---------------------------------------------------------- Pietenpol-List Digest Archive --- Total Messages Posted Wed 05/27/15: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:36 AM - Re: Re: new builder upstate NY (Jim Boyer) 2. 10:53 AM - New builder--David McBride, upstate NY (Cuy, Michael D. (GRC-LME0)[Vantage Partners, LLC]) 3. 11:06 AM - Space for construction (Pocono John) 4. 12:58 PM - Re: Caution - Rudder Bar Failure (tstancy) 5. 05:04 PM - NEED ADVICE!!!! (Douwe Blumberg) 6. 05:08 PM - Re: NEED ADVICE!!!! (Ken Bickers) 7. 05:14 PM - Re: NEED ADVICE!!!! (Boatright, Jeffrey) 8. 05:26 PM - Re: NEED ADVICE!!!! (curtdm(at)gmail.com) 9. 06:07 PM - Re: Re: Caution - Rudder Bar Failure (Jack Philips) 10. 07:19 PM - Re: Re: Caution - Rudder Bar Failure (goffelectric@comcast.net) ________________________________ Message 1 _____________________________________ Time: 10:36:39 AM PST US From: Jim Boyer Subject: Re: Pietenpol-List: Re: new builder upstate NY Hi David, Love your empirical testing setup. Nothing like practical tests to prove st rength. I am surprised that the hinges, screws/bolts, and pins (screwdriver ) actually held your weight at the length of lever arm. Cheers, Jim B. =C2- ________________________________ Message 2 _____________________________________ Time: 10:53:37 AM PST US From: "Cuy, Michael D. (GRC-LME0)[Vantage Partners, LLC]" Subject: Pietenpol-List: New builder--David McBride, upstate NY RGF2aWQhISENCg0KSXQgaXMgZ3JlYXQgdG8gc2VlIGEgeW91bmdlciBidWlsZGVyIG9uIHRoZSBs aXN0IGFuZCBvbiBGQi4gICAgWW91IGNhbiB0ZWxsIGFpcnBsYW5lcyBhcmUgaW4geW91ciBibG9v ZCBhbmQgYnVpbGRpbmcgaXMgZ29pbmcgdG8ga2VlcCBnb2luZyBmb3J3YXJkIGZvciB5b3UNCmFu ZCBzb21lZGF5IHlvdSB3aWxsIGhhdmUgYSBmbHlpbmcgUGlldGVucG9sIEFpciBDYW1wZXIhDQoN CkdyZWF0IHRvIHNlZSB5b3VyIHBob3RvcyBvZiB0aGUgR3JlYXRlciBSb2NoZXN0ZXIgQWlyIFNo b3cgdG9vLiAgIFlvdSB3ZXJlIGEgYnVzeSBndXkgd29ya2luZyB0aGF0IGFsbCB3ZWVrZW5kIEni gJlsbCBiZXQuDQoNCkkgcmVtZW1iZXIgdGhlIFBpZXRlbnBvbCBtb3ZlbWVudCBiZWluZyBhIGJ1 bmNoIG9mIGdydW1weSBvbGRlciBndXlzIHdoZW4gSSBnb3QgaW50byBpdCBpbiB0aGUgbGF0ZSAx OTgw4oCZcyBidXQgYW5kIG5vdyBJIEFNIG9uZSBvZiB0aG9zZSBncnVtcHkNCm9sZCBndXlzIHNv IGl0IHN1cmUgaXMgcmVmcmVzaGluZyB0byBzZWUgc29tZSB5b3VuZ2VyIGd1eXMgZ2V0dGluZyBp bnRvIGJ1aWxkaW5nIHRoaXMgb2xkIGFpcnBsYW5lLg0KDQpLZWVwIHVzIHBvc3RlZCENCg0KTWlr ZSBDdXkNCk9oaW8NCg0KDQo ________________________________ Message 3 _____________________________________ Time: 11:06:22 AM PST US Subject: Pietenpol-List: Space for construction From: "Pocono John" I packed up the project a few months ago in preparation to sell our house. We'll probably buy land and build a new house. We found one set of plans that we like. Next to the two car garage is a enclosed workshop/third garage. It measures 23'10" X 11' 10". With every foot I extend this, I'm paying more for the slab (since it's part of the garage section) and roof and walls (and heating). In a way, kind of dream to be able to design my play area. I may add two feet or so to make it 14' wide.I can always move my car out for smaller jobs as the tools are on rolling tables. What's your idea of the perfect construction area? Is there something you wish you had? Where are you building now (or where did you build)? What if you could design a room? -------- John Read this topic online here: http://forums.matronics.com/viewtopic.php?p=442612#442612 ________________________________ Message 4 _____________________________________ Time: 12:58:25 PM PST US Subject: Pietenpol-List: Re: Caution - Rudder Bar Failure From: "tstancy" In the spirit of gaining a greater understanding of why this type of failure occurred, I would like to present the following proposal: >From the Aircraft Spruce website for AN5 Bolts (5/16-24), on the Overview Tab it states, Hex head aircraft bolts are made of high-strength type 4037 or 8740 alloy steel (type 8740 is the most commonly used). Ref: http://www.aircraftspruce.com/catalog/hapages/an5.php >From the TW Metals website for 8740 Alloy Bar, the Minimum Tensile Yield Strength is 152,000 psi. Ref: http://www.twmetals.com/8740-bar-rod-wire.html However, when an AN5 fastener is heated to 1500 degrees F (such as during the welding process), the fastener becomes Annealed in the Heat Affected Zone and then only possesses a Tensile Yield Strength of 60,200 psi. Ref: http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=M874AB Multiplying the annealed Tensile Yield Strength value of 60,200 psi by the AN5 bolts cross-section area (.07499 square inches at the bolts minimum design diameter of .309), we find the Annealed AN5 Bolt can handle 4,514 pounds of Tensile Force before it begins to yield (permanently deform). Example: 60,200 (pounds/square inch) x .07499 (square inches) = 4,514 (pounds) Assumption: A human cannot apply 4,500 pounds of load to the Rudder Pivot Point, even with both feet and a lever arm of approximately 1 inch. Therefore, the following Static Strength Conclusion can be made: An Annealed AN5 Bolt is more than strong enough to handle the Rudder Bar Pedal loads. So, what happened? A Stainless Steel Bolt when heated to a high temperature (i.e. welding) will absorb Hydrogen molecules, if Hydrogen is present in the atmosphere during the elevated temperature period. These Hydrogen molecules combine with the Carbon that is alloyed to the Iron to form Methane Gas. The Methane Gas collects in small voids along the grain boundaries where it builds up enormous pressures that will eventually initiate cracks. These cracks will initiate quicker and propagate under load. This is called Hydrogen Embrittlement cracking. Ref: http://www.corrosionist.com/hydrogen_embrittlement_stainless_steels.htm These micro-cracks would propagate during the cycling action of applying the Rudder. Therefore, Hydrogen Embrittlement fatigue cracking is the most likely cause of this Rudder Bar Bolt failure. To avoid absorbing Hydrogen molecules, you must remove all exposure to Hydrogen during the welding process and continue to maintain a Hydrogen-free atmosphere during the cooling process (i.e. continual inert gas flow). An alternative to Welding is Brazing (per the plan). Brazing occurs around 800 degrees F and provides sufficient mechanical strength necessary to create a Rudder Bar Pivot Point, even though the AN5 Bolt is annealed during the Brazing process. At this reduced temperature, Hydrogen molecules are not absorbed into the grain boundary of the Stainless Steel. Respectfully, Tom Stancy Read this topic online here: http://forums.matronics.com/viewtopic.php?p=442625#442625 ________________________________ Message 5 _____________________________________ Time: 05:04:00 PM PST US From: "Douwe Blumberg" Subject: Pietenpol-List: NEED ADVICE!!!! Hey guys, I just found out about a potential disaster.. Turns out I have to do a presentation in Denver the Friday morning of Brodhead. THIS CANT BE REAL!!!!!!! So, I'm trying to figure out where is the closest to Brodhead I could catch a flight Thursday night or super early Friday for Denver, do the presentation Friday morning and fly back so I could be there for Sat morning dawn patrol. Marci will be there with our car to drive me and pick me up. Do any of you commercial dudes know which airports are around there? Is Madison decently large?? Douwe ________________________________ Message 6 _____________________________________ Time: 05:08:49 PM PST US Subject: Re: Pietenpol-List: NEED ADVICE!!!! From: Ken Bickers Douwe, there are some direct non-stop flights between Madison and Denver but not many. If not Madison, your best bet is probably O'Hare. There are scads of flights between there and Denver each day. Cheers, Ken On Wed, May 27, 2015 at 6:04 PM, Douwe Blumberg wrote: > Hey guys, > > > I just found out about a potential disaster. > > > Turns out I have to do a presentation in Denver the Friday morning of > Brodhead. THIS CANT BE REAL!!!!!!! > > > So, I=99m trying to figure out where is the closest to Brodhead I c ould > catch a flight Thursday night or super early Friday for Denver, do the > presentation Friday morning and fly back so I could be there for Sat > morning dawn patrol. Marci will be there with our car to drive me and pi ck > me up. > > > Do any of you commercial dudes know which airports are around there? Is > Madison decently large?? > > > Douwe > > * > =========== .matronics.com/Navigator?Pietenpol-List> =========== =========== om/contribution> =========== > > * > > ________________________________ Message 7 _____________________________________ Time: 05:14:36 PM PST US From: "Boatright, Jeffrey" Subject: Re: Pietenpol-List: NEED ADVICE!!!! 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From: "curtdm(at)gmail.com" Douwe, Southwest has non-stops from MKE to DEN Thursday 7:40pm lands 9:10 Friday 5:35am lands 7:05 Return Friday 4:00pm lands 7:10 Friday 8:45pm lands 11:55 -------- Curt Merdan Flower Mound, TX Read this topic online here: http://forums.matronics.com/viewtopic.php?p=442639#442639 ________________________________ Message 9 _____________________________________ Time: 06:07:24 PM PST US From: "Jack Philips" Subject: RE: Pietenpol-List: Re: Caution - Rudder Bar Failure Tom, I definitely think the bolt developed a crack from the welding process. I don't know if hydrogen embrittlement was the culprit (it's not stainless steel, but other forms of steel can be susceptible to hydrogen embrittlement as well). Your analysis is correct, and an annealed bolt should be more than strong enough, which is why I felt welding it was safe. I think the tension applied to the rudder bar by the tailwheel steering springs, counteracted by forces from the pilot's (my) feet, set up a slight oscillating displacement which allowed the crack to propagate to the point of ultimate failure. Brazing would be best, but I had read several articles that claim you should not braze 4130 chromoly steel. Since 4130 is what I had, and I didn't have any brazing rod, I decided to weld it. I'm not alone, nearly every Pietenpol builder I've talked to about this also welded theirs. The unsettling thing about this failure is the inherent lack of inspectability. I do think adding a second diagonal brace going to the left side will vastly improve the strength of the whole assembly. It has always bothered me how much up and down play there can be at the ends of a Pietenpol rudder bar. Some of that is due to the fact that the assembly is not well constrained. So I agree with your conclusion, and recommend that all builders who are in the process should "build it to the plans" (have we heard that somewhere before?). Braze, rather than weld that bolt. And while you are at it, add the left hand diagonal brace, such as WACO airplanes did on their rudder bars. Jack Phillips NX899JP Smith Mountain Lake, Virginia -----Original Message----- From: owner-pietenpol-list-server@matronics.com [mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of tstancy Sent: Wednesday, May 27, 2015 3:58 PM Subject: Pietenpol-List: Re: Caution - Rudder Bar Failure --> In the spirit of gaining a greater understanding of why this type of failure occurred, I would like to present the following proposal: >From the Aircraft Spruce website for AN5 Bolts (5/16-24), on the >Overview Tab it states, Hex head aircraft bolts are made of >high-strength type 4037 or 8740 alloy steel (type 8740 is the most >commonly used). Ref: http://www.aircraftspruce.com/catalog/hapages/an5.php >From the TW Metals website for 8740 Alloy Bar, the Minimum Tensile Yield Strength is 152,000 psi. Ref: http://www.twmetals.com/8740-bar-rod-wire.html However, when an AN5 fastener is heated to 1500 degrees F (such as during the welding process), the fastener becomes Annealed in the Heat Affected Zone and then only possesses a Tensile Yield Strength of 60,200 psi. Ref: http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=M874AB Multiplying the annealed Tensile Yield Strength value of 60,200 psi by the AN5 bolts cross-section area (.07499 square inches at the bolts minimum design diameter of .309), we find the Annealed AN5 Bolt can handle 4,514 pounds of Tensile Force before it begins to yield (permanently deform). Example: 60,200 (pounds/square inch) x .07499 (square inches) = 4,514 (pounds) Assumption: A human cannot apply 4,500 pounds of load to the Rudder Pivot Point, even with both feet and a lever arm of approximately 1 inch. Therefore, the following Static Strength Conclusion can be made: An Annealed AN5 Bolt is more than strong enough to handle the Rudder Bar Pedal loads. So, what happened? A Stainless Steel Bolt when heated to a high temperature (i.e. welding) will absorb Hydrogen molecules, if Hydrogen is present in the atmosphere during the elevated temperature period. These Hydrogen molecules combine with the Carbon that is alloyed to the Iron to form Methane Gas. The Methane Gas collects in small voids along the grain boundaries where it builds up enormous pressures that will eventually initiate cracks. These cracks will initiate quicker and propagate under load. This is called Hydrogen Embrittlement cracking. Ref: http://www.corrosionist.com/hydrogen_embrittlement_stainless_steels.htm These micro-cracks would propagate during the cycling action of applying the Rudder. Therefore, Hydrogen Embrittlement fatigue cracking is the most likely cause of this Rudder Bar Bolt failure. To avoid absorbing Hydrogen molecules, you must remove all exposure to Hydrogen during the welding process and continue to maintain a Hydrogen-free atmosphere during the cooling process (i.e. continual inert gas flow). An alternative to Welding is Brazing (per the plan). Brazing occurs around 800 degrees F and provides sufficient mechanical strength necessary to create a Rudder Bar Pivot Point, even though the AN5 Bolt is annealed during the Brazing process. At this reduced temperature, Hydrogen molecules are not absorbed into the grain boundary of the Stainless Steel. Respectfully, Tom Stancy Read this topic online here: http://forums.matronics.com/viewtopic.php?p=442625#442625 ________________________________ Message 10 ____________________________________ Time: 07:19:32 PM PST US From: goffelectric@comcast.net Subject: RE: Pietenpol-List: Re: Caution - Rudder Bar Failure I am at this point in my build. I don't know anything about brazing. Could it just be tacked well on two sides of the head instead of welded all the way around the head? Thanks, Keith Goff ----- Original Message ----- From: Jack Philips Sent: Thu, 28 May 2015 01:06:56 -0000 (UTC) Subject: RE: Pietenpol-List: Re: Caution - Rudder Bar Failure Tom, I definitely think the bolt developed a crack from the welding process. I don't know if hydrogen embrittlement was the culprit (it's not stainless steel, but other forms of steel can be susceptible to hydrogen embrittlement as well). Your analysis is correct, and an annealed bolt should be more than strong enough, which is why I felt welding it was safe. I think the tension applied to the rudder bar by the tailwheel steering springs, counteracted by forces from the pilot's (my) feet, set up a slight oscillating displacement which allowed the crack to propagate to the point of ultimate failure. Brazing would be best, but I had read several articles that claim you should not braze 4130 chromoly steel. Since 4130 is what I had, and I didn't have any brazing rod, I decided to weld it. I'm not alone, nearly every Pietenpol builder I've talked to about this also welded theirs. The unsettling thing about this failure is the inherent lack of inspectability. I do think adding a second diagonal brace going to the left side will vastly improve the strength of the whole assembly. It has always bothered me how much up and down play there can be at the ends of a Pietenpol rudder bar. Some of that is due to the fact that the assembly is not well constrained. So I agree with your conclusion, and recommend that all builders who are in the process should "build it to the plans" (have we heard that somewhere before?). Braze, rather than weld that bolt. And while you are at it, add the left hand diagonal brace, such as WACO airplanes did on their rudder bars. Jack Phillips NX899JP Smith Mountain Lake, Virginia -----Original Message----- From: owner-pietenpol-list-server@matronics.com [mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of tstancy Sent: Wednesday, May 27, 2015 3:58 PM Subject: Pietenpol-List: Re: Caution - Rudder Bar Failure --> In the spirit of gaining a greater understanding of why this type of failure occurred, I would like to present the following proposal: >From the Aircraft Spruce website for AN5 Bolts (5/16-24), on the >Overview Tab it states, Hex head aircraft bolts are made of >high-strength type 4037 or 8740 alloy steel (type 8740 is the most >commonly used). Ref: http://www.aircraftspruce.com/catalog/hapages/an5.php >From the TW Metals website for 8740 Alloy Bar, the Minimum Tensile Yield Strength is 152,000 psi. Ref: http://www.twmetals.com/8740-bar-rod-wire.html However, when an AN5 fastener is heated to 1500 degrees F (such as during the welding process), the fastener becomes Annealed in the Heat Affected Zone and then only possesses a Tensile Yield Strength of 60,200 psi. Ref: http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=M874AB Multiplying the annealed Tensile Yield Strength value of 60,200 psi by the AN5 bolts cross-section area (.07499 square inches at the bolts minimum design diameter of .309), we find the Annealed AN5 Bolt can handle 4,514 pounds of Tensile Force before it begins to yield (permanently deform). Example: 60,200 (pounds/square inch) x .07499 (square inches) = 4,514 (pounds) Assumption: A human cannot apply 4,500 pounds of load to the Rudder Pivot Point, even with both feet and a lever arm of approximately 1 inch. Therefore, the following Static Strength Conclusion can be made: An Annealed AN5 Bolt is more than strong enough to handle the Rudder Bar Pedal loads. So, what happened? A Stainless Steel Bolt when heated to a high temperature (i.e. welding) will absorb Hydrogen molecules, if Hydrogen is present in the atmosphere during the elevated temperature period. These Hydrogen molecules combine with the Carbon that is alloyed to the Iron to form Methane Gas. The Methane Gas collects in small voids along the grain boundaries where it builds up enormous pressures that will eventually initiate cracks. These cracks will initiate quicker and propagate under load. This is called Hydrogen Embrittlement cracking. Ref: http://www.corrosionist.com/hydrogen_embrittlement_stainless_steels.htm These micro-cracks would propagate during the cycling action of applying the Rudder. Therefore, Hydrogen Embrittlement fatigue cracking is the most likely cause of this Rudder Bar Bolt failure. To avoid absorbing Hydrogen molecules, you must remove all exposure to Hydrogen during the welding process and continue to maintain a Hydrogen-free atmosphere during the cooling process (i.e. continual inert gas flow). An alternative to Welding is Brazing (per the plan). Brazing occurs around 800 degrees F and provides sufficient mechanical strength necessary to create a Rudder Bar Pivot Point, even though the AN5 Bolt is annealed during the Brazing process. At this reduced temperature, Hydrogen molecules are not absorbed into the grain boundary of the Stainless Steel. Respectfully, Tom Stancy Read this topic online here: http://forums.matronics.com/viewtopic.php?p=442625#442625 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message pietenpol-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Pietenpol-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/pietenpol-list Browse Digests http://www.matronics.com/digest/pietenpol-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.