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 all Dornier Model 328-100 series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on February 26, 1999 (64 FR 9453). That action proposed to require repetitive inspections for chafing of various control cables, and replacement of any chafed cable with a serviceable cable. That action also proposed to expand the areas to be inspected to detect damage and discrepancies, and provide for corrective action, if necessary; add a requirement for repetitive inspections of certain fairleads/swivel guides to detect damage and other discrepancies, and corrective action, if necessary; and extend the compliance time for the initial inspections.
Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
Request to Extend Inspection Interval
One commenter requests that the proposed AD be revised to require repetitive inspections at intervals of 3,000 flight hours rather than 1,500 flight hours. The commenter states that its inspection results normally reveal cable or cable run wear close to limits, but rarely are any cable strands found to be broken. The commenter states that with these results, and with the conservatism that the manufacturer has incorporated into the maintenance manual, a 3,000-flight-hour interval is justified.
The FAA does not concur. The proposed inspection interval is based on the manufacturer's review of in-service data. The manufacturer has advised the FAA that it is assessing the validity of extending the inspection interval to 3,000 flight hours based on laboratory testing and additional in-service experience, but does not yet recommend such an extension. Based on this information, the FAA has determined that the current inspection interval of 1,500 flight hours is appropriate. No change is made to the AD.
Modifications Available for Extension of Inspection Interval
One commenter, the manufacturer, advises the FAA that certain technical solutions are in place that would allow the inspection interval in the supplemental NPRM to be extended from 1,500 flight hours to 4,000 flight hours. These technical solutions are provided in four service bulletins, described below.
Dornier Service Bulletin SB-328-76-152, which describes procedures for modification of the fairleads in the wing/nacelle firewall.
Dornier Service Bulletin SB-328-76-168, which describes procedures for modification of the mounting brackets of the control cable pulleys in the pulley box.
Dornier Service Bulletin SB-328-27-253, which describes procedures for installation of improved fairleads at frames 15 and 19.
Honeywell Service Bulletin 4005842-22-3, which describes procedures for introduction of improved autopilot servo drums.
The commenter states that incorporation of these service bulletins would allow alignment of the inspection intervals imposed by Dornier Alert Service Bulletin ASB-328-00-011, Revision 1, dated June 5, 1996, to each "C" check interval of 4,000 flight hours, in accordance with Dornier's recently revised Maintenance Review Board (MRB) documents. Dornier Alert Service Bulletin ASB-328-00-011, Revision 1, was cited in this supplemental NPRM as the appropriate source of service information for accomplishing the required actions.
The FAA infers that the commenter is requesting that the AD be revised to allow for an extension of the inspection interval if an operator chooses to accomplish the modifications in the four service bulletins previously described. The FAA does not concur. The commenter did not provide substantiating data to indicate that accomplishment of the modifications constitutes an acceptable method that would allow extension of the inspection interval. Dornier has since advised the FAA that Service Bulletin ASB-328-00-011 is in the process of revision to reference the modifications and provide details of the interval extension. Since the service bulletin revision is not currently available, the FAA does not consider it appropriate to further delay issuance of this final rule while awaiting information regarding the acceptability of the modifications as a means of extending the inspection intervals. However, once such a method is available and approved, operators may request approval of an alternative method of compliance to allow accomplishment of the modifications as a method that would allow extension of the inspection intervals required by this AD.
Request to Include Terminating Action
The same commenter advises the FAA of technical solutions currently under development that would provide terminating action to the requirements of the supplemental NPRM. Three new Dornier Service Bulletins, SB-328-27-290, SB-328-27-291, and SB-328-27-292, when issued, will describe procedures for further improvements to prevent autopilot cable chafing. The commenter requests an additional 60 days to submit the related technical data for consideration to be included in the final rule. Including these actions in the AD would provide a terminating action for operators and would eliminate the need for future AD revisions.
The FAA does not concur. At the time the comment was submitted, the commenter expected that these service bulletins would be issued by June 1999. After further discussions with Dornier, the FAA has been advised that the three new service bulletins have not yet been issued. Due to problems with availability of materials, the estimated date of issuance for the service bulletins is now December 1999. In light of this information, the FAA does not consider it appropriate to further delay issuance of the final rule. Once these service bulletins are available and approved, operators may request approval of an alternative method of compliance to allow accomplishment of the modifications as a terminating action for the repetitive inspection requirements of this AD. No change is made to the final rule.
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 as proposed.
Cost Impact
The FAA estimates that 51 airplanes of U.S. registry will be affected by this AD, that it will take approximately 6 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $18,360, or $360 per airplane, per inspection cycle.
The cost impact figure discussed above is 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 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: