It is not clear what certificate might be issued. The information that is provided in ACJ OPS 3.480(a)(1) and (a)(2) paragraph 2. depends upon an
assessment of 'engine isolation' that is described in AC 27 MG 3 - the preamble to which is shown below:
AC 27 MG 3. DEFINITION OF ENGINE ISOLATION FEATURES AS APPLIED TO §§ 27.79(b)(2), 27.141(b)(1), and 27.143(d)(1) (Amendment 27-19).
a. Explanation.
(1) Each of the cited performance and flight characteristic sections of Part 27 mention multiengine rotorcraft meeting transport Category A engine isolation requirements or refer to engine isolation features which ensure continued operation of the remaining engine. Unlike normal category fixed-wing (Part 23 § 23.903(c)) and the transport category fixed-wind and rotorcraft regulations, Part 27 does not provide a general engine isolation rule to make this determination.
(2) While it is clear that Part 27 does not require complete engine isolation, if credit for this feature is claimed (i.e., sudden complete engine power failure is not considered in showing compliance with the cited section), criteria must be established to allow a satisfactory isolation assessment.
(3) An approach which the FAA/AUTHORITY would find acceptable in making a Part 27 engine isolation determination is given. The FAA/AUTHORITY logic for establishing this criteria is also presented.
Jim