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tragic accident

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taffy8706(at)yahoo.com
Guest

Posted: Mon Mar 06, 2006 6:16 pm Post subject: tragic accident

Has anyone heard as to what went wrong to cause this

tragic accident?-------- Fritz

NTSB Identification: LAX06LA105

14 CFR Part 91: General Aviation

Accident occurred Wednesday, February 08, 2006 in

Oakdale, CA

Aircraft: Zenith Aircraft Company Zodiac 601XL,

registration: N105RH

Injuries: 2 Fatal.



This is preliminary information, subject to change,

and may contain errors. Any errors in this report will

be corrected when the final report has been completed.



On February 8, 2006, at 1518 Pacific standard time, an

experimental Zenith Aircraft Company Zodiac 601XL,

broke up in flight and impacted flat open terrain in a

nose down attitude near Oakdale Airport (O27),

Oakdale, California. The pilot/owner operated the

airplane under the provisions of 14 CFR Part 91. The

airplane was destroyed. The private pilot/owner and

the certified flight instructor (CFI) were fatally

injured. Visual meteorological conditions prevailed

for the local area flight that departed Modesto

City-County Airport-Harry Sham Field (MOD), Modesto,

California, about 1500. No flight plan had been filed.



Witnesses, who saw them boarding at Modesto, indicated

that the CFI was seated in the left seat, and the

pilot/owner was seated in the right seat. 



According to witnesses in the area, the airplane

entered the pattern for landing at Oakdale about 1515.

The left wing bent up (perpendicular to the fuselage)

and folded back and the airplane started to spin to

the right. Other witnesses reported that the airplane

completed one full revolution before the right wing

bent up (perpendicular to the fuselage) and folded

back. The airplane's nose pitched down between 60-70

degrees, and impacted the ground. No unusual noises

were heard coming from the engine.



According to a Federal Aviation Administration (FAA)

airworthiness inspector, the airplane was purchased in

Hemet, California. The airplane was delivered to

Modesto on December 15, 2005, where it sat in its

hangar until the day of the accident.

frank.hinde(at)hp.com
Guest

Posted: Tue Mar 07, 2006 7:00 am Post subject: tragic accident

No but isn't this the second example of this happening recently??



I do hope they identify the cause quickly so the entire fleet can be

inspected. Us HD(s) owners had a bunch of wing spar slice plates with

holes too close to the edge...Did'nt hear of any failures due to this

though.



I hope ZAC is all over this one??



Frank



HDS 392 hours...For sale very soon



Do not archive

  



--

todd(at)toddtown.com
Guest

Posted: Tue Mar 07, 2006 7:55 am Post subject: tragic accident

Isn't this the same accident we heard about right after it happened?



Todd Osborne

Internet E-Mail: todd(at)toddtown.com

Web Site: www.toddtown.com

MSN (Windows) Messenger: todd(at)toddtown.com

AOL Instant Messenger: toddosborn(at)aol.com

dredmoody(at)cox.net
Guest

Posted: Tue Mar 07, 2006 9:49 am Post subject: tragic accident

This accident is the same one that was brought up on the list about 5 - 6 

weeks ago. Still it would be good to hear what the cause was.



Ed Moody II

Rayne LA

601XL waiting on kit



Do Not Archive



---

JAPhillipsGA(at)aol.com
Guest

Posted: Tue Mar 07, 2006 10:15 am Post subject: tragic accident

This to all 601XL drivers, based on the description from the eye witness of 

the accident, that the wing folded back, we have been brain storming what would 

have to occur to set that in motion and the hypothesis on first blush is if 

the ONE bolt that attaches the rear wing spar to the bracket on the side of the 

fuselage was to fail or fall out with air pushing and twisting rearward 

against the wing it could fold back perpendicular to the fuselage. Something like a 

Grumman Hellcat parked on a deck. Without any more information I am removing 

my bolts this weekend before I fly again and inspect those bolts and the 

bracket. 

Best regards, Bill N505WP

frank.hinde(at)hp.com
Guest

Posted: Tue Mar 07, 2006 10:31 am Post subject: tragic accident

Out of interest has anyone asked ZAC about what they know about this

accident?



Frank 601HDS



Do not archive 



--

p.mulwitz(at)worldnet.att
Guest

Posted: Tue Mar 07, 2006 10:55 am Post subject: tragic accident

Thanks for this analysis, Bill.



I wonder if anyone has asked Chris about this issue.  It would seem 

easy enough to add additional bolts to the rear spar if this is even 

a remote possibility.



I am not at all qualified to have a significant opinion on anything 

like this, but it seems to me that failure of the main spar or 

perhaps failure of a line of rivets in the skin could also cause the 

wing to fold.



I would really like to know what the NTSB concludes about this 

accident.  I would also like to hear anything Chris Heintz has to say 

on this issue.  I hope someone who has his ear brings this to his 

attention and urges him to speak on this kind of major structural failure.



This is really spooky!



Paul

XL wings



 	  Quote: 	
		    Zenith-List message posted by: JAPhillipsGA(at)aol.com



This to all 601XL drivers, based on the description from the eye witness of

the accident, that the wing folded back, we have been brain storming 

what would

have to occur to set that in motion and the hypothesis on first blush is if

the ONE bolt that attaches the rear wing spar to the bracket on the 

side of the

fuselage was to fail or fall out with air pushing and twisting rearward

against the wing it could fold back perpendicular to the fuselage. 

Something like a

Grumman Hellcat parked on a deck. Without any more information I am removing

my bolts this weekend before I fly again and inspect those bolts and the

bracket.

Best regards, Bill N505WP


	


---------------------------------------------

Paul Mulwitz

32013 NE Dial Road

Camas, WA 98607

---------------------------------------------

dougsire

Joined: 10 Jan 2006
Posts: 37

Posted: Tue Mar 07, 2006 12:18 pm Post subject: Tragic Accident

I'm thinking some of the circumstances surrounding the flight seem a bit odd.

-The NTSB report states that the aircraft was delivered on 12/15/05 and

sat in a hanger until the day of the flight/accident.  So, this was

apparently the first flight by the new owner, and he had an instructor as

PIC (how much did these two weigh?).   He may not have had any familiarity

with the aircraft.

-It appeared to be a nice day; winds were only three knots with good

visibility.

-The flight only lasted 15 minutes.

-Since they were approaching to land, their airspped was slow.



So, it doesn't look like an accident that could have been caused by any

severe aerodynamics stress on the airframe.   I'm wondering how the owner

took delivery.   Were the wings removed and then the aircraft was shipped

to the buyer?   Maybe the wing spar bolts were not all replaced.   Maybe

they were removed for inspection and not replaced.   Why didn't the

airplane fly for about two months after delivery?



If this was a first flight, you would think it would have lasted more than

15 minutes.   Possibly the pilot felt that something didn't feel right

(loose wings) after takeoff and was returning to check it out.



It is also entirely possible that the eyewitness accounts got it wrong and

it was just an approach to landing stall that was the result of a first

flight unfamiliarity with the aircraft.   Eyewitnesses can often be very

unreliable.



I doubt it will prove to be a reflection on the quality of the design.



Doug Sire

601XL

_________________
Doug Sire 601XL
Do Not Archive

frank.hinde(at)hp.com
Guest

Posted: Tue Mar 07, 2006 12:47 pm Post subject: Tragic Accident

I assume the wing attach uses the tired and trusted spar slice plates

and single bolt at the rear spar. I do know some examples of the HD(S)

had problems with the rear attach cracking but I never heard of one

failing catastrophically.



Definatly a weired one but I agree with you Doug I doubt it's a design

flaw but I do hope the results are made VERY public.



Makes you think though, I am working on the RV7 and thought I had

tightened all the oil lines to the invert system....Nope they are still

finger tight as are the prop bolts. I could see how a critical fastener

could be missed.



Frank



Do not archive



--

ggower_99(at)yahoo.com
Guest

Posted: Tue Mar 07, 2006 9:02 pm Post subject: tragic accident

Yes, is the same one,  I think we all have to wait for the FAA  (NTBS?)  final report to posible know what happened,  every other possiblity will only be wild thinking now.

   

  Saludos

  Gary Gower.

  



Todd Osborne <todd(at)toddtown.com> wrote:

  



Isn't this the same accident we heard about right after it happened?



Todd Osborne

Internet E-Mail: todd(at)toddtown.com

Web Site: www.toddtown.com

MSN (Windows) Messenger: todd(at)toddtown.com

AOL Instant Messenger: toddosborn(at)aol.com

		

---------------------------------

Bring photos to life! New PhotoMail  makes sharing a breeze.

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Mar 08, 2006 3:49 am Post subject: Tragic Accident

On the XL, the outer spar root ends fit in between the two vertical webs of

the center spar and six bolts pass through the spar cap extrusions. There

are no splice plates. There is one bolt holding the rear spar to the rear

frame. I can't imagine how the wing could fold up at that joint unless bolts

were left out.

-- 

Bryan Martin

N61BM, CH 601 XL, Stratus Subaru.

on 3/7/06 3:45 PM, Hinde, Frank George (Corvallis) at frank.hinde(at)hp.com

wrote:



 	  Quote: 	
		   

 <frank.hinde(at)hp.com>

 

 I assume the wing attach uses the tired and trusted spar slice plates

 and single bolt at the rear spar. I do know some examples of the HD(S)

 had problems with the rear attach cracking but I never heard of one

 failing catastrophically.

 

 Definatly a weired one but I agree with you Doug I doubt it's a design

 flaw but I do hope the results are made VERY public.

 

 Makes you think though, I am working on the RV7 and thought I had

 tightened all the oil lines to the invert system....Nope they are still

 finger tight as are the prop bolts. I could see how a critical fastener

 could be missed.

 

 Frank

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

BillHowerton
Guest

Posted: Wed Mar 08, 2006 5:51 am Post subject: Tragic Accident

Was out at the hangar the other night thinking about this one... My XL's wings are nearly complete, as is the fuselage, so I really looked inside the center spar/wing spar attachment point.



It seems to me that it would be very difficult for this to be a situation where someone left out the spar bolts, or failed to tighten them.  Even if the nuts had indeed come loose, the bolts would had to have worked their way out of their holes - something that seems unlikely to have occurred with a wing under load -- the load itself would have kept them inplace.  But assuming that it did happen, or that the bolts were omitted entirely, for the wing to fold up, it would have to come out of the center spar enough to clear the bottom of the center spar cap.  The only way this can happen is if the rear bolt also came out to allow the wing to move horizontally  away from the fuselage.  In other words it would pretty much require that the spar bolts be omitted AND that the rear bolt either failed, came loose or it too was omitted.  While I guess it's possible someone could be that negligent, it seems unlikely that anyone could be that stupid.



It seems to me the more likely scenario is that they experienced some kind  of structural failure.   Trying to fit the eye-witness accounts with the design, the only way I can see this occurring would have to have been a crack in the lower section of the spar itself that had been unnoticed during assembly, and manifested itself and grew when the wing was placed under load.  If this happened the wing could indeed fold up, and the rear channel would simply rotate, with the rear bolt acting as a pivot point.  This could be the result of corrosion, or perhaps from a scratch that went un-heeded.  We know that the owner had recently taken delivery, but we don't know under what circumstances he came to own the plane, nor do we know how long or under what conditions that the wing sat before being assembled.

  ---

n801bh(at)netzero.com
Guest

Posted: Wed Mar 08, 2006 6:32 am Post subject: Tragic Accident

There is the good chance they were out doing aerobatics and overstressed the plane, realized they did tweak something and were limping back to the airport before something major failed. I doubt they would have made a radio call stating to the effect of that senerio. All it would have taken was a turbulance bump down low where they are the strongest while decending into the pattern to land to have the wing fail completely. I will bet the NTSB will figure this thing out.

Godspeed to those two guys..................................

 

do not archive



Ben Haas

N801BH

www.haaspowerair.com





There is the good chance they were out doing aerobatics and overstressed the plane, realized they didtweak something and were limping back to the airport before something major failed. I doubt they would have made a radio call stating to the effect of that senerio. All it would have taken was a turbulance bump down low where they are the strongestwhile decending into the pattern to land to have the wing fail completely. I will bet the NTSB will figure this thing out.





Godspeed to those two guys..................................



do not archive



BenHaas

N801BH

www.haaspowerair.com

rick.tedford(at)sympatico
Guest

Posted: Fri Mar 10, 2006 4:11 pm Post subject: Tragic accident

I am sorry . I should have said Do not archive

Best regards

Rick

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