Hi Ronald, I agree with another poster, I don't really see the issue here.   If an EGT starts going wild I wouldn't pull a jug and I certainly wouldn't change the engine.  Deposits are normally found so that isn't a reason either.    TCM has a large section on checking for problems starting with the EGT probes and going from there.  To pull cylinders first and swap out to an Allison makes less sense than trying to verify the EGT issue in the first place.  Swapping a probe comes to mind and is somewhat less expensive and doesn't require surgery on the patient.  And they recommended pulling cylinders based on what?  And how many hours on the engine because now you have to be absolutely sure the crankcase halves don't fret and cause more problems.  Been there, done that.  Make sure they check the SBs on that subject before you fly again.

Paul
Legacy (and two dogs with lots of brown deposits)
On 2012-08-19, at 9:36 AM, Ronald STEVENS <Ronald@sdc.com> wrote:

> Hello guys
>
> Well, this is one the reasons why I am thinking of replacing my engine with a turbine lol
>
> Anyway, we are scratching our heads here. We found (looks like lead) deposits inside the cylinder and on top of the pistons. It is pretty soft, some parts are harder (probably baked) and you can actually take a harder sponge and start cleaning lol
>
> But why?? Why did this happened?? I mean I am thinking I am always driving my engine according to the 'gospels', Full rich in climb and take off, never over powering (using MAP 31-34 in climb), then level off, go back to MAP29, lean to 16.5, bump it up to MAP31-32 with approx. 18GPH/2500 RPM
>
> Always checking for CHT, (cruise temps are approx. 370), TIT=1610
>
> So.....then suddenly my EGT (not CHT) starting to act up, and showing a HOT warning, me adding mixture to full rich, EGT back to normal, this happened twice on the same cylinder, so I requested a borescope and found this.....so we pulled the jug.
>
> Now I can pull them all, clean them all, and wait for the next time?? Why could something like this happen? (I even heard someone telling me that I was leaning too much??)
>
> Any idea ??
>
> Thanks -- Ronald
>
> ps Pict 3 showed some of the stuff that we were able to scrape off, and in the upper left corner you see the hot spots, they are colored but the 'skin' feels the same, so it looks like material was coming off or burned in, but it is not, it is the deposit on top.
>