Cessna 208 and 208 b Deicing Boots

Comment on Docket No. FAA-2005-21275; Directorate Identifier 2005-CE-28-AD RIN 2120-AA64 The proposed action requires the installation of Cessna P/N SK208-146-2 on all affected airplanes. Any requirement that mandates the installation of a certain part numbered item to the exclusion of all other part numbered items is at variance with 14 CFR § 21.303. This section, known as PMA (an acronym for Parts Manufacturer Approval) provides an alternative mechanism for the design, production, sale and installation of aeronautical items other than those specified by the original equipment manufacturer. We suspect that the mandated installation of Cessna Accessory Kit AK208-6C may also require the installation of certain part numbered items. Comments: 1. While no alternative PMA parts are currently known to exist, they may be created in the future and the proposed regulatory action should take into account that possibility. 2. Because of the apparent conflict with 21.303 certain portions of the proposed action could be deemed by a competent court to be legally unenforceable. An action found to be unenforceable in part is generally also unenforceable in whole thereby invalidating the airworthiness directive. 3. While the existence of Alternative Methods of Compliance (AMOC) is permitted by the action, a part approved under 21.303 is already approved and may be used without further approval and is not, as some AD writers believe, an AMOC. Request: For all the above reasons, this commenter, Modification and Replacement Parts Association (MARPA), requests that the proposed action be modified by inclusion of the following or similar statement: "The requirement to install certain part numbered specific parts should be interpreted broadly to include any replacements parts approved under FAR 21.303 for the original equipment parts cited in this action. Nothing in this action prevents or precludes the installation of such alternatively approved parts." Jack Buster AD Committee