KIS-List Digest Archive

Mon 12/15/14


Total Messages Posted: 3



Today's Message Index:
----------------------
 
     1. 09:08 AM - Re: TR-1 Incident down under (Mike Pienaar)
     2. 01:04 PM - Re: TR-1 Incident down under (Scott Stearns)
     3. 08:45 PM - Bolt Preload (Owen Baker)
 
 
 


Message 1


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    Time: 09:08:08 AM PST US
    From: "Mike Pienaar" <mjpienaar@shaw.ca>
    Subject: Re: TR-1 Incident down under
    Thanks Scott, What do you mean by "they allow the bolts to be properly preloaded" Thanks for your help Mike ----- Original Message ----- From: Scott Stearns To: kis-list@matronics.com Sent: Sunday, December 14, 2014 4:21 PM Subject: Re: KIS-List: TR-1 Incident down under Yes, but grove does not make a 1.25" version so you would have to make a 0.25" spacer. Scott ------------------------------------------------------------------------- ----- From: Mike Pienaar <mjpienaar@shaw.ca> To: kis-list@matronics.com Sent: Monday, December 8, 2014 4:49 PM Subject: Re: KIS-List: TR-1 Incident down under Hi Scott Would you recommend these gear installation blocks for the TR4 as well? Thanks Mike ----- Original Message ----- From: "Scott Stearns" <sstearns2@yahoo.com> To: <kis-list@matronics.com> Sent: Thursday, November 27, 2014 11:58 AM Subject: Re: KIS-List: TR-1 Incident down under > > I would recommend updating the gear installation using these gear blocks. > The blocks allow the gear to flex without affecting the bolts and they > allow the bolts to be properly preloaded. > > http://www.groveaircraft.com/radiusplates.html > > Scott > >> On Nov 26, 2014, at 6:38 AM, "mark_trickel" <marktrickel@gmail.com> >> wrote: >> <marktrickel@gmail.com> >> >> KIS Incident Down Under >> >> With regret, I post this news from Australia - Michael Patten=99s TR-1 main >> gear collapsed during roll out after touchdown when one of the attach >> bolts let lose: >> >> Airframe event involving a Amateur Built Aircraft KIS TR-1, VH-AIG, >> Taree, Aerodrome, NSW on 9 September 1996. >> Following an uneventful flight, the pilot reported that the aircraft >> touched down normally. After rolling about 80 m the right wing dropped >> and the pilot suspected a tire had failed. But about 50 m further on he >> heard pronounced scraping noises and the aircraft slewed right then left >> before finally coming to a halt about 10 m to the left of the runway. A >> subsequent inspection of the aircraft revealed that the fixed landing >> gear attachment bolts had failed at the countersunk heads. The failure >> faces contained rust deposits, indicating the bolts had been cracked for >> some time prior to the accident. The manufacturer has subsequently >> changed the design specification to fit standard flat head bolts in place >> of countersunk bolts. >> >> The complete report is located here: >> http://www.atsb.gov.au/publications/investigation_reports/1996/aair/19960 2857.aspx >> >> I ran out to my hanger/shed, and checked mine (my TR-1C is a very early >> kit #23), it has the round Allen head bolts which are recessed into the >> attach bracket =93 I will be checking them for any signs of corrosion or >> cracking, and I recommend you check yours too. Can anybody confirm that >> there was a change to a counter sunk flat head bolt??? Galin =93 while you >> are down for repairs you may want to consider replacing these main gear >> bolts. >> >> Mark T. >> >> >> >> >> Read this topic online here: >> >> http://forums.matronics.com/viewtopic.php?p=434702#434702 >> >> >> >> >> >> >> >> >>-> hbsp; ========================h ttp://www.matronics.com/Navigator?KIS-List<; http://forums.====================


    Message 2


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    Time: 01:04:56 PM PST US
    From: Scott Stearns <sstearns2@yahoo.com>
    Subject: Re: TR-1 Incident down under
    Hi Mike, The proper use of a bolt is to=C2-clamp parts directly together. =C2-Pr eloading a bolt is what we really do when we tighten a nut down to a certai n torque value. =C2-The bolt stretches as you tighten the nut and the bol t provides a constant clamping force (preload) as long the load on the join t never exceeds the clamping force provided by preloaded bolt. =C2-=C2- A great example is the bolts that clamp the main rod bearings around the cr ankshaft of an engine. =C2-Lycoming is very specific on the procedure for torquing these bolts right down to specifying a specific thread lubricatio n fluid. =C2-You can imagine if half the nut torque is going into moving a burr through the threads and not into stretching the bolt then you will n ot get the correct bolt preload. =C2- In this case the joint will not be clamped together with a load greater than the load from moving the piston a nd the joint will open slightly and stretch the bolt with each load applica tion. Now the load on the bolt is cycling instead of the bolt being under a constant preload keeping the joint clamped together. =C2-Eventually the bolt will fatigue and fail. =C2-As I recall this is what happened to the 400 hour since factory new engine in the original factory demo Cruiser lead ing to an off field landing. =C2- The landing gear bolts of course do not go through anywhere near the load c ycles that the main bearing bolts do, but it is still good engineering to h ave bolted joints under a constant preload rather than cycling with every l oad cycle. =C2-This=C2-requires a continuous joint and not leaving any part of the bolt in the open air as in the factory landing gear installatio n. Here is a picture of my landing gear installation on my TR-1. =C2-The bol ts clamp the steel plate onto the flox pads and allow the bolts to be under a constant preload. =C2-The grove parts are a better option today though since they have a built in radius that allows the gear to flex so you don' t need the rubber pad. =C2- The rubber pad goes around the landing gear a nd not under the bolts. =C2-http://www.kisbuild.r-a-reed-assoc.com/KIS-TR 1-Web/ScottSterns/landinggear1.JPG | =C2- | | =C2- | | =C2- | =C2- | =C2- | =C2- | =C2- | | | | | | View on www.kisbuild.r-a-reed... | Preview by Yahoo | | | | =C2- | =C2-Anyhow, this was probably more than you were asking for, but I hope it helps. Cheers,Scott From: Mike Pienaar <mjpienaar@shaw.ca> To: kis-list@matronics.com Sent: Sunday, December 14, 2014 5:54 PM Subject: Re: KIS-List: TR-1 Incident down under Thanks Scott, =C2-What do you mean by "they allow the bolts to be proper ly preloaded"=C2-Thanks for your help=C2-Mike=C2-=C2- =C2- ----- Original Message ----- From: Scott Stearns To: kis-list@matronics. com Sent: Sunday, December 14, 2014 4:21 PM Subject: Re: KIS-List: TR-1 In cident down under Yes, but grove does not make a 1.25" version so you would have to=C2-ma ke a 0.25" spacer. Scott From: Mike Pienaar <mjpienaar@shaw.ca> Sent: Monday, December 8, 2014 4:49 PM Subject: Re: KIS-List: TR-1 Incident down under Hi Scott Would you recommend these gear installation blocks for the TR4 as well? Thanks Mike ----- Original Message ----- From: "Scott Stearns" <sstearns2@yahoo.com> Sent: Thursday, November 27, 2014 11:58 AM Subject: Re: KIS-List: TR-1 Incident down under > > I would recommend updating the gear installation using these gear blocks. > The blocks allow the gear to flex without affecting the bolts and they > allow the bolts to be properly preloaded. > > http://www.groveaircraft.com/radiusplates.html > > Scott > >> On Nov 26, 2014, at 6:38 AM, "mark_trickel" <marktrickel@gmail.com> >> wrote: >> >> >> KIS Incident Down Under >> >> With regret, I post this news from Australia - Michael Patten=99s TR-1 main >> gear collapsed during roll out after touchdown when one of the attach >> bolts let lose: >> >> Airframe event involving a Amateur Built Aircraft KIS TR-1, VH-AIG, >> Taree, Aerodrome, NSW on 9 September 1996. >> Following an uneventful flight, the pilot reported that the aircraft >> touched down normally. After rolling about 80 m the right wing dropped >> and the pilot suspected a tire had failed. But about 50 m further on he >> heard pronounced scraping noises and the aircraft slewed right then left >> before finally coming to a halt about 10 m to the left of the runway. A >> subsequent inspection of the aircraft revealed that the fixed landing >> gear attachment bolts had failed at the countersunk heads. The failure >> faces contained rust deposits, indicating the bolts had been cracked for >> some time prior to the accident. The manufacturer has subsequently >> changed the design specification to fit standard flat head bolts in plac e >> of countersunk bolts. >> >> The complete report is located here: >> http://www.atsb.gov.au/publications/investigation_reports/1996/aair/1996 02857.aspx >> >> I ran out to my hanger/shed, and checked mine (my TR-1C is a very early >> kit #23), it has the round Allen head bolts which are recessed into the >> attach bracket =93 I will be checking them for any signs of corros ion or >> cracking, and I recommend you check yours too. Can anybody confirm that >> there was a change to a counter sunk flat head bolt???=C2- Galin =93 while you >> are down for repairs you may want to consider replacing these main gear >> bolts. >> >> Mark T. >> >> >> >> >> Read this topic online here: >> >> http://forums.matronics.com/viewtopic.php?p=434702#434702 >> >> >> >> >> >> >> >> >>-> hbsp; =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- ====================== == http://www.matronics.com/Navigator?KIS-List<; http://forums.== ================== href="http://www.aeroelectric.com">www.aeroelectric.com href="http://www.buildersbooks.com">www.buildersbooks.com href="http://www.homebuilthelp.com">www.homebuilthelp.com href="http://www.mypilotstore.com">www.mypilotstore.com href="http://www.mrrace.com">www.mrrace.com href="http://www.matronics.com/contribution">http://www.matronics.com/chr ef="http://www.matronics.com/Navigator?KIS-List">http://www.matronics.com /Navigator?KIS-List href="http://forums.matronics.com">http://forums.matronics.com


    Message 3


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    Time: 08:45:35 PM PST US
    From: "Owen Baker " <bakerocb@cox.net>
    Subject: Bolt Preload
    12/15/2014 Hello Scott, Thank you for your very pertinent posted comments on bolt preloads copied below. Please allow me to pick some nits / raise some questions. You wrote: 1) This requires a continuous joint and not leaving any part of the bolt in the open air as in the factory landing gear installation." I either don't understand or I disagree with the above statement. In a normal installation the pre load tension force on the bolt is applied at two locations, the bolt head and the nut, normally by rotating the nut while holding the bolt head from rotating. The entire length of the bolt between those two points is then loaded to a certain stress level created by the torque that has been applied to the nut. Obviously there must be some material (the items being held together by the bolt) that prevents the nut from being rotated until it contacts the bolt head. But that stacked up material (usually a minimum of two pieces with maybe some additional pieces being squeezed between them) does not need to extend along and cover the entire length of the bolt, from nut to bolt head, when proper torqueing of the nut is completed. An air gap in the stack up will not, by itself, prevent a proper bolt preload from being created. Such an air gap exists even in your stack up and can be seen in the photo in your original email where the bolts will pass through open air along side of the aluminum gear cross piece. See the picture in the link here (need to click on search by image): http://www.kisbuild.r-a-reed-assoc.com/KIS-TR1-Web/ScottSterns/landinggear1.JPG 2) "The bolts clamp the steel plate onto the flox pads and allow the bolts to be under a constant preload." Not quite correct. Here is the probable entire stack up sequence as I see it starting from the interior of the fuselage and working our way down. (Realize that not everything in this stack up is placed immediately on top of each other, but all parts or pieces are being ultimately clamped between the bolt head and nut): a) Bolt head. b) Probably a large area steel washer. c) Fuselage bottom shell (either fiberglass or carbon fiber). May be reinforced in the vicinity of the landing gear cross slot. d) Flox pad. e) Rubber pad. f) Aluminum landing gear cross piece. g) Steel plate (with four bolt holes). h) Probable steel washer. i) Nut (either self locking metal or nylon, or castellated with a cotter key). How close did I come? 3) "The rubber pad goes around the landing gear and not under the bolts." The rubber pad may not be directly under the bolts, but the pad definitely is in the stack up and is being ultimately clamped between the bolt head and nut. 4) "The bolts clamp the steel plate onto the flox pads and allow the bolts to be under a constant preload." It is interesting to speculate just how much relevant preload (stretch -- in the conventional sense of preloading a steel bolt) can be created on a steel bolt that has a rubber pad as part of the stack up between the bolt head and nut. 5) "The grove parts are a better option today though since they have a built in radius that allows the gear to flex so you don't need the rubber pad." I would take the position that any time you are clamping a hard metal object, steel or aluminum, against an epoxied fiberglass structure or flox pad that a flexible interface (rubber or elastomeric) pad is desirable in order to avoid crumbling any high spots or uneven areas. OC ================================================================ From: Scott Stearns Sent: Monday, December 15, 2014 4:04 PM Subject: Re: KIS-List: TR-1 Incident down under Hi Mike, The proper use of a bolt is to clamp parts directly together. Preloading a bolt is what we really do when we tighten a nut down to a certain torque value. The bolt stretches as you tighten the nut and the bolt provides a constant clamping force (preload) as long the load on the joint never exceeds the clamping force provided by preloaded bolt. A great example is the bolts that clamp the main rod bearings around the crankshaft of an engine. Lycoming is very specific on the procedure for torquing these bolts right down to specifying a specific thread lubrication fluid. You can imagine if half the nut torque is going into moving a burr through the threads and not into stretching the bolt then you will not get the correct bolt preload. In this case the joint will not be clamped together with a load greater than the load from moving the piston and the joint will open slightly and stretch the bolt with each load application. Now the load on the bolt is cycling instead of the bolt being under a constant preload keeping the joint clamped together. Eventually the bolt will fatigue and fail. As I recall this is what happened to the 400 hour since factory new engine in the original factory demo Cruiser leading to an off field landing. The landing gear bolts of course do not go through anywhere near the load cycles that the main bearing bolts do, but it is still good engineering to have bolted joints under a constant preload rather than cycling with every load cycle. This requires a continuous joint and not leaving any part of the bolt in the open air as in the factory landing gear installation. Here is a picture of my landing gear installation on my TR-1. The bolts clamp the steel plate onto the flox pads and allow the bolts to be under a constant preload. The grove parts are a better option today though since they have a built in radius that allows the gear to flex so you don't need the rubber pad. The rubber pad goes around the landing gear and not under the bolts. http://www.kisbuild.r-a-reed-assoc.com/KIS-TR1-Web/ScottSterns/landinggear1.JPG View on www.kisbuild.r-a-reed... Anyhow, this was probably more than you were asking for, but I hope it helps. Cheers, Scott From: Mike Pienaar <mjpienaar@shaw.ca> Sent: Sunday, December 14, 2014 5:54 PM Subject: Re: KIS-List: TR-1 Incident down under Thanks Scott, What do you mean by "they allow the bolts to be properly preloaded" Thanks for your help Mike ----- Original Message ----- From: Scott Stearns Sent: Sunday, December 14, 2014 4:21 PM Subject: Re: KIS-List: TR-1 Incident down under Yes, but grove does not make a 1.25" version so you would have to make a 0.25" spacer. Scott From: Mike Pienaar <mjpienaar@shaw.ca> Sent: Monday, December 8, 2014 4:49 PM Subject: Re: KIS-List: TR-1 Incident down under Hi Scott Would you recommend these gear installation blocks for the TR4 as well? Thanks Mike ----- Original Message ----- From: "Scott Stearns" <sstearns2@yahoo.com> Sent: Thursday, November 27, 2014 11:58 AM Subject: Re: KIS-List: TR-1 Incident down under > > I would recommend updating the gear installation using these gear blocks. > The blocks allow the gear to flex without affecting the bolts and they > allow the bolts to be properly preloaded. > > http://www.groveaircraft.com/radiusplates.html > > Scott > >> On Nov 26, 2014, at 6:38 AM, "mark_trickel" <marktrickel@gmail.com> >> wrote: >> >> >> KIS Incident Down Under >> >> With regret, I post this news from Australia - Michael Pattens TR-1 main >> gear collapsed during roll out after touchdown when one of the attach >> bolts let lose: >> >> Airframe event involving a Amateur Built Aircraft KIS TR-1, VH-AIG, >> Taree, Aerodrome, NSW on 9 September 1996. >> Following an uneventful flight, the pilot reported that the aircraft >> touched down normally. After rolling about 80 m the right wing dropped >> and the pilot suspected a tire had failed. But about 50 m further on he >> heard pronounced scraping noises and the aircraft slewed right then left >> before finally coming to a halt about 10 m to the left of the runway. A >> subsequent inspection of the aircraft revealed that the fixed landing >> gear attachment bolts had failed at the countersunk heads. The failure >> faces contained rust deposits, indicating the bolts had been cracked for >> some time prior to the accident. The manufacturer has subsequently >> changed the design specification to fit standard flat head bolts in place >> of countersunk bolts. >> >> The complete report is located here: >> http://www.atsb.gov.au/publications/investigation_reports/1996/aair/199602857.aspx >> >> I ran out to my hanger/shed, and checked mine (my TR-1C is a very early >> kit #23), it has the round Allen head bolts which are recessed into the >> attach bracket I will be checking them for any signs of corrosion or >> cracking, and I recommend you check yours too. Can anybody confirm that >> there was a change to a counter sunk flat head bolt??? Galin while you >> are down for repairs you may want to consider replacing these main gear >> bolts. >> >> Mark T. >> >> >> >> >> Read this topic online here: >> >> http://forums.matronics.com/viewtopic.php?p=434702#434702 >> >> >> >> >> >> >> >> >>-> hbsp; ======================== >>http://www.matronics.com/Navigator?KIS-List<; >>http://forums.==================== href="http://www.aeroelectric.com">www.aeroelectric.com href="http://www.buildersbooks.com">www.buildersbooks.com href="http://www.homebuilthelp.com">www.homebuilthelp.com href="http://www.mypilotstore.com">www.mypilotstore.com href="http://www.mrrace.com">www.mrrace.com href="http://www.matronics.com/contribution">http://www.matronics.com/chref="http://www.matronics.com/Navigator?KIS-List">http://www.matronics.com/Navigator?KIS-List href="http://forums.matronics.com">http://forums.matronics.com k" href="http://www.aeroelectric.com/">www.aeroelectric.com et="_blank" href="http://www.buildersbooks.com/">www.buildersbooks.com nk" href="http://www.homebuilthelp.com/">www.homebuilthelp.com ank" href="http://www.mypilotstore.com/">www.mypilotstore.com lank" href="http://www.mrrace.com/">www.mrrace.com "http://www.matronics.com/contribution">http://www.matronics.com/contribution "http://www.matronics.com/Navigator?KIS-List">http://www.matronics.com/Navigator?KIS-List "http://forums.matronics.com/">http://forums.matronics.com




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