X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 12 Mar 2014 18:22:23 -0400 Message-ID: X-Original-Return-Path: Received: from blu0-omc3-s33.blu0.hotmail.com ([65.55.116.108] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTP id 6771873 for lml@lancaironline.net; Wed, 12 Mar 2014 16:46:53 -0400 Received-SPF: pass receiver=logan.com; client-ip=65.55.116.108; envelope-from=gary21sn@hotmail.com Received: from BLU172-DS9 ([65.55.116.74]) by blu0-omc3-s33.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675); Wed, 12 Mar 2014 13:46:17 -0700 X-TMN: [fwrrQyaI1AuVus5fIxudoCcuSS09k+sR] X-Originating-Email: [gary21sn@hotmail.com] X-Original-Message-ID: X-Original-Return-Path: gary21sn@hotmail.com From: "Gary Edwards" X-Original-To: "Lancair Mailing List" References: Subject: Re: Exhaust pipe failure X-Original-Date: Wed, 12 Mar 2014 13:46:21 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_010A_01CF3DF9.73C90A60" In-Reply-To: X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 Seal-Send-Time: Wed, 12 Mar 2014 13:46:21 -0700 X-MimeOLE: Produced By MSN MimeOLE V10.50.0019.1000 X-OriginalArrivalTime: 12 Mar 2014 20:46:17.0511 (UTC) FILETIME=[1DBBEB70:01CF3E34] This is a multi-part message in MIME format. ------=_NextPart_000_010A_01CF3DF9.73C90A60 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20 In addition to the gusset, I welding in a flex ball joint in one of the = pipes at the rear of the engine. It alleviated a crack problem area = that I was getting at the tail pipes where they hung from the engine = mount at the firewall. =20 Gary=20 LNC2 ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Wednesday, March 12, 2014 1:01 PM Subject: [LML] Re: Exhaust pipe failure The 3/4 exhaust system is hugely cantilevered. Long pipe sections at = the back end and each piece only has two bolts holding it to the engine = exhaust flange. This is unfortunately a recipe for cracks - and there = have been many. Since this entire exhaust layout is rigid, it really = needs a second support off the engine itself. Doing this will provide = immense support and take the load off of welds and the exhaust flanges. = =20 Cars provide a good example of exhaust design. The header and any rigid = pipes are firmly bolted to the engine block. A flexible joint then = transitions to the exhaust pipes that are hung off the bottom of the = car. The engine is free to move without imparting stresses to the = header. This arrangement is not foreign to aircraft, but the 360 = exhaust was designed without a flexible joint. If it had one, the aft = end could be supported by a flexible connection to the fuselage or = engine mount. I have seen a number of installations with a connection = between the rigid pipes and the fuselage or engine mount. With this = arrangement, any engine movement will put a load on the exhaust. = Effectively one has replaced loads generated by the mass of cantilevered = pipe subjected to vibration with loads generated by the pipes being = forced to move by the fuselage relative engine. Which is worse? Many = variables there. I suggest avoiding both sources of stress on the = exhaust and either supporting the pipes off the engine or adding a = ball-joint. On a related note. One of my pre-flight items is to grab the exhaust = and give it a good pull in all directions. Cracks take a while to = propagate around the circumference of the pipe. As they do, the = stiffness of the system will drop substantially. Any change in = resistance felt during this check is cause for further investigation. =20 Chris Zavatson N91CZ 360std http://www.n91cz.net/ =20 On Wednesday, March 12, 2014 8:31 AM, Gary Edwards = wrote: =20 That is the same joint I have had problems with in years past. On the = second weld repair of it, I added a half round gusset of exhaust tubing = at the front side of the joint. Haven't had any issues since...at that = location. =20 Gary LNC2 ----- Original Message -----=20 From: Greenbacks, UnLtd.=20 To: Lancair Mailing List=20 Sent: Wednesday, March 12, 2014 5:43 AM Subject: [LML] Exhaust failure... So much for our Bahamas adventure... Yesterdays's flight from KBVY to KOMN was uneventful until at 6k ft over = STARY Intersection, #4 exhaust fractured completely, lots unusual noise, = vibration and general banging around in the engine compartment. Brunswick Golden Isles BQK was the nearest. So 4ZQ is broken for the = moment but safely in a hangar there and I'm driving to West Palm this = morning with the broken exhaust bits. What I need at this point is a welder in the West Palm area who can work = his/her magic and try to make these whole again. If anyone here can offer a suggestion, please give me a call = 978-994-4564. Ideally, I want to replace this exhaust but a weld fix should get me = home in the meantime. The Lancair part # is EX-3/4-1 and according to Bill 5ZQ who made the = call for me, they don't have this and don't expect to. Angier Ames N4ZQ -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html ------=_NextPart_000_010A_01CF3DF9.73C90A60 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20
In addition to the gusset, I welding in a flex ball joint in = one of=20 the pipes at the rear of the engine.  It alleviated a crack problem = area=20 that I was getting at the tail pipes where they hung from the engine = mount at=20 the firewall.
 
Gary
LNC2
-----=20 Original Message -----
Sent:=20 Wednesday, March 12, 2014 1:01 PM
Subject:=20 [LML] Re: Exhaust pipe failure

The 3/4 exhaust system is hugely cantilevered.  Long = pipe=20 sections at the back end and each piece only has two bolts holding it = to the=20 engine exhaust flange.  This is unfortunately a recipe for cracks = - and=20 there have been many.  Since this entire exhaust layout = is=20 rigid, it really needs a second support off the engine=20 itself.  Doing this will provide immense support = and take=20 the load off of welds and the exhaust flanges.   =
Cars provide a good example of exhaust design.  = The=20 header and any rigid pipes are firmly bolted to the engine = block.  A=20 flexible joint then transitions to the exhaust pipes that are hung off = the=20 bottom of the car.  The engine is free to move without imparting = stresses=20 to the header.  This arrangement is not foreign to aircraft, = but the=20 360 exhaust was designed without a flexible joint.  If it = had one,=20 the aft end could be supported=20 by a flexible connection to the fuselage or engine = mount.  I=20 have seen a number of installations with a connection between the = rigid pipes=20 and the fuselage or engine mount.  With this=20 arrangement, any engine movement will put a load on the = exhaust.  Effectively one has replaced loads generated = by the=20 mass of cantilevered pipe subjected to vibration with loads = generated by=20 the pipes being forced to move by the fuselage relative engine.  = Which is=20 worse?  Many variables = there.  I suggest avoiding=20 both sources of stress on the exhaust and either supporting=20 the pipes off the engine or adding a ball-joint.

On a related note.  One of my pre-flight items is to = grab the=20 exhaust and give it a good pull in all directions.  Cracks take a = while=20 to propagate around the circumference of the pipe.  As they = do, the=20 stiffness of the system will drop substantially.  Any change = in=20 resistance felt during this check is cause for further=20 investigation. 

Chris Zavatson
N91CZ
360std
=
       =


On Wednesday, March = 12, 2014 8:31=20 AM, Gary Edwards <gary21sn@hotmail.com> wrote:
=20
That is the same joint I have had problems with in years=20 past.  On the second weld repair of it, I added a half round = gusset=20 of exhaust tubing at the front side of the joint.  Haven't = had any=20 issues since...at that location.
 
Gary
LNC2
-----=20 Original Message -----
Sent:=20 Wednesday, March 12, 2014 5:43 AM
Subject:=20 [LML] Exhaust failure...

So much for our Bahamas adventure...
Yesterdays's = flight=20 from KBVY to KOMN was uneventful until at 6k ft over = STARY
Intersection,=20 #4 exhaust fractured completely, lots unusual noise, vibration and = general=20 banging around in the engine compartment.
Brunswick Golden Isles = BQK was=20 the nearest. So 4ZQ is broken for the moment but safely in a hangar = there=20 and I'm driving to West Palm this morning with the broken exhaust=20 bits.
What I need at this point is a welder in the West Palm area = who can=20 work his/her magic and try to make these whole again.
If anyone = here can=20 offer a suggestion, please give me a call 978-994-4564.
Ideally, = I want=20 to replace this exhaust but a weld fix should get me home in the=20 meantime.
The Lancair part # is EX-3/4-1 and according to Bill = 5ZQ who=20 made the call for me, they don't have this and don't expect=20 to.

Angier Ames
N4ZQ


= --
For=20 archives and unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html
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