thanks

Mutt

[BackPacker]

What engine does it come with? There's three possible choices: the Thielert 1.7 Centurion, the Thielert 2.0 Centurion and Diamonds own Austro engine. Or, of course, the 160 HP avgas one for which the aircraft was designed in the first place.

We have one DA-40 with the 1.7 Centurion (135 HP) in our fleet and I would consider it slightly underpowered for take-offs, particularly when compared to your average PA-28 or C172. However, the very sleek airframe still makes it cruise at 115 knots with 70% engine power, which is very good. And only uses about 5 USG/hr Jet-A.

Here are some major points that you need to watch out for when having trained or been trained on a PA-28 or C172.

- W&B: Ours is a rather heavy, full-IFR specimen. With full fuel and two adults on board, the CofG is too far forward. A 17 kg container of sand in the rearmost baggage area solves this and is standard equipment for us. Also, three adults, no sand and full tanks exceed the MTOW.
- Preflight: some new items to check, most notably the gearbox oil level.
- Starting and runup procedures are completely different. Not harder, just different.
- The wings are substantially longer and thus it's easier to taxi into something. A full castoring nosewheel is also something to get used to. If you set the power at something like 1200-1400 rpm during taxi and then leave the power alone, you have enough airflow over the rudder for all but the tightest turns.
- As said, take-off performance is poorer. In some cases the take-off roll may be twice that of a PA-28 or C172 in similar loads and conditions.
- The climb-out angle is shallower compared to a PA-28 or C172 and you need careful speed control to get the best Angle of Climb or Rate of Climb.
- At least in our specimen, the stall warner is very twitchy in the climbout and will tweet almost continuously. Very annoying.
- In cruise, careful trimming is required to obtain the 115 knots @ 70% power. If you trim it only ever so slightly too far aft your altitude will remain constant but speed will only be 105 or so.
- No carb heat, no leaning, no prop control. 100% power available up to FL115 or so, and the engine is rated to provide 100% power continuously. And watercooled, so no risk of thermal shock damage. Don't expect that your students learn the finer points of engine management on this one.
- The airframe suffers from a slight yaw/roll oscillation if you remove your feet from the rudder pedals. Use the rudder as footrests in the cruise and this goes away.
- Very noticeable pitch change when selecting flaps. If not countered immediately you gain 200 feet just like that.
- The airframe is very slippery and it's nearly impossible to fly a very tight circuit while slowing down and descending, even with full flaps. Descend planning and speed control on final is very important. If the speed drops below about 70 knots on final there's a huge sink rate which requires a lot of power to arrest.
- The demonstrated crosswind limits are actually higher than the PA-28 or C172.
- Need to relearn the emergency procedures for this aircraft. Engine failures and things like that are handled completely differently due to the dual FADEC.

If you're going to use it as an instruction/hiring aircraft, make sure that the switches at the upper left hand side of the panel have some sort of guard alongside them. They are very vulnerable when entering/exiting the aircraft. At one time someone had bumped into one of those switches on our bird and damaged it. This lead to the engine going into its FADEC test while in the circuit. The pilot handled it well and managed to get the aircraft down in one piece but the sequence of events and the resulting behavior of the engine was a very complex one, and is still not documented in the POH. The short version is, if you have a partial or full engine failure and you are (eventually) within gliding distance of the runway or a suitable field, switch the engine off with the engine master, to avoid nasty surprises (engine going to 100% power uncommanded) and a potential overshoot of your landing spot.

For navigation and IFR training, cockpit organization is more important in the DA-40 than the PA-28 or C172. The stick is almost in your crotch and there's a sizable center console, leaving virtually no space for a kneeboard or similar. I think Transair actually does a special DA-40/42 "lapboard" which folds out across both legs but has a cutout in the center so that the stick gets full travel. But a regular A5 kneeboard is already too wide to allow full stick travel.

If you intent to use the aircraft for touring, make a printout of the Diamond authorized dealers/maintenance outfits (can be found on the website) and put them with the aircrafts papers. Engine problems are impossible to diagnose without the proper tools (laptop with special connector and software) and training. I was stuck one weekend in Duxford with a "computer says no" problem and it took us 24 hours to locate someone with said laptop because we did not have that list.

Another tip: take an airtight box and put some plastic gloves, the fuel tester and the fuel level measuring thingy in it. Jet-A smells a lot and doesn't evaporate well, so the smell lingers a long, long time on everything that touched it.

We have a fleet of Robins, Pipers, Cessnas and one Diamond and I'm checked out on virtually all aircraft. The Diamond is my absolute favorite for touring.

[Pilot DAR]

I cannot speak to the DA40, having never flown one.

But, I have just completed extensive testing in a gasoline powered DA42L, and was extremely impressed. Much of the testing was engine operation in hot weather and adverse conditions, and it all went very well. It is a delightful aircraft with lots of oomph. The market will be well served by this version of the aircraft.

A few things were a bit unusual to an old Cessna Piper driver, but I opened my mind to a new way of doing things, and adapted well...

We were also given a diesel version to fly, which neither of us had previously flown, and I quite liked it as well. What a shame those engines have a challenged future, as they make a pleasingly simple powerplant for pilots to enjoy.

I can highly recommend the aircraft

Pilot DAR

[mutt]

Backpacker,

Thank you for taking the time to write such a comprehensive response :ok:

We are looking at training upto 100 airline cadets per year and a new school is offering the DA40 as opposed to the other candidate school with its C172 and Archers.

I would presume that due to our summer temperatures, the Thielert 2.0 is the minimum requirement.

What is your experience with the aircrafts reliability?

Mutt

[BackPacker]

Mutt, I only have experience with the 1.7.

Our specimen has had a lot of teething problems. Not just in the engine, but also in very minor things like the microswitches that drive the "door open" warning. I've heard similar stories from other operators, mostly here on PPRuNe, but I've also heard stories of operators who have had no significant problems whatsoever.

That is of course with the exception of the Centurion engine problems (no or very expensive spares) that hit everybody after the Thielert bankruptcy.

We only have one Diamond, which is being maintained by our own maintenance outfit (we're a large club with 13+ aircraft so we have our own personell). They obviously did not have much experience with the DA-40 but did go to the Diamond maintenance training class and have all the official tools and manuals.. After I got stuck with the "computer says no" problem at Duxford and had somebody from a nearby operator with 10 or so DA-40s flown in, that person gave me his contact details and I forwarded them to our maintenance personell. As far as I know, they've had a rather long telephone conversation between them, so that our personell now have a lot more (2nd hand) practical experience.

So if you do decide on the DA-40, make sure your maintenance guys go to the official Diamond course (don't know the details about that though) and then arrange a contact for them with somebody who maintains these on a daily basis. There is a lot of practical information to be had from them.

Oh, and there's a Diamond Owners and Operators forum on the internet as well. My club is (presumably) a member, but not me personally. So I have no idea on how good the information on there is.

[soay]

Oh, and there's a Diamond Owners and Operators forum on the Internet as well. My club is (presumably) a member, but not me personally. So I have no idea on how good the information on there is.
It's here (http://www.diamondaviator.org/), and the majority of its members are from North America. That means they mostly fly DA40s with Lycoming engines, so are generally not interested in anything to do with Thielert. Nonetheless, the forums contain a wealth of useful information. A free trial membership is available.