X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 17 Oct 2008 07:41:44 -0400 Message-ID: X-Original-Return-Path: Received: from smtp107.sbc.mail.mud.yahoo.com ([68.142.198.206] verified) by logan.com (CommuniGate Pro SMTP 5.2.8) with SMTP id 3216688 for lml@lancaironline.net; Fri, 17 Oct 2008 04:19:54 -0400 Received: (qmail 25631 invoked from network); 17 Oct 2008 08:19:54 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=swbell.net; h=Received:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MIMEOLE; b=zjhiCAFYGMVNsBb8gW3icQ46bKxfGiMsfnSr774LSTPsOX2qkFUvOm3MiDSGPbtrawu9rEiq5T2JlhE8hLLlHqMo95IFgzHbf5+jJ8h+CjR6zDEDE7VPKAsQtdiJBZJIk7vtoop60ETRM00dqqtrjwoXwWrrpgTcvki8Jeh7AxM= ; Received: from unknown (HELO eaglenest61) (gbfitz@99.144.119.253 with login) by smtp107.sbc.mail.mud.yahoo.com with SMTP; 17 Oct 2008 08:19:53 -0000 X-YMail-OSG: FGYy6YAVM1kBZEsDQgV67kuUqd48hTrvzpqwJLJioMI4AiYEUIL5oCJxuBD6aEHB6gbB8lzYfp1N.jwBxnUj54Vx2yfukKWWnvJNDXnzhhEz1vfkYKCJvy.dMzQR3dQEIQv8B79LC_xcbgM6gx75k0rT X-Yahoo-Newman-Property: ymail-3 X-Original-Message-ID: <00a601c93030$5ec5e200$4001a8c0@eaglenest61> From: "Gary Fitzgerald" X-Original-To: "Lancair Mailing List" References: Subject: [LML] Re: Seat Belts X-Original-Date: Fri, 17 Oct 2008 03:14:25 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00A3_01C93006.7539F780" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1807 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1896 This is a multi-part message in MIME format. ------=_NextPart_000_00A3_01C93006.7539F780 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Kevin, I interpreted the guidance the same way you did. The installation = instructions for several makes of auto racing harnesses seem to agree, = also. One manufacturer specifies that the shoulder harness can be = anchored up to -40 degrees from the shoulder tangent, but not more than = 4" below the shoulder line, however every other manufacturer, and the = SFI Foundation itself (the people who certify safety equipment for = racing cars), recommend -10 degrees or less. An interesting side point is that the SFI Foundation no longer certifies = Y-type harnesses for it's competition classes. I wish I still had the = article explaining this, but I seem to remember it had something to do = with a pendulum effect, where the length of the harness between the = shoulder and the mounting point will allow the torso to move from side = to side in case of an accident. Ron's installation doesn't seem to have = this problem. I've tried to figure out some way of attaching a harness mounting point = or a harness bar directly behind the seats, but everything I could come = up with either interferes with the canopy latching mechanism or cuts off = access to the baggage area, or both. Gary Fitzgerald LNC2 extra-slow build ~70% engine: TBD St. Charles, MO ----- Original Message -----=20 From: Kevin Stallard=20 To: lml@lancaironline.net=20 Sent: Sunday, September 14, 2008 9:55 PM Subject: [LML] Seat Belts I was looking on Don Barne's site (thanks Don, as many have said, your = site is really nice) on the subject of seat belts. Specifically =20 http://www.lancairlegacy.com/tips_harness.html =20 I downloaded and was browsing through the FAA Advisory Circular (AC) = 21-34 concerning seatbelt harnesses, and it seemed to contradict Ron = Brice's note about seatbelts mounted overhead.=20 =20 = http://rgl.faa.gov/Regulatory_and_Guidance_Library\rgAdvisoryCircular.nsf= /0/5214C6FFB14E1383862569B2005E77F9?OpenDocument =20 (page 26) =20 It says that "Low attachments create spinal compression" and high = attachments cause additional structural loads and poor restraint, not = the other way around as Rice's note suggests.=20 =20 It seems the system Rice put in, unless greater than -8 degrees = tangent with the top of your shoulder would be the dangerous one to your = spine, not the overhead (over +30 degrees tangent). =20 Did I miss something? It seems that the drawback to the overhead = isn't problems with spine crushing; it's insuring the structure is = strong enough to keep the belts in place? Is this correct? =20 Thanks Kevin =20 =20 ------=_NextPart_000_00A3_01C93006.7539F780 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Kevin,
 
I interpreted the guidance the same way = you=20 did.  The installation instructions for several makes = of auto=20 racing harnesses seem to agree, also. One manufacturer specifies = that the=20 shoulder harness can be anchored up to -40 degrees from the shoulder = tangent,=20 but not more than 4" below the shoulder line, however every other = manufacturer,=20 and the SFI Foundation itself (the people who certify safety equipment = for=20 racing cars), recommend -10 degrees or less.
 
An interesting side point is that the = SFI=20 Foundation no longer certifies Y-type harnesses for it's competition=20 classes.  I wish I still had the article explaining this, but I = seem to=20 remember it had something to do with a pendulum effect, where the length = of the=20 harness between the shoulder and the mounting point will allow the torso = to move=20 from side to side in case of an accident.  Ron's installation = doesn't seem=20 to have this problem.
 
I've tried to figure out some way of = attaching a=20 harness mounting point or a harness bar directly behind the seats, but=20 everything I could come up with either interferes with the canopy = latching=20 mechanism or cuts off access to the baggage area, or both.
 
Gary Fitzgerald
LNC2 extra-slow = build=20 ~70%
engine: TBD
St. Charles, MO
----- Original Message -----
From:=20 Kevin = Stallard=20
Sent: Sunday, September 14, = 2008 9:55=20 PM
Subject: [LML] Seat Belts

I was looking on Don = Barne=92s site=20 (thanks Don, as many have said, your site is really nice) on the = subject of=20 seat belts.  Specifically

 

http://www.lancai= rlegacy.com/tips_harness.html

 

I downloaded and was = browsing=20 through the FAA Advisory Circular (AC) 21-34 concerning seatbelt = harnesses,=20 and it seemed to contradict Ron Brice=92s note about seatbelts mounted = overhead.=20

 

http://rgl.faa.= gov/Regulatory_and_Guidance_Library\rgAdvisoryCircular.nsf/0/5214C6FFB14E= 1383862569B2005E77F9?OpenDocument

 

(page 26)

 

It says that =93Low attachments create = spinal=20 compression=94 and high attachments cause additional structural loads = and poor=20 restraint, not the other way around as Rice=92s note suggests.=20

 

It seems the system Rice put in, unless = greater than=20 -8 degrees tangent with the top of your shoulder would be the = dangerous one to=20 your spine, not the overhead (over +30 degrees=20 tangent).

 

Did I miss = something?  It=20 seems that the drawback to the overhead isn=92t problems with spine = crushing;=20 it=92s insuring the structure is strong enough to keep the belts in = place? =20 Is this correct?

 

Thanks

Kevin

 

 

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