Originally Posted by
Bell_ringer
most regulators won’t allow you to factory build an aircraft and call it experimental.
Well, some do. So let's agree that regs differ around the world.
In any case, the concept of owner-built (and with it, the 51% rule) is
not to improve the quality of the aircraft. Most owners rightfully are wary about their ability to do a good job (follow MojoGrip on youTube if in any doubt). Here we speak about the market of non type-certified aircraft (NTCA), often referred to and labelled as "experimental". In this segment, the "factory-built" option attracts a premium over kit aircraft, as they are deemed to be the safer option.
The 51% rule only has to do with transfer of product liability from the airframe manufacturer to the client who - as nominal builder - now carries this liability. It is the high risk of litigation in some countries that has driven the cost of manufacturer's liability insurance to astronomical heights. By transferring this liability to the end client, NTCA manufacturers save on insurance premiums and can keep prices for their aircraft low.
Now, we always "want to have our cake, and eat it". I agree that some of these factory-assist plans are obvious schemes trying to reap the benefits of (almost 100%) factory-built while at the same time allowing to claim that the aircraft was majority-built by the owner.