Transition to Diamond DA-40

After training almost exclusively with a Cessna 172 Model N, I am now transitioning to a model Diamond DA-40. I have had the opportunity to fly 172 SPs. The 172 SP has basically the same engine as a DA-40 (Fuel Injected Lycoming 180 HP). So, there is some overlap on the procedures. However, the SP, M and N models have every similar flight characteristics. The Diamond is a bit different. This blog entry describes those differences that stood out for me.

As one would expect with a low wing, the landing roll is longer, as the plane enters and stays in ground effect longer. The wing span of the Diamond is greater than the Cessna 172. With lower wing loading, the take-off, climb an turning performance of the DA-40 is superior to the 172 SP. On the flip side, the 172 SP feels more stable in wind gusts. In the DA-40, I did feel more like a feather than within the 172.

The DA-40 has T tail. Flying with a T tail had only on significance to me in standard flying conditions. In a 172, the air movement from the prop wraps around the plan and interacts directly with the horizontal stabilizer. A drop in power results in a fairly pronounced drop in the nose. In the DA-40, I found this effect less pronounced. Please note that T tails have a disadvantage in slow turns, as disruptions from a stalled wind reduce the flow over the tail, deepening the stall.

I have heard that cross wind landings are more difficult in the DA-40, in part due to the low wing, reducing the amount of aileron that can be used in the flare and, more importantly, a small rudder. I am not convinced on the last part. For a test pilot, this may be true. For myself, I did not notice any less effectiveness in cross wind landings than the 172. Those wind conditions that test the plane's performance (about 15 its cross wind component) are outside the conditions I willing to try in either machine.

To get a sense of the transition to a DA-40, I am going to start at the ramp and walk through key parts of the check-list that are different and significant. I am picking only parts of the check-list thats meet this criteria.

On the ramp during the pre-walk around, I switched on the battery. I noticed that, given a few seconds, the engine instruments give me a more accurate reading from the digital display. I can get oil temperature and CHT. This is great in the winter to get an idea if preheating is necessary. The fuel indicators seem fairly accurate. It is a bit harder to judge the fuel visually since the tank filling ports are higher on the wing. After flying for over an hour, the gas will not be visible on a flat ramp. When lowering the flaps, I noticed they are tiny. There only two notches of flaps. I could not tell what the degrees are from the panel. My guess would be something like 10% and 30%. On inspection of the flaps, I though that the effect of the flaps on a T tail may be a different, with less disruption of air flow over the horizontal stabilizer. The battery is on, I noticed may of the instruments were working such as the attitude indicator. Why? Because the attitude and compass (HSI) are electrically powered. The 172 uses a vacuum pump powered from the engine.


The start up procedures are similar to the SP. The ammeter is not turned on until after engine start and engine instruments are in the green. It is best to pull the mixture a bit after start to prevent fowling of the plugs during taxi.

Taxiing the DA-40 is a more of a challenge than a 172 due to the free-castering nose wheel. Gentle tapping of breaks to handle direction changes is necessary for control in many situations.

At run up, the prop needs to checked. Pull the prop gently all the way back and then push it forward quickly. You do not need to wait for an oil pressure change. The change will show during the push forward to 2700 RPM. If it does't, try it a couple of more times to get the oil moving through the prop governor.

Before take-off, the fuel pump is turned on, on notch flap is added. Mixture and prop are full forward (low altitude). Take-off is easy and quick. If there is a bit of shake during the latter stages of the take-off roll, the nose wheel is has gaining too pressure so pull back (slightly). The Da-40 accelerates quickly. Watch the airspeed and hold the plan in a climb at around 80 kts. The DA-40 climbs very quickly. Once in a positive climb, bring up flaps, then adjusts prop to 2400 and, once safely above the 'deadly turn; height, shut off the fuel pump.

Watch the Engine temperate. At low altitudes, the DA-40 moves. I am always in the yellow arc when leveling off at low altitudes. So, it makes sense, at low altitudes, to adjust the manifold pressure to 24 inches.

Once in level flight, adjust the mixture. Switch the to EGT and pull back the mixture slowing until one of the CHTs flashes. Then notch forward on the mixture until the hottest cylinder is about 1400. I noticed in level flight, trimmed for cruise, the DA-40 has a nose-down attitude in comparison to the 172. I loved the visibility. Speaking of nose down attitude. Check out the two passenger weight balance for a DA-40 with full fuel. This places the plane near the forward CG line. This means there is less 'room' to pitch up before approaching the 16 degree angle of attack.

I practiced stalls in the DA-40. It feels just as stable as a 172 to me. Recovery is quick and easy. The DA-40 throttle and controls are extremely sensitive. I need a light touch to make adjustments. Trimming is a piece of cache with the trim control on the stick. I still like the trim wheel!

In descents, a little more planning is required. Slowing down the DA-40 for the pattern takes a little more time. I keep the prop at 2400 RPM and ease back the manifold pressure to 18 inches. When in the pattern, I hold the plane at 100 kts until abeam of the numbers, then I apply one notch of flaps. Then, I pull back to about 15 inches and start my turning descent. On final, fuel pump is turned on, mixture full rich, prop full forward, and the landing light on. I adjust the manifold pressure to about 11 inches. Once landing is assured, I lower the flaps (second notch) and begin brining the power back. It is critical to keep the speed above 70 kts. The stall speed of the DA-40 is not as advertised. Once level with the runway in the flare, just pull back really slowly to slow down the plane. It settles nicely. Do NOT let the nose drop, as the nose wheel is not as forgiving as a 172. Aggressive pulling on the stick is not necessary. A slow steady pull keeping the nose slightly high is sufficient. Too much pull causes tail strike or, even worse, a premature stall above the runway, causing a bounce. If this happens, apply power, holding the stick steady. The plane will begin settle again.

Through out the process, I realized that the work load of the DA-40 is a bit more than the 172 models. That's fine by me. It moves me closer to the load of an RG and proficiency requirements for a commercial rating. In the end, the most important element is the ability to fly the plane. Of this, I have no doubts that I can handle the DA-40. Out of 5 landings so far, two were smooth and gentle. The other three were a little rough.