The FAA issued draft Advisory Circular (AC) 21.93 “Determining the Classification of a Change to Type Design” last year to address the ongoing issue of whether a change to type design falls under the major or minor heading. The Modification and Replacement Parts Association (MARPA), in its comments on the draft AC, expressed the concern that the AC “appeared to introduce more uncertainty into the compliance equation, rather than resolving the compliance issues facing the industry.” Of particular concern, according to MARPA, is that the advice in the AC seems to suggest that some type design changes would require a supplemental type certificate, even if they clearly were not a major change in type design. With the announcement that the FAA plans to rewrite the AC, MARPA noted, “The [agency] took our industry’s comments seriously and withdrew the draft guidance so that it could make major improvements to it.” Some of MARPA’s suggested improvements are included in a
draft rewrite that it submitted to the FAA. The FAA’s new draft AC is expected to be published in the third quarter.