Maybe RVDT can explain if there is a difference between a Police Helicopter (Mission Bus) and a normal 135?
DB,
Wander out to your particular 135 and gaze up at the Overhead Panel. Observe carefully. All will be revealed. CB's on the SHED BUS 1 and SHED BUS 2 will tell you what is what.
Also take note of AVIONIC SHED BUS 1 and AVIONIC SHED BUS 2 - items listed there will be avionics that get shed and will vary amongst serial numbers and roles as you imply.
You will note on a
standard glass cockpit (MEGHAS) aircraft that you will lose SEARCH LIGHT (not landing light), RAD ALT, AFT FUEL PUMP.
Avionics can vary considerably but I would suspect that you will still lose all mission radios and COM 1 at the minimum. In Sid's case he appears to still have the RAD ALT. He could have a steam gauge aircraft which obviously has
a lower consumption and it is feasible.
Each 135 has it's own unique Avionics Manual applicable to that serial number. On the one I operate it is 284 pages and covers specific customer avionics only - the generic avionics are in the AMM.
The SHED BUS is there for total loss of DC Power Generation and the requirement to be able to continue for a specified period of time on the battery and dumps it automatically for you.
Be aware that if you do get the opportunity to fiddle with a live aircraft and decide to power it all up to see for yourself, with Ground Power connected the SHED BUS and High Power Consumers
WILL be powered.
While you are at it review the procedure in the RFM
pre-flight w.r.t. checks of the BUS TIE's and SHED BUS. It often gets missed and I actually do it as part of the pre-start.