So my buddy ask me to go through the bottom end of the 360 on a Pitts he bought. Originally he was going to just do a top overhaul and leave the bottom alone since it was reported to run fine other than the front seal had a little leak. Somehow cooler heads prevailed.
I tore it all down and sent the hard parts off for inspection and wouldn't you know it, the crank failed. Below is the test image showing the crack between the lightening holes. You can't see this crack with the naked eye. Well you can but it just looks like someone scratched it with a paper clip or something. Regardless, I couldn't make it show up in a photograph.
There is more to the story here. The shop that did the inspection probably just quit looking when this crack was revealed since that is all that was in their report but when I got it back and started looking I found another crack located in the seal area. This one runs radially around the shaft and goes through to the inside of the hollow crank and is the cause of the persistent oil leak at the front seal. It is very likely that if this engine had been flown the front of the crank and propeller would have departed together in the not too distant future.
At least now there is a shiny new A4A crankshaft here that will be replacing the old cracked crank.
I tore it all down and sent the hard parts off for inspection and wouldn't you know it, the crank failed. Below is the test image showing the crack between the lightening holes. You can't see this crack with the naked eye. Well you can but it just looks like someone scratched it with a paper clip or something. Regardless, I couldn't make it show up in a photograph.
There is more to the story here. The shop that did the inspection probably just quit looking when this crack was revealed since that is all that was in their report but when I got it back and started looking I found another crack located in the seal area. This one runs radially around the shaft and goes through to the inside of the hollow crank and is the cause of the persistent oil leak at the front seal. It is very likely that if this engine had been flown the front of the crank and propeller would have departed together in the not too distant future.
At least now there is a shiny new A4A crankshaft here that will be replacing the old cracked crank.
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