The FAA proposed to amend 14 CFR Part 39 with an AD for McDonnell Douglas Model DC-9-15F airplanes modified in accordance with supplemental type certificate (STC) SA1993SO; and Model DC-9-11-DC-9 12, DC-9-13, DC-9-14, DC-9-15, DC-9-15F, DC-9-21, DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, DC-9- 32F (C-9A, C-9B), DC-9-41, and DC-9-51 airplanes in all-cargo configuration. For certain airplanes, that action, published in the Federal Register on July 8, 2004 (69 FR 41204), proposed to require inspecting to determine the airplane's cargo configuration, and reporting findings to the FAA. For airplanes modified in accordance with a certain STC or with a cargo configuration that deviates from the as-delivered configuration, that action proposed to require revising certain manuals and manual supplements to specify certain cargo limitations. That action also proposed to require relocating all cargo restraints on the main cargo deck. \n\nComments \n\n\tWe provided the public the opportunity to participate in the development of this AD. We have considered the comments that have been submitted on the proposed AD. \n\nSupport for the Proposed AD \n\n\tOne commenter supports the intent of the proposed AD and concurs with the proposed actions. \n\nRequest To Revise Applicability Statement \n\n\tOne commenter, an operator, requests that we revise the applicability of the proposed AD. The commenter states that certain airplanes in its fleet were originally delivered as passenger airplanes but have been modified by various STCs to all-cargo configuration. None of these airplanes were modified in accordance with STC SA1993SO, and none has a main deck cargo door. The commenter notes that the Costs of Compliance section of the proposed AD indicates that a total of 33 airplanes worldwide (including 30 of U.S. registry) would be affected by the proposal. The commenter questions the accuracy of this number because it operates 74 airplanes in cargo configuration (including the airplanes described previously that were originally delivered as passenger airplanes). \n\n\tWe concur with the commenter's request to revise the applicability of this AD. Our intent was to make the requirements of this AD apply to airplanes delivered by the original equipment manufacturer (OEM) with, or modified by a third party to have, a main-deck cargo door that accommodates certain unit loading devices. Accordingly, we have revised the applicability of this AD to specify that this AD applies to Model DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, DC-9-15F, DC-9-21, DC-9- 31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, DC-9-32F (C-9A, C-9B), DC-9-41, and DC-9-51 airplanes in all-cargo configuration, and equipped with a main-deck cargo door. We have determined that only 8 of the commenter's 74 airplanes would be in this category. This AD also continues to apply to Model DC-9-15F airplanes modified in accordance with supplemental type certificate (STC) SA1993SO. \n\nRequest To Allow Records Review or Extend Compliance Time \n\n\tThe same commenter requests that we revise the proposed AD to allow determining the details of the cargo configuration from airplane records without performing the inspection of the main deck cargo compartment. The commenter states that it can determine the cargo configuration of its airplanes by reviewing the airplane records. The commenter further requests that we extend the compliance time from 60 days after the effective date to 6 months or longer after the effective date if we do not agree that a records review is an acceptable method of complying with the proposed requirements. The commenter states that the proposed 60-day compliance time would be unduly burdensome. \n\n\tWe do not agree that a records review is an acceptable method of complying with the requirements of this AD. We proposed this AD because we are aware that some airplanes delivered by the OEM in all-cargo configuration, with a main-deck cargo door, have been modified to a configuration similar to that provided by STC SA1993SO without any documentation in the airplane records. As explained in the proposed AD, the configuration provided by STC SA1993SO and similar configurations have deficiencies including inadequate design of the cargo loading system, inadequate loading procedures, and lack of identification of loading devices and restraining methods. We find that it is necessary to require an inspection of the main deck cargo compartment to determine the exact and accurate details of the airplane's cargo configuration. \n\n\tWe also do not agree to extend the compliance time beyond the proposed 60 days. As we explained in the preamble of the proposed AD, in developing the compliance time for the proposed actions, we considered the degree of urgency associated with addressing the subject unsafe condition, and the time that would be necessary to accomplish the proposed requirements. Based on these factors, we find that a 60- day compliance time for completing the required inspection and report represents an appropriate period of time for affected airplanes to continue to operate without compromising safety. Specifically considering the commenter's fleet, as we stated previously, only 8 of the commenter's 74 cargo airplanes are subject to the requirements of this AD. Therefore, we find that 60 days constitutes an appropriate compliance time in which neither safety nor the commenter's operations will be adversely affected. We have not changed the final rule in this regard. \n\nRequest To Limit Applicability of Manual Revisions and Cargo Restraint Relocation \n\n\tThe same commenter notes that the proposed manual revisions in paragraph (h) of the proposed AD do not take into consideration the different cargo zones and loading configurations for DC-9-30 and DC-9- 40 series airplanes. The commenter states that the requirements of paragraphs (h) and (i) of the proposed AD appear totarget a specific configuration and series, such as a Model DC-9-15F airplane modified in accordance with STC SA1993SO. The commenter wants the FAA to first accomplish a thorough evaluation of the details of each specific STC cargo configuration before subjecting an operator to a limitation on cargo loading, or a modification to the cargo configuration. The commenter requests that we revise the proposed AD to make paragraphs (h) and (i) apply only to airplanes that have been modified by STC SA1993SO, and to specify that requirements for other airplanes will be issued after an evaluation of the configuration details submitted as required by paragraph (f) of the proposed AD. \n\n\tWe do not concur. We have determined that the limitations stated in paragraph (h) and the requirements stated in paragraph (i) of this AD can be applied to most airplanes subject to this AD, regardless of model or configuration. Should an operator find that it is unable to comply with the specific requirements of this AD, that operator must request approval of an alternative method of compliance with the reporting requirements of paragraph (f) of this AD, as provided by paragraph (j) of this AD. We will determine whether or not the operator's fleet's cargo configuration exhibits the same unsafe conditions exhibited by airplanes modified in accordance with STC SA1993SO or airplanes in similar configurations. We have not changed the final rule in this regard. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments that have been submitted, and determined that air safety and the public interest require adopting the AD as proposed. \n\nCosts of Compliance \n\n\tThis AD affects about 3 airplanes of U.S. registry, out of 5 airplanes modified in accordance with STC SA1993SO worldwide. The following table provides the estimated costs for U.S. operators of these airplanes to comply with this AD. \n\n\tEstimated Costs--Airplanes Modified In Accordance With STC SA1993SOAction \nWork hours \nAverage labor rate per hour \nParts \nCost per airplane \nFleet cost \nManual changes \n1 \n$65 \nNone \n$65\n $195 \nRelocation of cargo restraints on main deck \n24 \n65 \nNone \n1,560 \n4,680 \n\n\n\tThis AD also affects about 27 airplanes of U.S. registry out of 28 airplanes worldwide that are in all-cargo configuration. The following table provides the estimated costs for U.S. operators of these airplanes to comply with this AD. \n\n\tEstimated Costs--Airplanes in All-Cargo Configuration \n\n\n\nAction \nWork hours \nAverage labor rate per hour \nParts \nCost per airplane \nFleet cost \nInspection/Reporting \n8 \n$65 \nNone \n$520 \n$14,040 \n\nAuthority for This Rulemaking \n\n\tTitle 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority. \n\n\tWe areissuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, "General requirements." Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. \n\nRegulatory Findings \n\n\tWe have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. \n\n\tFor the reasons discussed above, I certify that this AD: \n\n\t(1) Is not a "significant regulatory action" under Executive Order 12866; \n\n\t(2) Is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. \n\n\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD. See the ADDRESSES section for a location to examine the regulatory evaluation. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Safety. \n\nAdoption of the Amendment \n\nAccordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n2. The FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD):