shipchief@aol.com wrote:

>
> Lynn,
> I think you are right about bolt material, I looked up grade 8 steel, it's
>only rated to 450 degrees F. 18-8 (304) stainless, although much weaker, has
>incredible temperature range .  It's rated for pressure vessel service to
>about 1300F and general use to 1690F.
> So I just  broke off a 1/16" drill in the head of an 18-8 stainless bolt,
>trying to make it accept safety wire. I'll keep working on that.
> I'm considering Inconel 600 hardware for the turbo inlet flange, it's rated
>to 2000F, but I'll try the stainless there for now, and watch it a lot.
> I plan to trim large diameter washers to fit tight against the turbo and
>header bodies, then after tightening the bolts, bend  the washer edge up to
>act as a lock tab.
>
>
>
> -----Original Message-----
>From: shipchief shipchief@aol.com
> To: Rotary motors in aircraft <flyrotary@lancaironline.net>
> Sent: Mon, Jan 27, 2014 7:22 pm
> Subject: [FlyRotary] Re: Exhaust Leak at Turbo Outlet Flange
>
>
> Dave;
> you pretty well summarized the problem.
> Ross the Subaru guy over on the VANs air force forum had valuable input as
>well.
> After I cleaned up and inspected the mess, installed grade 8 bolts and grade
>C high temp lock nuts on the turbo mount flange. I used the stainless
>embossed shim type gasket.
> I assembled the turbine exhaust - to - exhaust pipe flange W/O gasket, using
>1" grade 5 bolts that I had on hand. I used grade 8 washers, stacked based on
>the hole depth, they are not all the same depth.
> I removed the Kevlar exhaust pipe wrap, cut off an undamaged section, and
>stuffed it into the burned thru hole in the turbo blanket.
> I made exhaust pipe heat shields out of cut offs from galvanized building
>studs, left over from building my hangar.
> N89SE ran like a top, and made the 32 minute flight back to the Home Drome
>with no trouble.
> Today I shopped at the local specialty fastener store and picked up more
>Grade 8 hardware and some 1/16" cobalt drill bits, no one seems to carry
>drilled head grade 8 bolts around here.
> I brought the top cowl home to repair the heat damaged spot over the turbo.
>The repair might be an aluminum inspection door.
> Oh, one last thing; today I post flight inspected the repair, and all eight
>fasteners took 1/12th of a turn to re-tighten. I figure that's just thermal
>setting. Even if safety wired, they would need to be un-wired and re-torqued
>at least once?
> (I posted similar on the VANs forum, so you might see this over there too)
>
>
> -----Original Message-----
>From: Lehanover <Lehanover@aol.com>
> To: Rotary motors in aircraft <flyrotary@lancaironline.net>
> Sent: Mon, Jan 27, 2014 10:59 am
> Subject: [FlyRotary] Re: Exhaust Leak at Turbo Outlet Flange
>
>
>
> If you use locking nuts like Jet nuts that grip the stud, you just back out
>the stud on removal. Use the stock nuts or stainless nuts and safety wire
>them in the tightening direction. They never come loose and can be removed
>without drama. On my NA engines I use no exhaust gasket. Just a bead of GE
>100% silicone tub and tile calk. Keep it well away from the ports. Never had
>a leak, but I had no back pressure from a turbo hot section either. Might be
>worth a try.  
>
> Lynn E. Hanover
>
>
>
>
> In a message dated 1/27/2014 9:09:09 A.M. Eastern Standard Time,
>cardmarc@charter.net writes:
>  
>  
> I believe Mazda   uses some Inconel hardware on the 93+ 13Brew
>engines…………found this out the   hard and expensive way.
>  
> Marc
>  
>
>  
>From: Rotary motors in   aircraft [mailto:flyrotary@lancaironline.net] On
>Behalf Of David   Leonard
> Sent: Saturday, January 25, 2014 8:14 PM
> To:   Rotary motors in aircraft
> Subject: [FlyRotary] Re: Exhaust Leak at   Turbo Outlet Flange
>  
>
>  
>  
> Bummer!  Glad you are safe.
>  
>  
>
>  
>  
> I use the stock steel nuts.  Locknuts might be an   improvement but not if
>there is any non-steel component.  I did loose one   of those nuts once
>without to-do.  Not sure how long it was gone.    The other 2 held everything
>together.
>  
>  
>
>  
>  
> Be very careful with what gaskets you choose.  I found   some nice-looking
>aftermarket turbo manifold gaskets for about $20 while the   stock versions
>are about $90 each, so I installed one.  It lasted about   30 hours until it
>disintegrated.  The resulting exhaust leak burned   through a coolant line
>and I dead sticked onto a local airport (departing   from a formation routine
>at an airshow!..  complete with a cloud of   steam).
>  
>  
>
>  
>  
> Sigh, the stock ones are nothing but stainless steel   layer, not some sort
>of fiber stuff in the after market   ones.
>  
>  
>
>  
>  
> On another occasion I was using some very nice and   expensive exhaust
>clamps that were steel but I didnt notice that part of the   block holding
>the nuts was aluminum.  About 50 hrs in something caused   the alumimum to
>get too hot, which created an exhaust leak, which accelerated   the process.
> It burned a hole in the cowl and splatered molten aluminum   everywhere -
>some of it is still around.
>  
>  
>
>  
>  
> Another time I was using some fancy exhaust   wrap.  It slowly disintigrated
>over the course of 100+ hours and was   generally an annoyance.
>  
>  
>
>  
>  
> I tried a flowmaster hushpower muffler but melted most   of the stuffing out
>of it on the first flight. Luckily it melted pretty   cleanly and didnt clog
>the exhaust.
>  
>  
>
>  
>  
> Moral of the story..  as if it didn't take me long   enough to beat this
>through my skull..  NOTHING that is not made of   steel or better goes into
>any part of the exhaust system.  Particularly   gaskets and nuts.
>  
>  
>
>  
>  
> Guess I should have passed that one along sooner.    Glad you got back
>safely.  Good job.
>  
>  
>
>  
>  
> Dave   Leonard
>  
>  
> On Sat, Jan 25, 2014 at 5:14 PM, <downing.j@sbcglobal.net> wrote:
>  
>  
>  
>
>  
>    
>    
> I had the nuts     come loose on my turbo manifold on the block, I'm using
>with out     the turbo, so I drilled the nuts and secured them with wire.
>     JohnD
>    
>    
>    
>
>    
>    
> Thanks for keeping us all informed , helps us all to make     sure we look
>for often simple overlooked areas.
>    
>    
>
>    
>    
> Cheers
>    
>    
> Christian
>    
>    
> Renises 13 b rv7
>
> Sent from my     iPad
>    
>    
>
> On 26/01/2014, at 3:17     AM, shipchief@aol.com wrote:
>    
>      
>      
>      
> During the 8th       flight of my RV8 with 13B Turbo, I experienced an
>exhaust leak at the       turbo exhaust flange. I mistakenly used brass
>exhaust nuts  which are       twice as tall as regular nuts. They work great
>on most engines. I should       have know better, as the temperature at the
>turbo outlet, under the       insulation is much higher.
>      
>      
> The brass nuts       softened and deformed into a flange face at the washer!
>Once the tension       was gone, the heat & vibration did the       rest.
>      
>      
> The exhaust gasket       blew where the gap was widest, at the top.
>      
>      
> The escaping heat       burned thru the insulating jacket and the stick on
>reflective       aluminum. Then the fiberglass cowl charred, I smelled
>      that!
>      
>      
> I was close to my       destination, and high, so I was able to pull off the
>power, put down the       nosed and get on the ground without       incident.
>      
>      
> I'm disassembling       it now, looks like I need 4 high temperature lock
>nuts and a TO-4       exhaust flange gasket. I should review and improve the
>insulation over the       turbine housing. Also I need to repair the charred
>area of the cowl, which       might be in the form of an aluminum access
>      hatch.
>
>
>
>  
>
>
>
>
>