A few basics.. I am an LAE working for an airline, so do have a little knowledge on Air legislation.

If you wish to take passengers paying full fare as revenue service, you need an Air Operators Certificate. The regulations and requirements to get that since the early 2000’s are EU driven if your aircraft is over 5700 Kgs maximum take off mass. The Air Navigation Order has been amended to match the EU regulations on this. EU regulations also now apply to passenger aircraft at 2350 Kgs MTOM as well now. That is outside of the day job knowledge but would be fairly similar.

Non EASA regulated civil frames come under the British Civil Aviation Regulations (BCAR’s). These cover the ex military war birds and jets. If you have a Spitfire etc. That is a simple complexity airframe. No OEM requirements for support however the maintenance schedule must be no less restrictive that the basic requirements of LAMS. The CAA decide on the level required to award the PtF (annual and case by case basis). Hunters, Canberras, Se Vixens etc, are intermediate. They have higher performance and more complex systems such as hydraulically ASSISTED controls. However the aircraft have manual reversion of these controls. The terms of the PtF are more restrictive to maintenance and operating conditions.

If you have a frame that has thrust augmentation (reheat), auto stabilisation or autopilot and fully powered flying controls with no manual reversion, the frame is classed as complex requiring OEM oversight, fairly rigid maintenance and operations structures similar to in service and also the CAA will investigate the technical safety record of the aircraft in military service prior to awarding the PtF. The Lightning had an awfully high accident ratio due to technical failures. The CAA know that. The Vulcan proved it could be done and the Swedish Historical Flight dispel “the reheat is banned in private aircraft in the UK sketch”. SAAB still act as OEM for the SHF Viggen and Draken. 😀