A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 94-21-02, amendment 39-9043 (59 FR 51361, October 11, 1994), which is applicable to all Dornier Model 328-100 series airplanes, was published in the Federal Register on June 17, 1997 (62 FR 32699). The action proposed to supersede AD 94-21-02 to continue to require repetitive tightening of the screws and quick-release fasteners on the wing/body fairing panels. For certain airplanes, the proposed AD also would require the installation of new fastener systems for those panels, and the application of new torque values. Accomplishment of these actions would terminate the requirement for repetitive tightening of the screws and fasteners of those airplanes. In addition, the proposed AD would limit the applicability of the existing AD by removing certain airplanes.
Comments
Interested persons have been afforded an opportunity to participate in the making ofthis amendment. One commenter, an organization representing regional airlines, responded to the invitation for comments extended in the proposal to amend part 39. Due consideration has been given to the comments received from that commenter.
As noted above, the proposed AD would require, for certain airplanes, the installation of new fastener systems and application of new torque values for the affected panels. Upon completion of those modifications, the requirement presently contained in AD 94-21-02 for repetitive tightening of the screws and fasteners would be terminated. Instead of this required terminating action, the commenter requests that those modifications be approved as an optional terminating action. Operators could then choose to complete those modifications or continue performing the inspections presently required by AD 94-21-02. The commenter contends that the inspections currently mandated by AD 94-21-02 have been shown to be highly effective in responding to the airworthiness concern addressed in this AD. The commenter adds that the subject fasteners are highly visible. In addition, the mandated inspection also is supplemented by general daily inspection of the panels. Although the commenter indicates that accomplishment of the modification is critical for continued airworthiness, the ability to accomplish the required inspections, as well as a lack of in-service findings, support the contention that inspections should be allowed to continue.
The FAA does not concur with the commenter s request. The FAA has determined that long term continued operational safety will be better assured by modifications or design changes to remove the source of the problem rather than by repetitive inspections. Long term inspections may not be providing the degree of safety assurance necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with numerous repetitive inspections has led the FAA to consider placing less emphasis on special procedures and more emphasis on design considerations. The FAA, therefore, does not concur that continued reliance on the inspections presently required by AD 94-21-02, as suggested by the commenter, would provide an adequate level of safety.
The commenter also requests that if continued reliance on the inspections presently required by AD 94-21-02 is not permitted, the compliance period for the required modifications should be extended to 24 months after the effective date of the AD. In that regard, the commenter presents economic data provided by an operator of affected aircraft.
The commenter states that the cost impact information contained in the proposed rule only identifies eight affected airplanes. However, the commenter indicates that one operator alone operates 13 affected airplanes, and estimates that, if a 12-month compliance time is adopted, the cost of retrofit for that operator will be over $200,000, including disruption to its airline schedule.
The FAA concurs with the commenter s request to extend the compliance time for accomplishment of the modification. The cost impact of the proposed AD was based on the assumption that eight airplanes would be affected. As the commenter notes, there are now considerably more affected airplanes in service. In light of this, the FAA has revised the cost impact information, below, to specify that 29 airplanes of U.S. registry will be affected by this AD.
The FAA's intent was that the modification be accomplished during a regularly scheduled maintenance visit for the majority of the affected fleet, when the airplanes would be located at a base where special equipment and trained personnel would be readily available, if necessary. Based on the information supplied by the commenter, the FAA now recognizes that 24 months will allow the majority of affected operators to accomplish the modification within regularly scheduled maintenance visits. The FAA has revised paragraph (b) of this final accordingly. The FAA does not consider that this extension will adversely affect safety.
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
There are approximately 29 Dornier Model 328-100 series airplanes of U.S. registry that will be affected by this AD.
The actions that are currently required by AD 94-21-02 take approximately 3 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the previously required actions on U.S. operators is estimated to be $5,220, or $180 per airplane.
The new actions that are required by this new AD will take approximately 120 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operator. Based on these figures, the cost impact of the new requirements of this AD on U.S. operators is estimated to be $208,800, or $7,200 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.
Regulatory Impact
The 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 warrantthe 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 removing amendment 39-9043 (59 FR 51361, October 11, 1994), and by adding a new airworthiness directive (AD), amendment 39-10432, to read as follows: