X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-d20.mx.aol.com ([205.188.139.136] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2376663 for flyrotary@lancaironline.net; Tue, 09 Oct 2007 01:47:37 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.139.136; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-d20.mx.aol.com (mail_out_v38_r9.3.) id q.bcd.1601c5c1 (14502) for ; Tue, 9 Oct 2007 01:46:49 -0400 (EDT) From: Lehanover@aol.com Message-ID: Date: Tue, 9 Oct 2007 01:46:49 EDT Subject: Re: [FlyRotary] Re: Hose clamp myth busters To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1191908809" X-Mailer: 9.0 Security Edition for Windows sub 5378 X-Spam-Flag: NO -------------------------------1191908809 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 10/8/2007 2:09:41 P.M. Eastern Daylight Time, echristley@nc.rr.com writes: They lived for weeks with terrible injuries, and > both died leaving behind astounding medical bills and shattered families. > > Spring clamps are acceptable on vacuum hoses to power some back up gages. > I love the depth of information and experience you bring to this list, Lynn; but, unless you can point to a spring clamp being the cause of the mentioned accident, I'd say that it is completely irrelevant to this discussion. Mechanical failures happen, and often they could be delayed or avoided altogether if one part was just slightly stronger. But there's a long row to hoe to move from that statement to spring clamps only being acceptable for backup vacuum gauges. First of all, you probably won't get an airworthy sticker from your inspector if a cooling system hose has a spring clamp on it anywhere. You may have noticed that many of the boys are using full size upper hoses on their installations when a one inch, or one and a quarter inch hose is more than enough. The larger hose has significantly more area facing the coolant pressure than the smaller hose. My wife's Renault popped the head gasket and the wire formed hose clamps with a nut and bolt tensioner held up fine. The end tank of the radiator came uncrimped and blew off. But it wasn't a spring clamp. So there are situations where a spring clamp blowing off would have saved some money. But the Renault didn't have spring clamps. I am suggesting that the boys run a 22 or 24 pound cap instead of the more typical 12 or 16 pound cap. I am inviting others to believe me when I say this and this and that works. If somebody chooses to use the setup I suggest, then they leave off three of six major elements of that set up, what can I say? There is no positive locking feature on a spring clamp. You must trust that the heat treat was damn near perfect, on a piece that has less than 4 cents in its manufacture. There is no place for this device on any aircraft, even home built. It is not a reliability related decision. It is philosophical problem. Devices that do not display a positive locking feature are seldom seen on aircraft. We don't have solid data, so we fall back to what feels good, but there is some unintended hypocrisy going on here. If the spring clamps aren't up to the job, why would they be acceptable on back-up gauges? Those gauges are going to be the primary gauges after the primaries fail, and if the clamp failed it will kill ALL of them anyway. Why does it feel acceptable to use the clamps on the backups, but not the primaries? And why are the spring clamps found all over the cooling system of some of the most reliable passenger vehicles ever mass produced? I doubt Toyota, Honda, Ford, Dodge, or BMW use the feel good metric when specifying their clamps. Mostly wire frame clamps with bolt and nut plate, and not spring clamps, but mostly because they are cheap. There was no suggestion that spring clamps don't work, or are not reliable. I have never seen any AN drawings for a spring clamp. The spring clamp would work fine as a clamp for the back up vacuum gages, because the barbed fittings would work without the clamps anyway, and the suction on the lines will tend to keep them in place without the barbed fitting and without the clamp. The primary gages would be electric. I'm not really ranting about hose clamps as much as the feel good mentality . . . the dismissal of a solution without a quantification of what it's supposed to do. I'm using little velcro straps to contain my wire bundles. These things are amazing for a tube frame airplane. They're cheap, convenient, quick to install or move, allow some play in the wire while holding it securely and provide for non-abrasive separation from the structural tubes. "But it's just velcro," a friend complained. So I strapped a wire to a shelving support tube, and let him hang from it. He gave up when the wire was cutting into his hands instead of coming loose. The aviation industry is rife with over-engineering because someone needed an extra ten feet to make the runway. It's my belief that it does nothing but drive the price up. I say 'belief' because I have no actual data to back up the belief. Until there's some data showing how spring clamps will fail in a typical cooling system, I'm going to have to reject that notion. There's just way to much evidence showing that they do work...reliably...for years on end. There are many cases of under-design showing up each year, as once modern planes build up the hours. If you get a close look at the hinge joint on the 175 elevator, you probably would never fly one again. But they hold up just fine. On other designs not so well. Cracking bulkheads and skins and so-on. That being said, I'll actually use worm clamps. There's less worry about having the exact right size for every hose, simplifying my inventory management. The object of having extensive specifications for hose clamps and all of those dodads and nicknacks for aircraft, is not a result of lesser hose clamps having failed left and right at great loss of life and equipment. It is to reduce the possibility of failure from one in a million to one in a trillion, or an even lesser number. For any intent to below zero. There are many aircraft parts where this kind of thinking cannot be used, due to cost. But where it is possible, aircraft parts are failure proof, and must be defeated by bone headed mechanics and, or, fate, but not for lack of design or quality. Let the plane crash because of some pilot screwup, but please God not because we saved 76 cents on the hose clamps. 99.999 percent of the time, fasteners that are safety wired would not come undone should the wire be left off, done poorly or wired backwards so as to be pulling in the loosening direction. I have been working on airplanes since I was 14 years old. I am now 64. The house I just sold, has a Lear jet Fuselage in the game room. It isn't the one you did right that gets you. But if you forget just one of those guys. The one that has been in the trunion casting since 1949 will back out and hang up on the gear door and that gear will not extend. Maybe not today, maybe not this month, but it will. That nasty FAA man will show it to you. There are many things we could do and there would be no deadly outcome, this time. But then you end up with a big number of items that will not be accepted by the AI, so there is no monetary advantage. Stay on the side of the best pieces, the best practices, and read the stupid check list every time. Let somebody else test automobile fasteners in his airplane, or hose clamps, or whatever. If you need to sell it, it is better if it looks just like an F-16 inside. it's just my opinion.........I could be wrong. Lynn E. Hanover ************************************** See what's new at http://www.aol.com -------------------------------1191908809 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 10/8/2007 2:09:41 P.M. Eastern Daylight Time,=20 echristley@nc.rr.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>They=20 lived for weeks with terrible  injuries, and
> both died leavi= ng=20 behind astounding medical bills and shattered  families.
>&nbs= p;=20
> Spring clamps are acceptable on vacuum hoses to power some back=20 up  gages.
>  
I love the depth of information a= nd=20 experience you bring to this list,
Lynn;  but, unless you can poi= nt=20 to a spring clamp being the cause of
the mentioned accident, I'd say t= hat=20 it is completely irrelevant to this
discussion.  Mechanical failu= res=20 happen, and often they could be delayed
or avoided altogether if one p= art=20 was just slightly stronger.  But
there's a long row to hoe to mov= e=20 from that statement to spring clamps
only being acceptable for backup=20 vacuum gauges.
First of all, you probably won't get an airworthy sticker from=20= your=20 inspector if a cooling system hose has a spring clamp on it anywhere. You ma= y=20 have noticed that many of the boys are using full size upper hoses on their=20 installations when a one inch, or one and a quarter inch hose is more t= han=20 enough. The larger hose has significantly more area facing the coolant press= ure=20 than the smaller hose. My wife's Renault popped the head gasket and the wire= =20 formed hose clamps with a nut and bolt tensioner held up fine. The end=20= tank=20 of the radiator came uncrimped and blew off. But it wasn't a spring clamp. S= o=20 there are situations where a spring clamp blowing off would have saved some=20 money. But the Renault didn't have spring clamps. I am suggesting that the b= oys=20 run a 22 or 24 pound cap instead of the more typical 12 or 16 pound cap.=20
 
I am inviting others to believe me when I say this and this and= =20 that works. If somebody chooses to use the setup I suggest, then they leave=20= off=20 three of six major elements of that set up, what can I say?
 
There is no positive locking feature on a spring clamp. You mus= t=20 trust that the heat treat was damn near perfect, on a piece that has less th= an 4=20 cents in its manufacture. There is no place for this device on any aircraft,= =20 even home built. It is not a reliability related decision. It is philosophic= al=20 problem. Devices that do not display a positive locking feature are seldom s= een=20 on aircraft.
 
We don't have solid data, so we fall back to what feels good, but t= here=20
is some unintended hypocrisy going on here.  If the spring clamps=20 aren't
up to the job, why would they be acceptable on back-up gauges?&nb= sp;=20 Those
gauges are going to be the primary gauges after the primaries fail= ,=20 and
if the clamp failed it will kill ALL of them anyway.  Why does=20= it=20 feel
acceptable to use the clamps on the backups, but not the=20 primaries? 
 
 And why are the spring clamps found all over the cooling syst= em of=20 some of
the most reliable passenger vehicles ever mass produced?  I= =20 doubt
Toyota, Honda, Ford, Dodge, or BMW use the feel good metric when=20
specifying their clamps. Mostly wire frame clamps with bolt and=20= nut=20 plate, and not spring clamps,
but mostly because they are cheap.
 
There was no suggestion that spring clamps don't work, or are n= ot=20 reliable. I have never seen any AN drawings for a spring clamp. The spring c= lamp=20 would work fine as a clamp for the back up vacuum gages,
because the barbed fittings would work without the clamps anywa= y,=20 and the suction on the lines will tend
to keep them in place without the barbed fitting and=20 without the clamp. The primary gages would be electric.
 
I'm not really ranting about hose clamps as much as the feel good=20
mentality . . . the dismissal of a solution without a quantification of=20
what it's supposed to do.  I'm using little velcro straps to contai= n my=20
wire bundles.  These things are amazing for a tube frame=20 airplane. 
They're cheap, convenient, quick to install or move, all= ow=20 some play in
the wire while holding it securely and provide for non-abra= sive=20
separation from the structural tubes.  "But it's just velcro," a fr= iend=20
complained.  So I strapped a wire to a shelving support tube, and l= et=20
him hang from it.  He gave up when the wire was cutting into his ha= nds=20
instead of coming loose.

The aviation industry is rife with=20 over-engineering because someone
needed an extra ten feet to make the=20 runway.  It's my belief that it
does nothing but drive the price=20 up.  I say 'belief' because I have no
actual data to back up the=20 belief.  Until there's some data showing how
spring clamps will fai= l in=20 a typical cooling system, I'm going to have
to reject that notion. = =20 There's just way to much evidence showing that
they do work...reliably..= .for=20 years on end.
 
There are many cases of under-design showing up each year,=20= as=20 once modern planes build up the hours.
If you get a close look at the hinge joint on the 175 eleva= tor,=20 you probably would never fly one again. But they hold up just fine. On other= =20 designs not so well. Cracking bulkheads and skins and so-on.


That being said, I'll actually use worm clamps.  There's l= ess=20 worry
about having the exact right size for every hose, simplifying my=20
inventory management.
 
 
The object of having extensive specifications for hose clam= ps and=20 all of those dodads and nicknacks for aircraft, is not a result of lesser ho= se=20 clamps having failed left and right at great loss of life and equipment. It=20= is=20 to reduce the possibility of failure from one in a million to one in a trill= ion,=20 or an even lesser number. For any intent to below zero. There are many=20 aircraft parts where this kind of thinking cannot be used, due to cost. But=20 where it is possible, aircraft parts are failure proof, and must be defeated= by=20 bone headed mechanics and, or, fate, but not for lack of design or=20 quality. Let the plane crash because of some pilot screwup, but please=20= God=20 not because we saved 76 cents on the hose clamps. 99.999 percent of the time= ,=20 fasteners that are safety wired would not come undone should the wire be lef= t=20 off, done poorly or wired backwards so as to be pulling in the loosening=20 direction. I have been working on airplanes since I was 14 years old. I am n= ow=20 64. The house I just sold, has a Lear jet Fuselage in the game room. It isn'= t=20 the one you did right that gets you. But if you forget just one of those guy= s.=20 The one that has been in the trunion casting since 1949 will back out and ha= ng=20 up on the gear door and that gear will not extend.
 
Maybe not today, maybe not this month, but it will. That na= sty=20 FAA man will show it to you.
 
There are many things we could do and there would be no deadly=20 outcome, this time. But then you end up with a big number of items that will= not=20 be accepted by the AI, so there is no monetary advantage. Stay on the side o= f=20 the best pieces, the best practices, and read the stupid check list every ti= me.=20 Let somebody else test automobile fasteners in his airplane, or hose clamps,= or=20 whatever. If you need to sell it, it is better if it looks just like an F-16= =20 inside.  
it's just my opinion.........I could be wrong.
 
Lynn E. Hanover



See w= hat's new at AOL.c= om and Make AOL Your Homepage.
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