LSA Crashworthiness

[CT4ME]

AVWeb Article on LSA Crashworthiness

AVWeb, and Paul Bertorelli, usually gets it right. But I think they've missed it this time. In the above article, Paul tries to make the point that Light Sport Aircraft are basically un-crashworthy, with the argument that no 1320 lb MTOW aircraft could be built well enough to be "crashworthy". He opines that they don't have enough space to "flail about", and that the materials are not strong enough. In his words: "LSAs and real crashworthiness are mutually exclusive".

I, for one, am proud of the apparent crashworthiness of the CT line of aircraft. I'm constantly amazed at how well the CT holds up in crash situations.

Read the article... if you disagree, be sure to leave a comment.

Tim

[Runtoeat]

Tim, the recent crash of a CTLS at Hillsdale, Michigan, resulted in the pilot calling back to Hillsdale FBO on his cell phone requesting help after removing himself from the plane. He ended up with a cut on his head and some scratches but did not require hospitalization. This aircraft struck trees while still under power doing a low pass at a grass field. Both wings were torn off, with one wing remaining in the tree. The plane ended up on it's side in the middle of a gravel country road. A few years ago, I walked around the crumpled remains of another CTLS which had an engine out and made a forced landing in a grass field in Ohio. The plane went into a 7 foot ditch which ripped the main landing gear off, tore the wings backward and dislodged the engine and front landing gear and popped out the windshield. Both the pilot and passenger of this plane also walked away. There are other crashes of Flight Design aircraft which have been in the news and I do not recall hearing of any deaths but this is only my recollection and not factual accounts. It appears that the "egg" shape of the CTSW and CTLS cockpit structure which is made from graphite and kevlar fiber appears to be extremely strong and provides crashworthyness that is "state of the art" for high performance aircraft and racing vehicles, Besides the crashworthyness of the CT, this aircraft and many other LSA aircraft also provide, either thru optional selection or as part of the standard package, a ballistic recovery system (parachute) which enhances the crash survivability of these aircraft.

[FredG]

I saw nothing in Paul B's AVWeb article that represented a serious technical assessment of LSA crashworthiness.

 

Like Dick, above, I am very satisfied with the safety and crashworthiness of my CTsw. But, lets remember, we don't have a lot of data and while anecdotes of crash survival are comforting, they are not scientifically reliable. Systematic surveillance of crashes and resulting injury is the most robust approach to understanding what is a risk and what is protective.

[johngpilot]

If anyone wants to send me a message I can provide a PDF document produced at Flight Design that shows the design characteristics/of the Safety Cell on the CTLS.

 

It is called "CT Safety Cabin Design".

 

It talks about the load transfers and how they are like modern cars and done so that crash loads transfer through the passenger area to the crush-zones in the vehicle. The cabin remains stable while the energy is absorbed in the peripheral areas.

[Jim Meade]

I agree he wrote what I would call a frilly or frothy piece. Lot's of emotion, not much fact. I left a comment as have others on this board and elsewhere.

 

His are the kinds of perceptions we will always face in LSA. To some extent, I ignore them. If I can correct something, I will, but it may not be worht the effort to me to get in a long discussion with someone who has already made up his mind. With him, I felt it important to at least register my dissent because he has a reputation for credibility in some circles.

 

Thanks for pointing out the article.

 

 

[knolde]

AVWeb Article on LSA Crashworthiness

AVWeb, and Paul Bertorelli, usually gets it right. But I think they've missed it this time. In the above article, Paul tries to make the point that Light Sport Aircraft are basically un-crashworthy, with the argument that no 1320 lb MTOW aircraft could be built well enough to be "crashworthy". He opines that they don't have enough space to "flail about", and that the materials are not strong enough. In his words: "LSAs and real crashworthiness are mutually exclusive".

I, for one, am proud of the apparent crashworthiness of the CT line of aircraft. I'm constantly amazed at how well the CT holds up in crash situations.

Read the article... if you disagree, be sure to leave a comment.

Tim

 

I also read the Bertorelli article and I am amazed at his lack of understanding about LSA's and how well they seem to stay together in moments of stress--fancy way of saying I have had two major accidents. First, I had a hanger blow down in a wind storm and much of it landed on my CT. While the plane was damaged severely, had Nancy and I been in the plane at the time--we would have been fine. The cabin integrity had not been breeched. Second was our taxing into a ditch (dark) that was neither notamed or marked with a sign or light. The only problem we saw at the time was that the taxi light would not work. Six weeks later it was discovered that the motor mount failed and the engine slipped down causing extensive structural damage. Again, the cabin was not affected and the fact that we flew the airplane for six weeks with serious damage indicated a pretty secure structure. Aside from the CTs, we see many other LSA survive crashes with crew survival. Nancy, my white knuckle flying wife read the article and said "he seems not to know much about our airplane." She may not be an aviation wizz, but she flies with me because she feels safe with our CT (and me). Bottom line for me on the article is that it is a miss and I have dismissed it.

 

 

See ya, Ken and Nancy Nolde, N840KN 500+ fun hours and looking for many more, in our CTLS!

[chanik]

I found that article missed the point on two levels. First because it was such a fetid pile of unresearched guesswork and second because statistically speaking crashworthiness is incidental to most serious accidents. Read though the last few years of Nall reports and you'll see that most fatal accidents ~80% are planes drilling into the ground. Add takeoff stalls with approach spins with maneuvering flight (biggest category) then add death spirals in IMC. Even many of the ones categorized in mechanical failures (10%) if you read the NTSB ultimately involve distracted pilots forgetting about that stall/spin thing at 200ft as they try for an emergency landing. ~30% of fatal accidents end up uncategorized; why? There is nothing but a crater to examine. Whatever the proximate cause, it is hard to argue virtually all of those had some poor pilotage as the ultimate cause. What Leighton Collins said in Stick and Rudder in 1944! is still true today, even the ratio: at least 70% of fatalities are pilots losing control of their airplanes, usually close to the ground. From an engineering standpoint, it doesn't matter whether due to poor decision making or flying skill. Designing a structure for survivability from 100+ MPH sudden deceleration is practically impossible.

 

What we really need in GA is more crash-wary pilots not crashworthy planes. On the vehicle side, the cost effective issue to address would be stall/spin resistance. I've tried accelerated stalls quickly returning to wings level from 45deg and the CT is very forgiving even when mildly cross controlled (the biggest pattern flight killer). The plane fishtails around alot though, sort of a big clue you're doing something wrong. The Cirrus, Mooney and Lancair sort of high performance wings will break abruptly and consequently have very high fatality rates, 4x that of Diamond DA40s and Cessna 172s even though the Cirrus has the chute. Not much use to a stunned pilot suddenly spinning at 500ft. http://www.cirruspilots.org/media/p/621587.aspx

Funny but in Stick and Rudder they predicted in a few years GA planes wouldn't even have separate rudder controls, like the ercoupe, so pilots couldn't get into these problems easily.