Venturi
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
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- Posts: 23
- Joined: Mon Sep 23, 2002 7:26 pm
Venturi
Hi,
I have a 52 170B with one 4" venturi (10" long) with adjustable regulator running an old AN DG. I added an RC Allen AI. I still will get 4.75-5.25in Vacuum in cruse with both units hooked up. I am going to replace the old AN DG with RC Allen DG. I have seen a lot of 170s with two venturi I don not want to add a second venturi. Has anyone used an 9" (11.25" long) #15052 venturi to run two modern gyros?
Thanks
Collin
I have a 52 170B with one 4" venturi (10" long) with adjustable regulator running an old AN DG. I added an RC Allen AI. I still will get 4.75-5.25in Vacuum in cruse with both units hooked up. I am going to replace the old AN DG with RC Allen DG. I have seen a lot of 170s with two venturi I don not want to add a second venturi. Has anyone used an 9" (11.25" long) #15052 venturi to run two modern gyros?
Thanks
Collin
'52 170 N2768D
Collin Gyenes
Oregon Rep
Collin Gyenes
Oregon Rep
The Instrument Flight equipped 170B had two venturi's interconnected, just as depicted in the IPC. Those wanting to change the system, might wish to consider their basis of approval, not only for an unapproved change in design, but also for certification approval (PMA) for the venturi's. The original venturi's were AN5807 specification. What are "super" venturi basis of approval? And where is their parts manufacturing authority? And by what approval are they installed if they are not approved parts? Just some thoughts.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
The venturis supplied by Wag-Aero meet the definition of "Standard Parts" in AC20-62D. They have 2", 4" and 8" venturis available that meet AN standards. The 9" supplied by Spruce does not. I got one of these from a friend hoping it would be usable but decided against it. Now the question is, would it be legal to use any other configuration other than the one shown in IPC, i.e. two 8" venturis in parallel, or one 8"?
Karl
'53 170B N3158B SN:25400
ASW-20BL
'53 170B N3158B SN:25400
ASW-20BL
- Bruce Fenstermacher
- Posts: 10318
- Joined: Tue Apr 23, 2002 11:24 am
It's a venturi for !@$%&@ sake. No moving parts. It's well made, can't really tell its any different than the original except a little longer. My IA recommended this procedure and has installed many of these exact 9" venturis on 170's for the reason to keep things simple and clean with only one venturi. I examined my original 4" venturi and didn't see any FAA PMA sticker or part number either. I think this one is really a minor technicality. It's not like we installed a Holly 4 barrel carb on the engine or something.
My two cents, Bruce
My two cents, Bruce
- Joe Moilanen
- Posts: 598
- Joined: Sun Dec 28, 2003 5:45 am
AC20-62D "Standard Part. Is a part manufactured in complete compliance with an established U.S. GovernmentN9149A wrote:Karl how do you know the Wag-Aero venturis meet AC20-62D? What part of it do they meet?
or industry-accepted specification which includes design, manufacturing, and uniform identification requirements.
The specification must include all information necessary to produce and conform the part. The specification
must be published so that any party may manufacture the part. Examples include, but are not limited
to, National Aerospace Standards (NAS), Air Force-Navy Aeronautical Standard (AN), Society of Automotive
Engineers (SAE), SAE Aerospace Standard (AS), Military Standard (MS), etc."
Wag-Aero list their venturis as "Code 5". If you go to the back of their catalog it list Code 5 it says "These items meet AN, MS, NAS or other Military specifications or may be identified as Standard Parts as defined by the FAA."
Karl
'53 170B N3158B SN:25400
ASW-20BL
'53 170B N3158B SN:25400
ASW-20BL
I hear ya Bruce, your preaching to the choir here. I would love to strap that big puppy on there, but our Feds out here in CA are not so forgiving, and neither is my IA.N3243A wrote:It's a venturi for !@$%&@ sake. No moving parts. It's well made, can't really tell its any different than the original except a little longer.
Your right - it is a pretty simple device (that is the beauty of it in my mind). It seems that Spruce could get the super venturi approved under a "AN" classification easily enough.
Karl
'53 170B N3158B SN:25400
ASW-20BL
'53 170B N3158B SN:25400
ASW-20BL
Ha! I know what you mean, Bruce. It's irritating when life really should be simpler.N3243A wrote:It's a venturi for !@$%&@ sake. No moving parts. It's well made, can't really tell its any different than the original except a little longer. My IA recommended this procedure and has installed many of these exact 9" venturis on 170's for the reason to keep things simple and clean with only one venturi. I examined my original 4" venturi and didn't see any FAA PMA sticker or part number either. I think this one is really a minor technicality. It's not like we installed a Holly 4 barrel carb on the engine or something.
My two cents, Bruce
But to address your observation, just for discussion's sake ...
".. can't really tell its any different than the original except a little longer..." it's different size is the proof that it doesn't conform to the original "approved" design. If I was an inspector it'd stand out like a sore thumb.
"...didn't see any FAA PMA sticker or part number ..." -The part number is listed in the IPC as AN5807-1,...a standard, approved specification. Any other requires additional approval.
"It's a venturi for !@$%&@ sake..." Ha! Yes, but there are those who would argue that's why it's important that it be approved! It's the sole-source power for critical instruments.
"It's not like we installed a Holly 4 barrel carb ..." A single barrel carburetor is a pretty simple thing too! Except that the two-piece venturi in it can cause loss of engine power, so an AD note was issued.
Is the "super" venturi's throat machine-fit/swaged or is it one-piece cast and machine-finished like the AN5807 spec.? Vibration might make that an important distinction up there in the clouds. Those are the sort of questions answered by such things as AN specifications.
BTW, I have a copy of the AN5807 specs posted at the old site if anyone was curious about them. Bruce is right, it's dirt-simple. I love it. Hate dry-pumps.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
George,
Well I would bet $100 that the average FAA FSDO inspector could not tell the difference at glance between a 4" and a 9" venturi. You have lots of type specific experience that allows you to tell the difference but does not reflect the experience of most ASI's.
I agree that there is a Part Number listed for the 4" venturi in the IPC bit I don't see the PN stamped on my old venturi, so how do I know Cessna or someone else put the proper AN5807-1 on in the first place? My point is that that these aren't all that well documented anyway.
If you use your airplane IFR maybe you have a point about powering your critical gyro instruments with the "approved setup". I use mine for VFR only so if the venturi fell off because Spruce made it from paper mache' it would be no big deal to me. But I'm just not to worried about the quality of the part. The throat looked nicely machined to me. This is probably not the time to mention that I also have a Spruce ACS products mixture control either (also installed and documented by my mech.)
On a related issue, the famous F. Atlee Dodge here in Anchorage sells generic Bowden cables (solid wire in wound casing) for carb heat, cabin heat, cabin air, etc. complete with nicely labled knobs. No where do the cables have an FAA PMA sticker yet they are found in many Supercubs and Cessnas across Alaska. No one seems to get too upset about this type of minor stuff up here (A&P's or FAA). In fact much of Atlee's stuff doesn't have PMA stickers yet his name and products are so well regarded that it appears to be overlooked by the FSDO in my opinion. Another reason why Alaska is a great place to live and fly!!
Bruce
Well I would bet $100 that the average FAA FSDO inspector could not tell the difference at glance between a 4" and a 9" venturi. You have lots of type specific experience that allows you to tell the difference but does not reflect the experience of most ASI's.
I agree that there is a Part Number listed for the 4" venturi in the IPC bit I don't see the PN stamped on my old venturi, so how do I know Cessna or someone else put the proper AN5807-1 on in the first place? My point is that that these aren't all that well documented anyway.
If you use your airplane IFR maybe you have a point about powering your critical gyro instruments with the "approved setup". I use mine for VFR only so if the venturi fell off because Spruce made it from paper mache' it would be no big deal to me. But I'm just not to worried about the quality of the part. The throat looked nicely machined to me. This is probably not the time to mention that I also have a Spruce ACS products mixture control either (also installed and documented by my mech.)
On a related issue, the famous F. Atlee Dodge here in Anchorage sells generic Bowden cables (solid wire in wound casing) for carb heat, cabin heat, cabin air, etc. complete with nicely labled knobs. No where do the cables have an FAA PMA sticker yet they are found in many Supercubs and Cessnas across Alaska. No one seems to get too upset about this type of minor stuff up here (A&P's or FAA). In fact much of Atlee's stuff doesn't have PMA stickers yet his name and products are so well regarded that it appears to be overlooked by the FSDO in my opinion. Another reason why Alaska is a great place to live and fly!!
Bruce
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