From the FAA document:
Five operators requested that we remove the requirement for replacing the blades for the R44 Astro models, because these models are not equipped with hydraulic assisted controls and the new blades cannot be installed on these models unless the helicopter is converted to hydraulic assisted controls, a costly conversion which is not necessary for safe flight. These commenters further stated that the conversion is not only an additional expense but also can only be performed at the Robinson factory. One commenter believed the new blades are compatible with the non-hydraulic airframe and requested we require that Robinson test the new blades on the non-hydraulic R44 Astro airframe, so that the new blades can be installed on the R44 Astro without also having to convert the helicopter. The commenters also stated that Robinson then reserves the right to upgrade any component on the helicopter to their latest revision even though there is no AD or SB stating the Robinson required change, and this Robinson requirement results in additional cost increase.
Although I personally hate flying Astros I don't think it's fair to make Astro owners upgrade to hydraulics, and certainly I don't believe it's cool that Robinson reserve the right to upgrade any component on the helicopter to latest revision without an AD or SB. It totally seems unfair that due to Robinson's inability to produce a reliable rotor blade (though they've been trying unsuccessfully for 30 years) that an Astro owner might also have to replace other components unrelated to the rotor system while trying to keep his aircraft airworthy.
I'm not sure why Robinson won't allow the blades to be installed on an Astro without hydraulics. Is it simply that they want to avoid the cost of flight test on that airframe? Given that it is
their bad blade design that is behind this AD it seems quite reasonable for them to have to go the extra mile to keep the Astros flying without requiring upgrade to hydraulics. And finally, if there really were no way to avoid that, then at least they should be limited to changing only those components on the helicopter related to mounting the hydraulics, and not be allowed to change unrelated components on the helicopter as part of the upgrade.