"Brian Whatcott" schrieb im Newsbeitrag
news ....
It would be helpful to know if there are any more samples of this airplane
design flying,

yes there are and no engine mounts broke (in normal flight) until now (as
far as I know)

and in particular, are there any more examples of this engine mount in
existence?

yes, several

If there ARE, then that would focus the debate onto material defect or
construction defect or test rig defect.

I suppose a testrig issue. Load concentrations build up which do -not-
happen in real flight scenarios (my various previous posts about static load
testing)

Richard reminds us that you didn't see a permanent distortion of the
mount - which is the desired failure mode (supposing that any failure is
desirable) but a clean break - presumably two clean breaks. That should
not happen, ever on a test.

interesting aspect.

Note: because of legal coniderations I will not mention company names,
people's names or types or designations of aircraft here.

--
P.S.
what me -really-surprised is the fact that for about a minute the mount held
the engine more or less in place even with this two severe cracks! 4130 is
really good stuff...