---------------------------------------------------------- Zenith601-List Digest Archive --- Total Messages Posted Fri 10/30/09: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:24 AM - Re: Flying Times (The Minearts) 2. 06:32 AM - Re: NTSB letter and flutter. (Gig Giacona) 3. 07:24 AM - Re: Re: NTSB letter and flutter. (Paul Mulwitz) 4. 08:54 AM - Re: Additional NTSB Documents (Stephen Smith) 5. 09:15 AM - Re: Flying Times (KC7HFA) 6. 11:10 AM - Re: Re: Additional NTSB Documents (Terry Turnquist) 7. 12:51 PM - Re: Additional NTSB Documents (Sabrina) 8. 12:54 PM - Re: Re: Additional NTSB Documents (Greg Cox) 9. 04:13 PM - rear spar reinforcement (paul baker) 10. 04:26 PM - Re: Additional NTSB Documents (sonar1@cox.net) 11. 08:09 PM - Re: Additional NTSB Documents (John Smith) ________________________________ Message 1 _____________________________________ Time: 04:24:23 AM PST US From: "The Minearts" Subject: Zenith601-List: Re: Flying Times N164SM has been flown approximately 10 of her first 18 hours this year, since 7/30 has been down for installation of a Gold Oil system and Weseman 5th Bearing kit, now ready to resume flying. Steve Mineart CH-601XL/ WW Corvair ________________________________ Message 2 _____________________________________ Time: 06:32:09 AM PST US Subject: Zenith601-List: Re: NTSB letter and flutter. From: "Gig Giacona" psm(at)att.net wrote: > > > The letter itself says: "It appears . . .flutter . . . likely source". This is a country mile away from a statement that flutter caused the accidents. It is merely a conjecture that is presented for further consideration and testing. > > Paul > XL awaiting engineering changes > > - Well the same letter also said this, "There is substantial circumstantial evidence that flutter occurred in some, if not all, of the above-cited accidents." Which about a city inch from saying flutter was the cause. -------- W.R. "Gig" Giacona 601XL Under Construction See my progress at www.peoamerica.net/N601WR Read this topic online here: http://forums.matronics.com/viewtopic.php?p=270102#270102 ________________________________ Message 3 _____________________________________ Time: 07:24:26 AM PST US From: Paul Mulwitz Subject: Re: Zenith601-List: Re: NTSB letter and flutter. It is an unfortunate truth that there are many different ways to interpret complex statements in our language. For people whose reading is primarily entertainment/literature or newspaper articles it is useful to ignore many of the words in each sentence to get the core meaning. In technical writings this will lead you down the wrong path. If you ignore the qualification that the "Evidence" is substantial and circumstantial in "substantial circumstantial evidence" and you already hold the belief that flutter is behind the accidents then that statement can be comforting. However, if the writer really believed there was enough evidence to establish the fact he would not have used the qualifications of "Substantial" and "Circumstantial" in his statement. This removes his assertion two different times from a direct statement.. He is really saying (in technical jargon) flutter is a candidate for the cause of the accidents. However there is no actual evidence but there is circumstantial suggestion that supports this notion. In addition, the circumstantial evidence isn't really consistent but only somewhat supporting the notion which means it is substantial rather than convincing. He further reduces the confidence by referring to "Some" of the accidents instead of "All" of them. Just like the opening paragraph of the letter, the writer uses two qualifying phrases to limit his confidence in the statement that flutter is behind the accidents. Once again the statement is an argument for further study rather than a definitive assertion. I have heard comments that the ZBAG group reached the conclusion that flutter was the cause of all the problems with Zodiac XLs and somehow got the NTSB to consider this conclusion. For them, the NTSB letter can provide support for their conclusion. For someone who carefully reads the NTSB letter without already being convinced of the flutter argument the letter says just the opposite thing. It allows for the possibility that flutter is the cause but carefully refrains from actually supporting that conclusion. What the NTSB letter is crystal clear about - with no qualifying language at all - is that there have been a lot of fatal accidents and the fleet should be grounded. Paul XL awaiting engineering changes At 06:31 AM 10/30/2009, you wrote: >psm(at)att.net wrote: > > The letter itself says: "It appears . . .flutter . . . likely > source". This is a country mile away from a statement that flutter > caused the accidents. It is merely a conjecture that is presented > for further consideration and testing. > > > > Paul > > XL awaiting engineering changes > > > > - > >Well the same letter also said this, "There is substantial >circumstantial evidence that flutter occurred in some, if not all, >of the above-cited accidents." Which about a city inch from saying >flutter was the cause. ________________________________ Message 4 _____________________________________ Time: 08:54:30 AM PST US Subject: Zenith601-List: Re: Additional NTSB Documents From: "Stephen Smith" Interesting information. The location of failure is for sure a weak spot on the wing. I noted this weakness before my plane even flew. I always thought it odd that such a large hole would be placed in a critical component but I figured someone knew that it was OK; maybe not... The PDFs are careful not to say the deformation occurred in flight. They even suggest that the deformation may have occurred on impact. However should the deformation occur in flight the aileron and flap would lock together so that the aileron would no longer move. A crash would result without a doubt. I have looked at the PDFs three times. I conclude that if the NTSB knew what the deformation "meant" in the crash investigation, they would say something more definitive. I think this is a symptom, not a cause; probably not interesting nor an area to fix on our planes. I would not fault anyone for adding a bit a aluminum in that spot to make it stronger however. I wonder what the 650 looks like in this area. Steve -------- Steve Smith N601WF Zenair Zodiac XL Jabiru 3300 600+ hours Sensenich composite - ground adjustable Read this topic online here: http://forums.matronics.com/viewtopic.php?p=270120#270120 ________________________________ Message 5 _____________________________________ Time: 09:15:43 AM PST US Subject: Zenith601-List: Re: Flying Times From: "KC7HFA" I've put on 26 hours since March 2009. The flight down to Quality Sport Planes (in Cloverdale Ca) fly-in this October was great! -------- Ron Asbill N601ZX - CH-601 XL Jabiru 3300 Completed and Flying!~ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=270128#270128 ________________________________ Message 6 _____________________________________ Time: 11:10:48 AM PST US From: Terry Turnquist Subject: Re: Zenith601-List: Re: Additional NTSB Documents This is what I did to beef up that area. I'm not advocating this for anyone else..use your own discretion.Terry Turnquist ----- Original Message ---- From: Stephen Smith Sent: Fri, October 30, 2009 10:54:17 AM Subject: Zenith601-List: Re: Additional NTSB Documents Interesting information. The location of failure is for sure a weak spot on the wing. I noted this weakness before my plane even flew. I always thought it odd that such a large hole would be placed in a critical component but I figured someone knew that it was OK; maybe not... The PDFs are careful not to say the deformation occurred in flight. They even suggest that the deformation may have occurred on impact. However should the deformation occur in flight the aileron and flap would lock together so that the aileron would no longer move. A crash would result without a doubt. I have looked at the PDFs three times. I conclude that if the NTSB knew what the deformation "meant" in the crash investigation, they would say something more definitive. I think this is a symptom, not a cause; probably not interesting nor an area to fix on our planes. I would not fault anyone for adding a bit a aluminum in that spot to make it stronger however. I wonder what the 650 looks like in this area. Steve -------- Steve Smith N601WF Zenair Zodiac XL Jabiru 3300 600+ hours Sensenich composite - ground adjustable Read this topic online here: http://forums.matronics.com/viewtopic.php?p=270120#270120 ________________________________ Message 7 _____________________________________ Time: 12:51:58 PM PST US Subject: Zenith601-List: Re: Additional NTSB Documents From: "Sabrina" With respect to 6-W-7, I drilled a 25mm aileron control rod hole rather than a 38mm hole. I drilled the 25mm hole 100mm outboard of RR7 rather than 92mm I placed the BOTTOM (not the center) of the hole 20mm from the lower edge. With respect to 6-W-6, I drilled the Aileron Bellcrank support pivot hole 24 mm from the lower surface, rather than 20. I used 1 1/4" rather than 1" angle. This bellcrank support then rests on an .040 doubler rather than directly on the rib. If you center a 38mm diameter hole 20mm from the bottom, per plans, you have compromised the rear spar. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=270149#270149 ________________________________ Message 8 _____________________________________ Time: 12:54:43 PM PST US From: "Greg Cox" Subject: RE: Zenith601-List: Re: Additional NTSB Documents The rear spar on a CH650 has this hole positioned 92mm outboard of RR#7 and 20mm up from the bottom radius. The hole is 38mm OD and therefore we have 2mm edge distance to the bottom radius and is 36% of the 106m rear spar web. Is it necessary that this hole be so large or could it be reduced? Greg Cox Zenith Zodiac CH650, VH-ZDC Sydney, Australia (Cecil Hills) -----Original Message----- From: owner-zenith601-list-server@matronics.com [mailto:owner-zenith601-list-server@matronics.com] On Behalf Of Stephen Smith Sent: Saturday, 31 October 2009 2:54 AM Subject: Zenith601-List: Re: Additional NTSB Documents Interesting information. The location of failure is for sure a weak spot on the wing. I noted this weakness before my plane even flew. I always thought it odd that such a large hole would be placed in a critical component but I figured someone knew that it was OK; maybe not... The PDFs are careful not to say the deformation occurred in flight. They even suggest that the deformation may have occurred on impact. However should the deformation occur in flight the aileron and flap would lock together so that the aileron would no longer move. A crash would result without a doubt. I have looked at the PDFs three times. I conclude that if the NTSB knew what the deformation "meant" in the crash investigation, they would say something more definitive. I think this is a symptom, not a cause; probably not interesting nor an area to fix on our planes. I would not fault anyone for adding a bit a aluminum in that spot to make it stronger however. I wonder what the 650 looks like in this area. Steve -------- Steve Smith N601WF Zenair Zodiac XL Jabiru 3300 600+ hours Sensenich composite - ground adjustable Read this topic online here: http://forums.matronics.com/viewtopic.php?p=270120#270120 ________________________________ Message 9 _____________________________________ Time: 04:13:19 PM PST US From: "paul baker" Subject: Zenith601-List: rear spar reinforcement After looking at the pictures of the wing failures, I am glad I made a simple reinforcement of the rear spar where the pushrod goes through the spar.The hole is rather large and is very close to the bottom spar cap. I have flown 100 hrs so far this year and I always fly within the limitations of the airplane. After 61 years of flying I find It is best to read the book and do what it says.You can find the attachment at http:/members.cox.net/n601ge/drawings/rearspar.html It is well written and very easy to do. paul baker cfi ________________________________ Message 10 ____________________________________ Time: 04:26:38 PM PST US Subject: Zenith601-List: Re: Additional NTSB Documents From: "sonar1@cox.net" I didn't like the looks of this hole when I built my 601, but didn't make any changes. I am actually happy that this inspector has followed up on this. Seems that this could be a problem especially with any quick aileron inputs with the piano-hinged ailerons. This is certainly a lot easier to fix than counter-weights on the ailerons. The strength is in the top and bottom (like an I beam) so an extra plate on the top and bottom of the wing would be all that would be required. Fred Sanford...N9601.... Read this topic online here: http://forums.matronics.com/viewtopic.php?p=270178#270178 ________________________________ Message 11 ____________________________________ Time: 08:09:44 PM PST US From: John Smith Subject: Zenith601-List: Re: Additional NTSB Documents I used the leftover outboard-rear spar cut-off to "double-up" the rear sp ar aileron rod hole area.- The holes do not need to be that large but the y need to be close to the bottom of the rear spars to clear the aileron rod s.=0A=0A=0A ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message zenith601-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Zenith601-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/zenith601-list Browse Digests http://www.matronics.com/digest/zenith601-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.