Gang: Pardon me for switching this comment to US C-130 transports (with four powerful Allison turboprops), but years ago, the C-130 A through H models had NO standby horizons, and if you lost all generators, you might not make it. There was also no battery back-up source for the AC or the copilots' horizons.
My father lost all electrics twice, in night IMC (instrument weather), during stable climb-out or cruise conditions, with no prior electrical faults. The first time in an A model, and later in an E. Thank God they had highly-experienced Flt. Engineers who could reset generators etc quickly, with a flashlight focused on the Aircraft Commander's ADI (horizon). Those cheap penny-pinching SOBs back then in our Pentagon could not "justify" the expense for many years. Another such Air Force Reserve C-130 (Colorado Springs) crew supposedly recovered control from a spiral in IMC over Hawaii only after they broke through an undercast-very nice job, John and crew.
Even civilian Lockheed Electras were "grandfathered in", per our wonderful FAA (safety first...well...), with no back-up horizon needed, which could have had a battery source. Zantop lost such an Electra and the crew when a mistake was made during an electrical fault over Utah in IMC. There must have been, maybe there still are many passenger/cargo planes in the USA which have no such back-up power sources.
[ 05 November 2001: Message edited by: Ignition Override ]