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
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| Subject: | 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-
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| Subject: | New builder--David McBride, upstate NY |
RGF2aWQhISENCg0KSXQgaXMgZ3JlYXQgdG8gc2VlIGEgeW91bmdlciBidWlsZGVyIG9uIHRoZSBs
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Message 3
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| Subject: | Space for construction |
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
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| Subject: | 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 5
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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
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| Subject: | Re: NEED ADVICE!!!! |
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 <douwe@douwestudios.com>
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
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| Subject: | Re: NEED ADVICE!!!! |
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Message 8
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| Subject: | Re: NEED ADVICE!!!! |
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
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| Subject: | 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
--> <thomas.e.stancy@boeing.com>
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
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| Subject: | 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 <jack@bedfordlandings.com>
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
--> <thomas.e.stancy@boeing.com>
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
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