Heck, in it’s day this thing was a death trap.
It was heavy, slow, underpowered, but on par with other planes of its era.
Mechanical failure ? Possible, but I'm guessing pilot error - flying low through a pass as passengers oohed and ahhed at the scenery. Hot, thin air, full load, and unturbocharged engines meant they couldn't clear the mountainside at the end of the pass (just like the CO crash I cited)