Test Flying DA 42 NG next week - any tips for a DA 40 pilot

[Robin]

From the questionnaire:

If the oil pressure to the propeller dome is lost, does the propeller go into
coarse or fine pitch? Fine pitch

Ouch, there goes our twin engine safety argument against Cirrus' chute!

My understanding is that constant-speed propellers are designed quite differently for single-engine vs. twin-engine piston aircraft applications, purposely built with different failure characteristics:

On a DA40, loss of oil would cause the prop to go into fine pitch, for safe flight at the lower speeds required for landing or a go-around climb.

On a DA42, loss of oil would cause the prop to go into coarse pitch, all the way to feather. As multi-engine pilots know, it's extremely difficult to fly a twin with the asymmetric drag of a windmilling prop.

So I'd still take a DA42 twin over a Cirrus 'chute anytime. :-D

Thanks Dave and Henrik for the correction

I have spend too much time flying singles lately....

From the DA 42 NG AFM page 7-27 Prop Control

Pitch is set by the ECU control of the governor. To change blade pitch angle gearbox oil is pumped into the propeller hub. Increasing the oil pressure leads to a decrease of pitch (fine) and a higher RPM. Decreasing the oil pressure leads to higher (Coarse) pitch and lower RPM.

Then on the next page under Feathering

To feather the propeller the engine must be shut down with the appropriate ENG MASTER switch. This will open the electric governor valve. All oil will flow back from the propeller hub, allowing blades to move into the feathered pitch position.

Thanks for the correction once again...

I shall give PIREPs during the next week.

Safe flying

Robin

[carym]

Robin,
I am not sure I agree with Dave's thoughts about range when flying OEI. While you can think of 90% power one one engine as equivalent to 45% power with both engines, even with the prop feather you still have increased drag so that you get less than 50% of "equivalent" power. Remember, when you lose one engine you lose approximately 80-90% of your "excess" horse power. I think that if you fly the plane perfectly (feathered, 3 degree bank into good engine, ball 1/2 width toward good engine) you will not get the range you expected at 45% power with both engines running.

In theory with the G1000 you could test this out at altitude. See what your TAS and fuel consumption is when flying straight and level at about 8000 feet and 45% power. Then, shut down one engine and fly at same altitude with 90% power on good engine and check out your TAS and fuel consumption. I haven't tried this, but it should be fairly easy and safe to do. Let me know what you find out!!

[Robin]

Hello

I promised to post reports, I had thought I would do this as went through the DA 42 endorsement, and the training leading to the flight test to renew my MECIR = multi-engine command instrument rating. It was such hard work I have left if until the end.

Having spent 10 hours in the DA 42 in the last week, I have to say I really like it. It is way more comfortable than my DA 40. I got use to the manual rudder positioning system. I dont like the engine oil dipstick setup, I do love the ECU, engine master, start technique.

I am giving my impressions on what I found was interesting or different...please feel free to add stuff that I may have missed out or forgotten.

Flight one.

General handling: very stable, heavier on the controls that the DA 40. I think Cary or Eric said previously that they missed the sports car like feel of the DA 40 after having a DA 42.

Stalling: very benign. Really felt comfortable that it would be very hard to get into the stall, and even then should be very easy to recover. Did the falling leaf "stall" rocking from one wing down to the other.

Emergency descents. Gear Down, nose down, going down at 3000' plus per minute. The instructor said that the aircraft looses it excess momentum very quickly, so you can land off the emergency descent easily.

One engine out handling. Maintain directional control with rudder, watch airspeed, gear up (hold if past the FAF), flap up (hold if past the FAF), dead leg = dead engine, confirm with throttle, confirm with load, feather if performance critical.

The DA 42 is heavier in the controls than my DA 40. But it is more stable, and less bouncy in the turbulence we had.

Safe flying

Robin

[Robin]

Quite happy with the DA 42 in the normal circuit.

For the Australian MECIR renewal we have to do...so plenty of practice of

After take off, > 400'AGL, > Vyse we have to do an asymmetrical climb to MSA. I was impressed with how well the DA 42 coped with this. Need plenty of rudder, half a rudder bar to the live, raise the dead engine 5 degrees, hold 85 KIAS.

Circling approach on one engine. Circling approach ie below the MDA maintaining 300' obstacle clearance. Why is it that the instructor always fails the engine on the outside of the turn?, to make it harder! At the Gold Coast airport, this means flying between the apartment towers, then along the beach.

Engine failure after the FAF and before the Missed Approach point. This was the hardest part for me. At this stage the CDI was in LNAV mode ie 0.3nm for full scale deflection on the RNAV GNSS approach. Maintain directional control with rudder, gear hold, flap hold. Feather the dead, which meant 11% thrust on the simulated failed engine.

In Australia the tolerance for the test was < half scale deflection. Need to really watch the CDI, I found adding in some rudder trim really helped. Need to really watch the airspeed, power upto 80% on the live engine. Then keep the descent going, we have to be within +100 and -0 of the altitude limits.

At 100' above the MDA, power up to 100% load, gear up, flap up, watch the sink! Cannot descend below MDA. All happening at once.

Safe flying

Robin

[Robin]

Just to give you some background information. Its winter downunder at the moment. Its very cold in Melbourne around 12-15 degrees Celsius, thats cold for us! So Jane and I decided to have a holiday in warmer Queensland, around 20 degrees C. This is a 2 hour jet flight north for us.

We are staying at the Gold Coast, and the flying school is a 5 minute drive up the road.

Flying out of the Gold Coast airport, YBCG. Busy regional airport with lots of domestic jet arrivals and several international flights a day. The controllers do a great job slotting everyone in.

We have a nice apartment, this is the view from our bedroom.

Safe flying

Robin

[Gnomad]

General handling: very stable, heavier on the controls that the DA 40. I think Cary or Eric said previously that they missed the sports car like feel of the DA 40 after having a DA 42.

Robin,

Really nice to read your write ups and daily impressions. Glad you are getting multiple days in the plane to put her through her paces.

It was definately me who mentioned the sports car feeling of the DA40 'after' flying the 42 for awhile. After a week in the 42 during my ME training, my first flight in my 40 once I got home, was a shock! So very nimble compared to the 42.

I have over 100hrs in my 42 now and love everything about it, but I do miss the DA40s roll rate and light stick! As you've noticed however, the 42 is much more stable in turbulence, something my wife noticed right away and much prefers. Happy wife happy life!

[carym]

As you've noticed however, the 42 is much more stable in turbulence, something my wife noticed right away and much prefers. Happy wife happy life!

Even tho the DA42 is quite stable, my wife claims that when I hand fly she gets sick and so she insists that I fly with autopilot (KAP140) on. I swear, however, that almost every time I turn it off without her knowing and she still manages to claim that I must be hand flying again because it just got rough. I know that I am a better pilot than that

Overall, I still say that the DA42 is the most comfortable plane (of the 15 different types listed in my log book) I have flown.

Robin, I bet you will be trading your DA40 for a DA42 soon!

[Robin]

Hi Cary & Eric

Thanks for your input. I did go flying on Saturday when a front came through. We did get strikes on the stormscope as did our last approach. At one stage we flew through a heavy rain downpour and I could not hear the engines at all. It was quite gusty but the DA 42 was stable, the GFC-700 autopilot did not miss a beat. Even when I had to hand fly the approach the DA 42 was stable.

We are flying VH-NGI, a DA 42 NG, see the attached photo.

We flew the RNAV - Z GNSS approach usually Runway 14, and the Runway 14 VOR approach. Gold Coast YBCG does not have an ILS. Because I already have an instrument rating, I could renew the ILS in the simulator. Here in Australia we had to do a sector entry and a hold as part of the renewal test.
See the attached approach plates.

Safe flying

Robin

[Robin]

Hello

Approach plates for the Runway 14 VOR and RNAV -GNSS are attached.

These are available on the Airservices Website http://www.airservices.gov.au

Safe flying

Robin

[Robin]

I did my initial MECIR = multi-engine command instrument rating 5 years ago, and each subsequent renewal was in the DA 40 ie single engine. So I felt quite comfortable with the approaches VOR and the RNAV GNSS. My main challenge was the asymmetrics.

Some things that I learned or had forgotten since my getting my IFR rating...

5 NM from the fix and you are going to have to do a sector entry or go into the hold. In GPS mode, press OBS to suspend the approach. Using the course knob dial up the inbound course. Power in the DA 42 NG to 50%. With the VOR approach spin the VOR course bar to the inbound track. If on autopilot use heading mode. Either handflying or on AP track into the fix using the BRG indicator. Double check that you have the right fix, have the flight plan up on the MFD, highlight your fix, in GPS mode DCT to, enter, enter.

Company policy to announce the mode you are flying on.

In Australia most approaches are 3 degrees, so to fly a CDA constant descent approach you need to descend 320 per NM.

One thing that really made sense. Most of the time with I fly RNAV approaches in the DA 40 I would be too high. I learnt in the DA 42 to GEAR DOWN TO GO DOWN, select gear and approach flap 0.3-0.5NM before the descent point. They also select VS, so as the approach point arrives you just press the DN softkey.

When flying the RNAV GNSS approach, if you are high eg 50' too high, double the error in your descent rate, ie with this error increase your rate of descent by 100 FPM.

Things that I knew

In IMC never fly with full flap.
Only activate the approach once cleared to fly the approach.
Past the FAF = final approach fix, check you are in LNAV mode, and reset the Altitude to the missed approach altitude
With gear going down, your hand stays on the handle until you have 3 greens.
With reducing power your hand stays on the throttle.
PITCH Controls ROD= rate of descent
POWER controls AIRSPEED

Cheers
Robin