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 May 25, 1995 (60 FR 27704). That action proposed to require replacement of the return filter diaphragm assemblies on hydraulic systems 1 and 2 with modified filter units having new diaphragms.
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 Withdraw Proposed AD
The Air Transport Association (ATA) of America, on behalf of one member, requests that the proposed AD be withdrawn because the corrective action specified in the referenced Fokker Service Bulletin SBF100-29-025, dated December 31, 1993, is ineffectual in preventing overpressure of the subject hydraulic return system.
The FAAdoes not concur with the commenter's request to withdraw the proposal. The Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, has advised the FAA that there have been no additional reports of discrepancies in the system since the service bulletin was issued. In addition, the commenter provides no justification to substantiate the claim that the corrective action is ineffectual. Based on this information, the FAA has determined that the modification specified in Fokker Service Bulletin SBF100-29-025, dated December 31, 1993, adequately addresses the unsafe condition.
Request to Extend Compliance Time
One commenter requests an extension of the proposed compliance time of 6 months, but provides no specific extension time. The commenter's request is based on the number of airplanes in its fleet and the time required to accomplish the action. The commenter expresses concern that it may not be able to modify all airplanes in 6 months.
TheFAA does not concur with the request for an extension of the compliance time. In developing the compliance time, the FAA considered the safety implications, parts availability, and normal maintenance schedules. In consideration of all these factors, and the time since the Notice of Proposed Rulemaking (NPRM) was published, the FAA has determined that the compliance time, as proposed, represents an appropriate interval to complete the necessary replacement.
Request to Revise Unsafe Condition
One commenter, the manufacturer, requests that the description of the cause of the addressed unsafe condition that appeared in the proposed AD be clarified. The unsafe condition that appears in the proposal reads as follows: "... to prevent overpressure in the hydraulic return system which could result in reduced braking performance and/or blown tires due to brake overheating." The commenter suggests that a more accurate description would be "... to prevent too high pressure in the hydraulic return system during the selection of the subsystem(s), which could result in inadvertent braking and/or blown tires." The manufacturer states that its service bulletin was issued following an incident in which all four tires blew on touchdown. During a taxi check, following the replacement of several components, inspections revealed a brake problem. It was found that the brakes locked as soon as the flaps moved to a new position and unlocked as soon as the flaps stopped moving.
The FAA concurs. Based on the information provided by the manufacturer following further investigation into the incident, the FAA has revised the unsafe condition in this final rule to reflect the commenter's suggestion.
Request for Inclusion of Operator Modification as Alternative Method of Compliance
One commenter requests that the FAA revise the proposed AD to include its own modification as an acceptable alternative method of compliance for replacing the diaphragms with filter elementretaining spacers. The commenter, in collaboration with Fokker and PALL-APME, has developed a new modification, which it believes satisfactorily addresses the safety objective of the proposed AD. The commenter is of the opinion that if an AD is issued, it should include that modification as an acceptable means of compliance. The commenter also states that the applicability of the proposed AD should not include those aircraft on which units having modified part numbers designated by -1 are installed.
The FAA does not concur that the modification suggested by the commenter should be incorporated in this final rule, or that airplanes on which the modified part numbers designated by "-1" are installed should be excluded from the applicability. The FAA does not consider it appropriate to include various provisions in an AD applicable to a single operator's unique modification. However, paragraph (c) of this AD contains a provision for requesting approval of an alternative method of compliance to address these types of individual circumstances.
Request to Revise Cost Impact Information
One commenter, the manufacturer, requests that the cost impact information, below, be revised to reflect that only 79 airplanes of U.S. registry are affected by the proposed AD. The change is requested based on the most current information available to the manufacturer.
The FAA concurs and has revised the cost impact information, below, accordingly.
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 79 Model F28 Mark 0100 series airplanes of U.S. registry will be affected by this AD, that it will take approximately2 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will be provided by the parts manufacturer at no cost to operators. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $9,480, or $120 per airplane.
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: