Originally Posted by SkylineAviation

I don't know specifically about a Citation 500 but many jet airplanes including types of citations can be flow single pilot 135. Part 135 Ops Specs A015 will authorize an "Autopilot in Lieu of Required Sencond-in-Command." Within the Ops Specs it will list the authorized aircraft approved by the FAA for the specific Part 135 company and the type of autopilot system used for the operation. If any "Additional Considerations/Limitations" are listed or needed for the type of operation or for that aircraft it will also be noted in the Op Spec. The autopilot Ops Specs authorizes single pilot IFR. FAR 135.105 also outlines this authorization.

An operation I flew for had a CE-510 as part of this Ops Specs authorization. Additionally, I don't know how Argus or Wyvern plays any part into this. Argus and Wyvern will still issue IS-BAO certification to companies flying single-pilot as far as I know, nor is insuring the aircraft a problem.