Unless something else happened to the flute in the interim, I’d say the cracks likely started out small and have simply progressed. It’s certainly possible and not at all unheard of.
That said, without knowing how the flute was packed and then impacted during the keyblock damage, I can only speculate. Certainly the socket/tenon cracks could have occurred at a different, more recent time as there are many ways it could happen.
Loren[/i]
Loren, thanks for the great informative posts!
Also, it’s just good to know you’re still around. 
–James
Thanks Loren and Jem. I’ll phone the MU as I am a member and see what’s what.
m.d.
Ouch! and commiserations, that’s awful. I’ve a vested interest here as I have Cotter keyless myself and would be devastated on discovering the same.
Just to check…
Upon cleaning the body I noticed that there are no fewer than FOUR cracks in the upper tenon
So, it’s not actually a ‘head and barrel combination’ as suggested earlier (i.e. the two head parts being joined and then subject to some localised lateral force). Although, if you have the same wooden coffin box that came with mine I’ve no idea how such a bending force could be applied in transit through the case (unless you don’t wrap it up and it rattles around inside?).
The cracks in the upper tenon of the main body seem harder to explain. But… I guess if the wooden case was dropped to the ground on its left-hand end there would be a pretty heavy linear collision between that tenon joint and the left end of the box (ditto for the headstock in the other channel of the box at the same time). That could be your cause - and well worth you (and me!) foam padding the ends.
My only other thought is that my Cotter (which is a joy and of which I can find no words of criticism) does get very ‘tight’ at that same cork tenon joint when it gets really warm, like sitting in a hot pub, and I’m a bit wary about separating it from the barrel until it’s cooled off a touch. The craftsmanship is excellent and part of that is Eamonn’s ability to turn a relatively thin wall on the body, which has a lightness to the tone without losing volume (at least when someone better than me plays it!). I guess it would also make it a bit more vulnerable to a heavy handed twist on a ‘tight’ day.
Anyway, no use crying over spilt milk. From the little I know about Eamonn Cotter, he’ll sort you out well in the end.
PS. I’m not sure I’d put any instrument through airline check-in baggage if it would fit in hand baggage.
That’s good advice, especially for an instrument as small as a flute. My stays in my backpack which fits nicely beneath the airplane seat in front of me. I wouldn’t trust anyone else with my flute…and it’s polymer so I have much less to worry about.
M.D. - I’ll keep my fingers crossed that you are back in business soon. Jem’s tip about the M.U. sounds like it may be of help to you!
Eric
Thanks guys, I appreciate it!
When the keyblock was broken the flute was in a tough wooden case inside a suitcase wrapped in clothes. Something got dropped on the suitcase hard enought to dent the flute case and break half a box of cds I also had in there.
m.d.