The airplane had an Electric AC powered Attitude Indicator and HSI and a 28 volt turn and bank on the left side all of which were not powered with the battery master off. It did not have co-pilot gyro instruments
Wow. Was the plane legal with the right side gyros removed? Is there some Canadian equivalent of "GRABCARD"?
I'm a big fan of having as many redundant attitude systems as possible. Am much happier doing instrument flying at night in a 172S rather than a classic 172N or P due to the second vacuum pump (yes, connected in series, but nevertheless). Having an auxiliary electric vacuum pump is also great, as is one of those fancy handhelds with an OBS display allowing you to shoot an ILS in the event of a total electrical failure.
ForeFlight coupled to a Sentry module (or similar) giving rudimentary GPS-based attitude and heading is also good weapon of last resort.
Thanks for sharing this!