Re: Can't believe what was in the exhaust port!
The 235 style motors have the "tuned" exhaust and inside the back of the block in the exhaust area are "stuffers". The theory is that they act like headers to tune the exhaust. If the motor is being lugged it's possible to melt off a piece due to high combustion temps. It's most likely a piece of one of the stuffers.
This seems like the most logical possibility. The piece in the photo looks like it is a chunk of melted alumnum block, to me. As for the shiny appearance, that is exactly what I would expect of a piece of aluminum that has been burnished in any way, such as being rubbed against the inside of the exhaust hub of a gearcase, to look like. In fact, you can polish a piece of aluminum sheet to look like chrome. A good example of this, is the polished intakes on a Blue Angels jet.
..... reminds me of an incident we had back in the 90's, a GE CT7-9 engine with less than 200 hours on a Saab 340B failed catastrophically just after take-off. The lab found an alloy foreign to the engine, but commonly used in the manufacture of tools.......
I had to smile at this one, because most people will think you are talking about a car, rather than a twin engine, turboprop aircraft. BTW, that "tool material" that was found, was most likely what was left of an impact driver tip. They are made of hardened steel and having someone leave one in the intake of an engine, is not uncommon. I once watched an Allison T-56 on a C130 Hercules tear itself up, after ingesting one on engine startup. Once it started shredding compressor blades, the engine became so unbalanced that the motor literally looked like it was going to come off of the airplane. In fact, the prop spinner
did come off!
???
