Rantanplane,
By any chance, could the view onto the cad in the ec135 have been blocked accidently with some equipment, a map or whatever (- if it was working correctly)? Pilots admitted they had simply forgotten about the main tank pump which I understand was to be switched on after starting the engines with only prime pumps on. Then they simply could not see the caution coming on, and they were not aware of it. P1 flying with NVG's and P2 operating the searchlight - all eyes focused to the outside of the cockpit.
Good point, there is a Velcro held placard panel on the upper part of the instrument panel (sun hood) that can and does fall down and obscure the CAD & part of the warning panel. However, any cautions that appear would still illuminate the master caution light in front of the pilot and the audio would still alert the crew.
There is always the possibility that any cautions were automatically & immediately cancelled, habitually. If the CAD was indeed obscured by this panel, perhaps no real check of the indications or fuel was made as it wasn't realised that the panel was obscuring the warnings, cautions & fuel indication and as such everything 'appeared normal'.
It usually makes a noise when it falls down, but it's a noisy environment.
http://adradvocacy.files.wordpress.c...135t3panel.jpg