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British 601 Crash (was: 601 Crash)

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pchapman(at)ionsys.com
Guest

Posted: Fri May 11, 2007 9:52 am Post subject: British 601 Crash (was: 601 Crash)

At 13:14 11-05-07, you wrote:



 	  Quote: 	
		  



Just got an email alert of another one that went down in the UK.



Yahoo! Alerts Yahoo! News - My Alerts - Edit Alert

Friday, May 11, 2007 9:10 AM PDT



Wing spar failed in plane crash

Yorkshire Post Today Fri, 11 May 2007 5:25 AM PDT

TWO men who died when a light aircraft plummeted to the ground in a 

ball of flames were the victims of a break in the plane's wing 

structure, a report has revealed. (11/05/2007 10:21:12)


	


Synopsis:

http://www.aaib.dft.gov.uk/publications/bulletins/may_2007/zenair_ch601ul__g_yoxi.cfm

Report:

http://www.aaib.dft.gov.uk/cms_resources/Zenair%20CH601UL,%20G-YOXI%2005-07.pdf



Haven't read it in detail, but they believe a hard pull up from a low 

pass (possibly to avoid wires) was a cause.

Still one can always question how much extra margin one has in any 

airplane. It can be nice if a gap between Yield and Ultimate stress 

allows a pilot to come back home alive, even if the wings are bent...



According to the British AAIB, it was a CH-601 UL, built from a Czech 

Aircraft Works Quick Build kit.



Given the frustration voiced here with the US FAA, over another accident,

it is very interesting to note that the AAIB report provides some 

analysis of the nature of the structural failure, that also includes 

engineering input from the manufacturer.

Peter Chapman

Toronto, ON           601 HDS  /  912  /  C-GZDC

amyvega2005(at)earthlink.
Guest

Posted: Fri May 11, 2007 11:00 am Post subject: British 601 Crash (was: 601 Crash)

I have read the report, and while sad, it is apparent to me, people are getting a little over confident with the plane (pulling the stick back too hard).  The only way for both spars to fold in my opinion is for the pilot to crank it back too hard, which overconfidence can do.  one flys into known IMC, one dodges wires, one supposedly flys short of gas, one flys with known engine problems per the report and the engine blows up,   yet we blame the plane design.

Gott to do some rethinking as a pilot and treat the plane within its design parameters.  Having a high G utility rating, is no excuse to pull hard Gs with full max load. even an extra 300 with high G tolerances, have warnings of flying high Gs manauvers over a certain weight.  Would they fly a censsna 152 the same way?



Juan  



--

JerryHey

Joined: 05 May 2007
Posts: 30

Posted: Fri May 11, 2007 11:19 am Post subject: British 601 Crash (was: 601 Crash)

"pulling back on the stick to hard" should result in a stall (at  

which point the wing unloads) not a wing failure. Am I wrong?     Jerry



On May 11, 2007, at 2:59 PM, Juan Vega wrote:



[quote] 

 <amyvega2005(at)earthlink.net>



 I have read the report, and while sad, it is apparent to me, people  

 are getting a little over confident with the plane (pulling the  

 stick back too hard).  The only way for both spars to fold in my  

 opinion is for the pilot to crank it back too hard, which  

 overconfidence can do.  one flys into known IMC, one dodges wires,  

 one supposedly flys short of gas, one flys with known engine  

 problems per the report and the engine blows up,   yet we blame the  

 plane design.

 Gott to do some rethinking as a pilot and treat the plane within  

 its design parameters.  Having a high G utility rating, is no  

 excuse to pull hard Gs with full max load. even an extra 300 with  

 high G tolerances, have warnings of flying high Gs manauvers over a  

 certain weight.  Would they fly a censsna 152 the same way?



 Juan



 --

p.mulwitz(at)worldnet.att
Guest

Posted: Fri May 11, 2007 11:51 am Post subject: British 601 Crash (was: 601 Crash)

I think it depends on how fast you are going.  The faster you go, the 

harder it is to stall and the more load placed on the airframe when 

you pull up hard.



I think this is part of the design issue when determining Vne.



Paul

XL fuselage

do not archive



At 12:19 PM 5/11/2007, you wrote:



 	  Quote: 	
		  "pulling back on the stick to hard" should result in a stall (at

which point the wing unloads) not a wing failure. Am I wrong?     Jerry

amyvega2005(at)earthlink.
Guest

Posted: Fri May 11, 2007 11:51 am Post subject: British 601 Crash (was: 601 Crash)

You are not wrong, but almost right.   You got to look at the mass of an object relative to it changing direction abruptly.  PLane going straight carrying 1320 Lbs, changes direction suddenly and the mass wants to keep going straight.  If the wings are fully loaded, they can't take the extreme angle so quickly at max load, they will snap like a twig.  same goes for any plane.  remember 15 years ago the Malibu ADs.  Peoople were transitioning from Bonanzas to Malibus and the planes were crashing becuase the wings were snapping of.  When they stopped trying to blame the plane, they looked at the fact that most pilots were not trained in flying the plane at high altitude and the result was pilots exceeding the stresses of the plane at cruise.  How so?  Great example of Mass loads on wings.  The pilots were flying them in high altitudes where special training is needed to fly a plane where the VNE (that speed where the wings want to come off) and stall speed are with 10mph (or less) of each other.  This applies to the plane that wer are all building.  The planes are designed with certain stress envelopes.  Everyone knows the zenith can take a licking and keep on ticking, however, when you go outside of its gross envelope, you are asking for trouble.

It is a tough plane, but I would not crank the stick around with full gas and two people. If it was lighter it would stall, but with more stuff inside it, the wings will start to complain.  We are flying a sport pilot rated arecraft that is robust, not an EXTRA 300.  



Juan



--

agibeaut

Joined: 21 Mar 2007
Posts: 64

Posted: Fri May 11, 2007 12:05 pm Post subject: British 601 Crash (was: 601 Crash)

Yes Jerry, unfortunately you are wrong. With the right

combination of speed, weight at gross, and severe

enough pull-up, the airframe/wing failure will occur

before the stall.



Do not archive.

--- Jerry Hey <jerryhey(at)earthlink.net> wrote:



[quote] 

 <jerryhey(at)earthlink.net>

 

 "pulling back on the stick to hard" should result in

 a stall (at  

 which point the wing unloads) not a wing failure. Am

 I wrong?     Jerry

 

 

 

 On May 11, 2007, at 2:59 PM, Juan Vega wrote:

 

 > 

 > <amyvega2005(at)earthlink.net>

 >

 > I have read the report, and while sad, it is

 apparent to me, people  

 > are getting a little over confident with the plane

 (pulling the  

 > stick back too hard).  The only way for both spars

 to fold in my  

 > opinion is for the pilot to crank it back too

 hard, which  

 > overconfidence can do.  one flys into known IMC,

 one dodges wires,  

 > one supposedly flys short of gas, one flys with

 known engine  

 > problems per the report and the engine blows up,  

 yet we blame the  

 > plane design.

 > Gott to do some rethinking as a pilot and treat

 the plane within  

 > its design parameters.  Having a high G utility

 rating, is no  

 > excuse to pull hard Gs with full max load. even an

 extra 300 with  

 > high G tolerances, have warnings of flying high Gs

 manauvers over a  

 > certain weight.  Would they fly a censsna 152 the

 same way?

 >

 > Juan

 >

 > --

rickpitcher

Joined: 27 Feb 2007
Posts: 76

Posted: Fri May 11, 2007 12:13 pm Post subject: Re: British 601 Crash (was: 601 Crash)

[quote="JerryHey"]"pulling back on the stick to hard" should result in a stall (at  

which point the wing unloads) not a wing failure. Am I wrong?     Jerry

I noticed that we are talking about a 601-"UL" here. 

These are built a lot lighter than the "HD"'s and "XL"'s in order to qualify as an "ultralight" in some Europeon countries. They have a gross weight of 1050 lbs. The "HD" is rated (at)1200 and the "XL" (at) 1320.

If these guys DID pull out too hard while going too fast, the lighter "UL" wing would be the most likely to be overloaded and the first to let go.



Rick

planecrazydld(at)yahoo.co
Guest

Posted: Fri May 11, 2007 12:18 pm Post subject: British 601 Crash (was: 601 Crash)

that is what maneuvering speed is all about...



Jerry Hey <jerryhey(at)earthlink.net> wrote:  [quote]--> Zenith-List message posted by: Jerry Hey 



"pulling back on the stick to hard" should result in a stall (at 

which point the wing unloads) not a wing failure. Am I wrong? Jerry



On May 11, 2007, at 2:59 PM, Juan Vega wrote:



[quote] --> Zenith-List message posted by: Juan Vega 

 



 I have read the report, and while sad, it is apparent to me, people 

 are getting a little over confident with the plane (pulling the 

 stick back too hard). The only way for both spars to fold in my 

 opinion is for the pilot to crank it back too hard, which 

 overconfidence can do. one flys into known IMC, one dodges wires, 

 one supposedly  flys short of gas, one flys with known engine 

 problems per the report and the engine blows up, yet we blame the 

 plane design.

 Gott to do some rethinking as a pilot and treat the plane within 

 its design parameters. Having a high G utility rating, is no 

 excuse to pull hard Gs with full max load. even an extra 300 with 

 high G tolerances, have warnings of flying high Gs manauvers over a 

 certain weight. Would they fly a censsna 152 the same way?



 Juan



 --

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Fri May 11, 2007 8:06 pm Post subject: British 601 Crash (was: 601 Crash)

Not if you are flying faster than maneuvering speed. If the initial 

reports are true, this plane had just performed a diving maneuver to a 

low pass and was probably exceeding Va by a good margin.



Famous last words: "Hey y'all watch this!"



Jerry Hey wrote:

 	  Quote: 	
		   

 

 "pulling back on the stick to hard" should result in a stall (at which 

 point the wing unloads) not a wing failure. Am I wrong?     Jerry

 


	


-- 

Bryan Martin

Zenith 601XL N61BM

Ram Subaru, Stratus redrive

Do Not Archive

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

Scotsman

Joined: 27 Aug 2007
Posts: 89
Location: Johannesburg, South Africa

Posted: Thu Aug 30, 2007 6:27 am Post subject: Re: British 601 Crash (was: 601 Crash)

Is there a difference in the structure of an Xl versus the UL model maybe in the interest of weigh saving to meet the LSA requirements?



j



do not archive

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Wed Sep 05, 2007 6:56 am Post subject: Re: British 601 Crash (was: 601 Crash)

 	  amyvega2005(at)earthlink. wrote: 	
		  If it was lighter it would stall, but with more stuff inside it, the wings will start to complain.  We are flying a sport pilot rated arecraft that is robust, not an EXTRA 300.  



Juan



-- 	




Actually, I'm sure it's even more likely to be stalling at a higher rate of speed, it's just that there's a lot more drag on the wing at higher speeds and that's what's snapping the wings. A lightly loaded plane and a heavily loaded plane, pulled up quickly, will exert just as much stress on the wings, the only difference is the lighter plane will climb 50 or 100 feet while the wings fail where as the heavier plane will just continue in a straight line while the wings break off.

steveadams

Joined: 10 Jan 2006
Posts: 191

Posted: Thu Sep 06, 2007 3:58 am Post subject: Re: British 601 Crash (was: 601 Crash)

A simple way to look at wing loading, G forces, and structural failure point is to bring everything down to a common denominator; load vs. lift. For simplicity, I am just making up numbers, but the concepts are valid. Say you have a 1000lb max gross airplane with structural limit of 6G's. 6G x 1000 = 6000lb on the wings will break them off. Now look at lift. At stall speed at 1G, the max lift generated by the wings = 1000lb. At Va, stall will occur just before we exceed the design load, (for simplicity we'll use the ultimate load, but in practice you would use a more conservative loading). So at Va, stall will occur just before 6G, so the max lift generated by the wings at that speed = just under 6000lb. The faster you go, the more lift the wings generate, therefore going any faster than Va the wings can generate more than 6000 lb of lift. Say you are at Va +10 mph and the wings at that speed produce 10% more lift, therefore, stall will not occur until you load the wings to 6600lbs, far greater than the failure point.

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