Twin-Engine Trainer Comparison

[CFIDave]

The March 2015 issue of Aviation Consumer magazine published an article with tips for selecting the right twin for multi-engine training. While I can't legally reproduce the article here, some of the points made in the article were interesting:

"Diamond's diesel-powered Twin Star elicited sharply divergent opinions from flight instructors. Most said it was a lousy multi-engine trainer because it was too easy to operate."

- The DA42 is a poor trainer for anyone forced to later fly other piston twins, since additional training will be required for avgas engine shutdown/feathering. With its % power (load) indication the DA42 is really appropriate only for students moving on to jets.

- With a stick and responsiveness of the T-tail, performing steep turns within tolerances of the PTS was difficult. So difficult, in fact, that local DPEs (examiners) were made aware of this and presumably cut students some slack during checkrides. (I have to agree that steep turns are challenging in the DA42, unless you "cheat" by using synthetic vision to hold the Flight Path Marker on the Horizon Line. :-D )

- "Rudder forces at Vmc were the highest of the light twins we flew." (I find this to be believable, given how much pressure is required to hold course flying OEI without using rudder trim.)

- Because the Thielert-operated DA42 prohibits engine shutdowns above 8500 feet, the flight school operating out of Denver was forced to fly 80 miles east to find lower ground elevation. The local Denver-area FSDO has dropped the requirement to demonstrate engine shutdowns and restarts in the DA42. (FYI, Austro-powered DA42s have a higher 10,000-foot limit for engine shutdown/restart.)

- The single-engine rate of climb of 150 fpm at sea level is "atrocious," and the single-engine service ceiling is only 4000 feet. (I found this Thielert-powered DA42 characteristic surprising, given that our Austro "dash six" offers 280 fpm at sea level and can climb all the way to 18,000 feet on one engine.)

- The average annual inspection before any squawks were addressed was a high $12,000. (In contrast, our DA42 annual inspection was only $3400 last year.)

As you can tell from these points, the magazine didn't like the DA42 very much, and preferred the tried-and-true Piper Seminole as their number one choice, with the Technam P2006T worth considering as operators gain more experience with it.

[rwtucker]

"Diamond's diesel-powered Twin Star elicited sharply divergent opinions from flight instructors. Most said it was a lousy multi-engine trainer because it was too easy to operate." . . . The DA42 is a poor trainer for anyone forced to later fly other piston twins, since additional training will be required for avgas engine shutdown/feathering. With its % power (load) indication the DA42 is really appropriate only for students moving on to jets.

These are interesting points Dave. I have been saying the same thing about the DA40 in the single engine training space. If I had been trained in a DA40 I would have a very different impression of the size of the "forgiveness" envelope in slow flight, impossible turns, and more. I read recently that Cirrus aircraft are becoming more common in training (a result of the manufacturer's initiatives such as underwriting insurance). Maybe this is a good thing or maybe it means that we will kill student pilots.

Do you agree with the concern about single engine flight in the 42? The first time I flew a 42, I found it difficult to believe how well it flew once I trimmed the rudder and went to 100%. I kept waiting for the drop that never came.

[CFIDave]

Do you agree with the concern about single engine flight in the 42? The first time I flew a 42, I found it difficult to believe how well it flew once I trimmed the rudder and went to 100%. I kept waiting for the drop that never came.

With all light twins you have to work hard at configuring the aircraft exactly right to eke out a climb (e.g., "raise the dead" engine w/2.5 degrees roll, 1/2 ball out with the rudder, pitch exactly to blue line), and the DA42 is no exception. When training with just instructor and student, typically empty aux fuel tanks, and no baggage, in my experience it's not unusual to obtain 300+ fpm climb rate in a Thielert-powered DA42. (I've seen 600 fpm one engine inoperative (OEI) in our DA42-VI). Engine out practice is why recurrent training is so important in a twin.

In some ways the DA42 is easier to train in because of the precision of the load (% power) indication. For example, simulation of the drag of a feathered prop in a DA42-VI can be obtained by setting exactly 11% power on the "failed" engine. For single-engine descent in the pattern or on an approach you set 70% power on one engine -- exactly twice the 35% power setting normally used for 2 engines. (These percentages are slightly different for Thielert or NG DA42s.)

There also don't seem to be Vmc rollover accidents in DA42s compared to Piper Seminoles (during OEI training or otherwise) -- the Aviation Consumer article neglected to discuss the safety record of light twins used for training.

[ememic99]

... in my experience it's not unusual to obtain 300+ fpm climb rate in a Thielert-powered DA42.

Last year during my IR/ME exam I got 300 fpm with 3 adults on board and more than half fuel on board, OEI, on the blue line with fethered prop, 3 deg roll and 1/2 ball.