2007 XL Annual - Amsafe and Guardian CO costs

[rwtucker]

. . . I read once that a DA40 in a near full "controlled" stall, slowly mushing to the ground, has a descent rate lower than a Cirrus under the parachute. May have been in Philip Greenspun's excellent blog. Granted, you are still moving forward, and part of the parachute safety is in the beefy Cirrus landing gear built to absorb the impact.
Thoughts about this?

We have talked about this in DAN and I can verify the results and the ease of the procedure as I practice the maneuver at least once a year. When I practice, I'm usually about 50-70% loaded and I get a 400-500 FPM descent rate, less than one-half of the Cirrus BLS descent rate plus you can fly again if you are breaking out of clouds after getting disoriented, icing up, finally restarting, etc. Even if you drop to the ground, the impact will be somewhat controlled and hopefully not into a tree or a lake. There is some forward motion but it is difficult to gauge because of the stalled wings. I'll look at the GPS next time.

[BlueYonder]

Airlines have to put the airbags in now, because the seat pitches are too close now for people to bend over and brace properly. There is literally no room left to do it. If you've got an airbag, you're probably in a too-small seat, too. I share Colin's wonderment at the amount of explosives that means they're carrying, and also the potential for mischief on the part of someone who might want to deploy that resource for their own purposes.

N172MZ, I'm 838. Savvy Maintenance supervised my annual, which helped keep Clay Lacy under close rein. There was a fair amount that needed doing (first year of ownership, so I encountered some deferred maintenance like the Amsafes), but I'm fairly well-assured at least none of it was spurious. As a first-time owner, hiring a maintenance manager has already paid for itself several times over.

[ultraturtle]

I read once that a DA40 in a near full "controlled" stall, slowly mushing to the ground, has a descent rate lower than a Cirrus under the parachute. ... Granted, you are still moving forward, and part of the parachute safety is in the beefy Cirrus landing gear built to absorb the impact.
Thoughts about this?

The article was posted on AvWeb: https://www.avweb.com/blogs/insider/AVw ... 652-1.html

Basically, in a full stall, the DA40 descends at an average of 900 fpm (varying 600-1,200 fpm) at 48 kt IAS with full directional control, i.e. the capability to steer to an impact point. The Cirrus under parachute descends at an average of 1,290 fpm (900-1,680 fpm) with no directional control whatsoever. At first glance one might consider it a simple tradeoff between 48 knots of airspeed vs 390 fpm of vertical speed, but this would disregard the two very important factors of wind and directional control.

Directional control is all important if the pilot has the information available to guide the aircraft to a survivable impact point, whether that information comes from the Mark I eyeball in day VMC, or his SVT display at night or IMC. The Diamond, even in a full stall, has directional control, the Cirrus under parachute does not.

Wind is nearly always a factor. Considering the case of a 24 kt surface wind, the Cirrus would impact wherever the wind sends it at 24 kt ground speed at an average descent rate 43% greater than the Diamond pointed into the wind toward a spot of the pilot's choosing at the same speed.

Add 26 g seats and an airbag, and Diamond gives you a reasonable worst case option for an engine failure in a single engine aircraft. Cirrus offers bleaker options in nearly any scenario other than over water in surface winds less than 24 kts.

This is one of the most important factors that steered me away from Cirrus and toward Diamond when I first started looking for an aircraft a couple of years ago.

[rwtucker]

I read once that a DA40 in a near full "controlled" stall, slowly mushing to the ground, has a descent rate lower than a Cirrus under the parachute. ... Granted, you are still moving forward, and part of the parachute safety is in the beefy Cirrus landing gear built to absorb the impact.
Thoughts about this?

The article was posted on AvWeb: https://www.avweb.com/blogs/insider/AVw ... 652-1.html Basically, in a full stall, the DA40 descends at an average of 900 fpm (varying 600-1,200 fpm) at 48 kt IAS with full directional control, i.e. the capability to steer to an impact point.

Nice to see a report on the forward momentum Rob, although if I had to guess, it seems high for the technique I use. As for descent rate, this may be the descent rate for full hands off (depending on which CG model DA40 you have) but I do it every year with two SOB and varying fuel load (no precision tests). It takes a bit of tweaking (e.g., you are not hands off on the stick; it takes aft pressure plus the trim full aft) but I have never had a descent rate of even 600 FPM. More typically ~500 FPM and sometimes less. I used to get ~900-1200 FPM in my old Dakota with the trim rolled full back, wings level, and with a little extra aft force on the yoke.

[Lou]

At the risk of thread drift, I asked a bunch of veteran northern bush pilots what would they choose to hit in an engine out situation: coniferous (ie spruce) or deciduous. They were unanimous in saying avoid the spruce, which kinda surprised me. The best is willow bushes. Who knew.

And Sara, I have 835

[rwtucker]

More drift: Since I fly over the mountains most of the time, I asked my CFI what he thought about the best approach. He said that if you have to land in the dense forest, pick the best terrain configuration, and try to fly between two trees, if necessary aiming to have the wingtips hit the trees simultaneously, shearing the wings off. He then told me the joke about a student pilot who had that mantra drummed into him during training, only to have an engine failure over the mountains on his long cross-country training flight. After an initial panic, he found two perfectly aligned trees and executed a perfect landing maneuver, shearing the wingtips as he had been taught. He jumped out of the aircraft with no injuries only to notice that he had landed between the only two trees in a relatively flat meadow. Probably an old CFI tale.

[Colin]

This is my favorite DA40 crash, if it is okay to have a favorite. I can't identify the trees, but wish I could.

I also talked to a Trinidad pilot who on his first long, family flight across the country aborted a landing at a small mountain airport and flew the plane into a stand of trees past the runway. Sheared off both wings and dropped the plane, splat, into soft, swampy soil. He, his wife, and daughter walked out.

[N172MZ]

Great info, entertaining too!
Bottom line, fly the plane is always #1.

And now I know why an airbag comes paired with the seatback tray at my nose!

Thanks everyone!

[Don]

Amazing that anyone survived, let alone walking away with just minor injuries. I have seen accident photos of other planes with far less damage but had fatalities involved. I also believe that composite planes have better crash worthiness
than planes constructed from small pieces of aluminum being held together by rivets.