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From: Bob Tilley <btilley@mchsi.com>
Subject: Re: [FlyRotary] Re: Three candidates for Turbo Failure
Date: Mon, 12 Jul 2004 15:42:26 -0400
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>


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Ed and John,

So this brings us to what do we do now?

Test 1: install new modified turbo!  Check MAP to see if he is still 
producing to much boost.
I believe he should get some ramp-up of boost and it appears he is 
making to much.

Test 2: put a spacer in between the back cover of the turbo and the 
turbo, where the wastegate is located.
this will allow the wastegate to open farther.

Test 3: Remove the wastegate all together.

Test 4: Find a more suitable turbine wheel.

Bob

On Jul 12, 2004, at 12:45 PM, Ed Anderson wrote:

>
> 1.  we could have a condition whereby the turbine was not in the 
> "overspeed"
> territory but operating at a lower (safer speed) and a condition 
> existed
> that build up a deposit on the turbine wheel until its out of balance 
> state
> caused it to touch the housing and fail.
>
> 2.  A worn bearing ultimately resulted in failure due to wobbly and 
> wheel
> contact (Possibly acerbated by periods of long boost at high speeds - 
> but,
> not a true overspeed condition)
>
> 3.  Overspeed of the rotating assembly resulted in failure (due to 
> operating
> too far to the right on the compressor map possibly acerbated by the 
> leak in
> John's intercooler and/or BOV valve).
>
> 4.  Defective weld of wheel to shaft (Pretty remote chance - I believe 
> -
> especially with two turbos)
>
> 5.  Some combination of the above.  But, I believe that in all cases 
> higher
> turbine speed would acerbate the condition and lead to quicker failure 
> -
> whether true overspeed or not.
>
> Good addition to the theory stack, Bulent.
>
> Ed
>

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Ed and John,


So this brings us to what do we do now?


Test 1: install <bold>new modified</bold> turbo!  Check MAP to see if
he is still producing to much boost.

I believe he should get some ramp-up of boost and it appears he is
making to much.


Test 2: put a spacer in between the back cover of the turbo and the
turbo, where the wastegate is located. 

this will allow the wastegate to open farther. 


Test 3: Remove the wastegate all together.


Test 4: Find a more suitable turbine wheel.


Bob


On Jul 12, 2004, at 12:45 PM, Ed Anderson wrote:


<excerpt>

1.  we could have a condition whereby the turbine was not in the
"overspeed"

territory but operating at a lower (safer speed) and a condition
existed

that build up a deposit on the turbine wheel until its out of balance
state

caused it to touch the housing and fail.


2.  A worn bearing ultimately resulted in failure due to wobbly and
wheel

contact (Possibly acerbated by periods of long boost at high speeds -
but,

not a true overspeed condition)


3.  Overspeed of the rotating assembly resulted in failure (due to
operating

too far to the right on the compressor map possibly acerbated by the
leak in

John's intercooler and/or BOV valve).


4.  Defective weld of wheel to shaft (Pretty remote chance - I believe -

especially with two turbos)


5.  Some combination of the above.  But, I believe that in all cases
higher

turbine speed would acerbate the condition and lead to quicker failure -

whether true overspeed or not.


Good addition to the theory stack, Bulent.


Ed


</excerpt>
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