View Full Version : Presume this crankcase is history?

28th April 2012, 18:26
see photos attached...

Attached files http://cloudniner.co.uk/images/converted_files/114333=8501-apdc0125.jpg (http://cloudniner.co.uk/images/converted_files/114333=8501-apdc0125.jpg) http://cloudniner.co.uk/images/converted_files/114333=8502-apdc0124.jpg (http://cloudniner.co.uk/images/converted_files/114333=8502-apdc0124.jpg) http://cloudniner.co.uk/images/converted_files/114333=8503-apdc0123.jpg (http://cloudniner.co.uk/images/converted_files/114333=8503-apdc0123.jpg)

28th April 2012, 18:44
nice pictures, but what type of engine it is, and aircraft?

Please en light us all.

28th April 2012, 19:08
It's a 503 from a T600, 1550 hours (ish)

Dave Smith
29th April 2012, 13:41
Some more info?
Got a picture of it installed?

29th April 2012, 20:29

No picture of it installed, sorry. The engine was running ok (a bit rough near idle rpm which I could not manage to tune out) but in need of a rebuild. On taking it apart I discovered the head gaskets were leaking, the barrels were worn and in need of a rebore (Some quite deep scoring on them so not totally sure if a rebore would do it), I didn't bother much with the pistons after examining the barrels. The crankshaft oil seals were leaking, well, mag for sure, but the gearbox oil was very dark so possibly the PTO seal as well. On cleaning the crankcase I noticed what look like cracks in the photos which are coming from the gearbox mounting holes. Don't know how deep they are, certainly not through the full width of the case where I could see. But to me they look like cracks and that is enough to make me seek advice. I'm going to run them past my inspector later in the week but posting them here is 5 mins work so no harm in asking others with more experience than me.


30th April 2012, 06:37
Look like cold casting cracks at first glance and may have been there since day one: Its a choice, on the one hand if they have been there since day one and have not gone right through they could be good for another 500hrs, the casting has normalised, all stresses dissapated, however, the perceived wisdom is that cracks grow. I would not risk it as I find flying with clenched buttocks uncomfortable.

Dave Smith
30th April 2012, 10:01
Really difficult to asses without looking at. I still can't envisage what actually bolts into those holes...
If you dressed the alloy down to smooth and then did a dye penetrant crack test, you could at least see if they are actual cracks or just mould marks.

From your description, it sounds like the engine has reached a well deserved retirement anyway...


Mr no limit
30th April 2012, 14:08
I donít think they are cracks at all. I believe they are just casting marks.

3rd May 2012, 18:12
Pictures 1 and 3 are definitely casting marks. I have them on my 503 crankcase too in the same positions. I suspect 2 is similar. If you want to satisfy yourself you could perhaps rub them down with wet and dry paper on a sanding block (but not so as to damage the gearbox mating surface) and see if they disappear. I suspect they will - indicating that they are not at all deep.

4th May 2012, 10:24
Thanks guys Just to update my inspector and another venerable aircraft engineer took a look at them. They thought it would be unusual for the crankcase to be cracked in this way but after much peering and rubbing of chins suggested a dye test to be sure.

Like you Tom I can convince myself that a couple of them might be casting marks but there is still one that I can't so better to be safe than sorry.

How is your rebuild going?

5th May 2012, 21:31
Progress is steady but slow, thanks Simon.

Spent last week checking out possibly corroded big end bearings (turned out to be Loctite contamination thank goodness) and assessing the crankshaft ball bearings (they are a C4 fit so some play is to be expected). Hopefully I'll get most of the engine back together over the bank holiday.

Hope your crankcase checks out ok.