Maybe the engine sag or speculated broken motor mount caused the canopy to unlatch through some torque or twist imparted to the firewall and/or fuselage, i.e., the canopy unlatching was a symptom of a bigger problem …

 

Dana

 

 

Paul may be on to something.  I looked at the original picture sent by Tom and if you look at the bottom of the spinner (not the top), it looks like it extends beyond the cowl.  In the other picture of the plane on the ground there was some sag, but not enough to bring the spinner below the cowl line.  A broken engine mount?  Maybe the canopy being unlatched had nothing to do with it except to cause a distraction.  Normally, a slight nose-down thrust vector is a stabilizing influence, not destabilizing.  As I understand it the plane had low hours, so the fatigue failures of mounts we have seen shouldn't have been a factor.