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 Fokker Model F28 Mark 0100 series airplanes was published in the Federal Register on January 19, 1996 (61 FR 1294). That action proposed to require installation of reinforcement plates under each hook latch fitting on the frame of each large cargo door. For some airplanes, the action proposed to require inspections to detect cracking in the area around each hook latch fitting, and repair, if necessary.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Support for the Proposal
Two commenters support the proposed rule.
Request to Extend Proposed Compliance Time for Installation
One commenter requests that paragraph (a) of the rule be revised to extend the compliance time for accomplishing the installation. The commenter requests that the proposed compliance threshold of 11,000 flight cycles be extended to 16,000 flight cycles, and that the proposed "grace period" of 500 flight cycles (after the effective date of the AD) be extended to 2,200 flight cycles. This commenter, a U.S. operator, requests this extension so that its remaining fleet of affected airplanes can be modified during a regularly scheduled "Q" check (which occurs at approximately 16,000 flight cycles), and so that this operator can avoid special scheduling of airplanes, which would entail considerable expense over that estimated by the FAA's cost impact analysis. This commenter considers the extension justified because:
1. no cracks have been found on any of the airplanes that it has modified so far, which have accumulated an average of 13,755 total flight cycles; and
2. the proposed compliance threshold was based on only test data and not on in-service experience.
The FAA does not concur with the commenter's request to extend the compliance threshold. The proposed compliance time was developed not only in consideration of the urgency of the safety implications, but in consideration of normal maintenance schedules for timely accomplishment of the modification, and the recommendations of both the airplane manufacturer and the Netherlands airworthiness authority. The FAA determined that 11,000 flight cycles is the maximum acceptable threshold for accomplishing the installation without the need for additional inspections. Any cracking that may develop in the subject area during the period up to the accumulation of 11,000 total flight cycles on the airplane can be fully repaired with the accomplishment of the installation described in Fokker Service Bulletin SBF100-52-050, Revision 1. However, if cracks are not detected and repaired by the 11,000-flight cycle threshold, they could grow to lengths such that the installation would not be sufficient to ensure the long-term structural integrity of the area associated with the cargo door frame, and may even necessitate the replacement of the complete door frame.
In addition, if the compliance threshold were extended beyond the 11,000-flight cycle threshold to 16,000 flight cycles as requested by the commenter, the FAA would find it necessary to require operators to conduct inspections (to detect cracking) during the extended period. Each inspection of the area would take approximately 4.5 hours to accomplish, which is the same amount of time required to accomplish the installation itself. Therefore, delaying the threshold for the installation to 16,000 flight cycles by performing necessary repetitive inspections in the meantime would not reduce operators' workload or costs.
However, the FAA does concur with the commenter's request to extend the "grace period." The FAA has determined that the proposed "grace period" of 500 flight cycles may be extended to 1,200 flight cycles, without the need for repetitive inspections beyond the inspection specified in paragraph (b) of the final rule. The FAA bases this determination not only on the safety implications associated with the unsafe condition, but on recent in-service data and inspection results. Accordingly, the FAA has revised paragraph (a) of the final rule to specify a "grace period" of 1,200 flight cycles.
Conclusion
After 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.
Cost Impact
The FAA estimates that 100 airplanes of U.S. registry will be affected by this AD, that it will take approximately 4.5 work hours per airplane to accomplish the required installation, and that the average labor rate is $60 per work hour. Required parts will cost approximately $10,000 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $1,027,000, or $10,270 per airplane.
The FAA estimates that it would take approximately 4.5 work hours per airplane to accomplish the required inspection (that is required for certain airplanes), and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the required inspection on U.S. operators is estimated to be $270 per airplane.
The 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. However, the FAA has been advised that the required installation already has been accomplished on at least 8 affected airplanes; therefore, the future cost impact of this AD is reduced by at least $82,160.
Regulatory ImpactThe regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
For 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."
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, 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:
PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: