A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-8 series airplanes that have been converted from a passenger-to a cargo-carrying ("freighter") configuration was published in the Federal Register on September 27, 2000 (65 FR 58203). That action proposed to require, among other actions, modification of the main deck cargo door structure and fuselage structure; replacement of fasteners in the two door-side hinge elements; modification of the main deck cargo floor; and installation of a main deck cargo 9g crash barrier. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\nRequest To Revise Compliance Times \n\n\tOne commenter requests that the compliance times specified in paragraph (b) of the proposed AD be revised from "Within 2 years or 2,000 flight cycles after the effective date of this AD, whichever occurs first" to "within 3 years or 4,000 flight cycles after the effective date of this AD, whichever occurs first." The commenter contends that if the inspection and evaluation required by that paragraph reveals a discrepancy, the corrective modification will be extensive. The commenter states that such an extension would allow operators to correct discrepancies at one maintenance visit, and thus, minimize airplane downtime. \n\n\tThe FAA agrees. Since issuance of the NPRM, we have gained a better understanding of the design feature of the original modification relative to the vertical side restraint installation and decompression venting. We have determined that the structure is sufficiently robust, and that accomplishing the required inspection, evaluation, and modification, if necessary, required by paragraph (b) of this AD "within 3 years or 4,000 flight hours after the effective date of this AD, whichever occurs first," will provide an acceptable level of safety. For the same reasons, we also find that the 2-year compliance time for the modification required by paragraph (e) of this AD can be extended to "within 3 years or 4,000 flight hours after the effective date of this AD, whichever occurs first." Therefore, we have revised the compliance times of paragraphs (b) and (e) of the final rule accordingly. \n\n\tThe same commenter requests that the compliance time specified in paragraph (f)(2) of the proposed AD be revised from "Within 2 years or 2,000 flight hours after the effective date of this AD, whichever occurs first" to "within 3 years or 4,000 flight cycles after the effective date of this AD, whichever occurs first." The commenter states that postponing the replacement for another year will not adversely affect safety, because incorporating inspections into the operator's FAA-approved maintenance or inspection program within 1 year, as required by paragraph (a)(1) of the proposed AD, will provide an acceptable level of safety. The commenter also states that a 3-year compliance time would allow it to perform the proposed replacement concurrently with the major rework on the door structure, and thus, reduce airplane downtime. \n\n\tBased on the commenter's reasons, the FAA agrees to extend the compliance time for the replacement required by paragraph (f)(2) of this AD. Extending the compliance time to "within 3 years or 4,000 flight cycles" will not adversely affect safety and will allow the replacement to be performed at a base during regularly scheduled maintenance where special equipment and trained maintenance personnel will be available if necessary. We have revised paragraph (f)(2) of the final rule to specify a compliance time of "within 3 years or 4,000 flight cycles after the effective date of this AD, whichever occurs first." It should be noted that we inadvertently used "flight hours" instead of "flight cycles" in paragraphs(f)(1) and (f)(2) of the NPRM. Therefore, we have revised that term to read "flight cycles" in paragraphs (f)(1) and (f)(2) of the final rule, as was used in other paragraphs of the NPRM. \n\nRequest To Provide an Alternate Means of Compliance \n\n\tThe commenter also requests that paragraph (a)(2)(i) of the proposed AD be revised to include an option that states: "Main deck zone loading can be limited as approved by manager LA ACO in such a manner that no modification is required for the main deck floor structure. This will eliminate the requirement for Alternate Means of Compliance." The commenter notes that under the heading "3. Capability of the Unmodified Floor" in the preamble of the proposed AD, it states "It is also possible to limit the main deck zone loading to a level that the main deck cargo floor can be supported safely without modification." The commenter states that the analysis performed by the DC-8 Cargo Conversion Joint Task Force and FAA has shown that the main deck floor modified per Supplemental Type Certificate (STC) SA1802SO or SA421NW is capable of carrying the zone loads equivalent to Aeronavali modified airplanes. \n\n\tThe FAA consulted with the commenter to clarify its reference to paragraph (a)(2)(i) of the proposed AD. The commenter meant to refer to paragraph (c) of the proposed AD. We do not agree with the commenter's request to revise paragraph (c) of the final rule. We find that the option suggested by the commenter would require operators to obtain a separate approval from the Manager of the Los Angeles Aircraft Certification Office (ACO). Adding the commenter's statement in the AD would not save us or the operators any resources, because, like the requirements of paragraph (c) of this AD, it also would require operators to submit a letter and substantiating data to us for review. The difference between the two letters would be in name only (i.e., alternate method of compliance vs. approved method of compliance). Therefore, no changeto paragraph (c) of the final rule is necessary. \n\nApproval of Supplemental Type Certificate (STC) \n\n\tSince issuance of the NPRM, the FAA has reviewed and approved STC ST01181LA (held by Structural Integrity Engineering (SIE)). We find that this STC provides an acceptable means of compliance with the requirements of paragraphs (a) through (g) of this AD. Therefore, we have revised the final rule to include a new Note 2 to reference the applicable STC as a source of service information for accomplishing the requirements of paragraphs (a) through (g) of this AD. \n\nConclusion \n\n\tAfter careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\n\tThere are approximately 32 Model DC-8series airplanes of the affected design in the worldwide fleet. The FAA estimates that 29 airplanes of U.S. registry would be affected by this proposed AD. The following table shows the estimated cost impact for airplanes affected by this AD. The average labor rate is $60 per work hour. The estimated maximum total cost for all airplanes affected by this proposed AD is $6,718,140, or $231,660 per airplane. \n\n\nAction\nWork hours\nParts cost (estimated)\nTotal cost (estimated)\nIncorporation of inspections into maintenance or inspection program.\n 8\nN/A\n$13,920, or $480 per airplane.\nModification of main deck cargo door structure and fuselage structure. \n1,420 \n$6,500\n$2,659,300, or $91,700 per airplane.\nInspection of exposed surfaces of main deck cargo door hinge.\n16\nN/A \n$27,840, or $960 per airplane.\nReplacement of the existing fasteners in the two door-side hinge elements.\n 60\n$100\n$107,300, or $3,700 per airplane.\nInspection and evaluation of the cargo handling system.\n16\nN/A\n$27,840, or $960 per airplane.\nModification of main deck cargo floor\n40 \n$500\n$84,100, or $2,900 per airplane.\nInspection and evaluation of the venting system.\n16\nN/A\n$27,840, or $960 per airplane.\nInstallation of main deck cargo 9g crash barrier. \n1,500\n$40,000\n$3,770,000, or $130,000 per airplane.\n\n\tThe cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have a substantial directeffect 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\n\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Safety. \n\nAdoption of the Amendment \n\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n\t1. 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\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: