AD 98-17-08 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to all Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes, that requires repetitive inspections to detect any discrepancy in the sealwire of the fireguards of the engine fire shut-off system, and repair, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent inadvertent closure of the fire shut-off valves due to ineffective or absent sealwires, which could result in in-flight engine shutdown.

Final rule

98-17-08 FOKKER AIRCRAFT B.V.: Amendment 39-10710; Docket 97-NM-287-AD.

Applicability: Model F.28 Mark 1000, F.28 Mark 2000, F.28 Mark 3000, and F.28 Mark 4000 series airplanes; all serial numbers; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent inadvertent closure of the fire shut-off valves due to ineffective or absent sealwires, which could result in in-flight engine shutdown, accomplish the following:

(a) Within 30 days after the effective date of this AD, perform an inspection of the engine fire shut-off system to detect any discrepancy in the sealwire of the fireguards, in accordance with Part I of the Accomplishment Instructions of Fokker Service Bulletin F28/76-20, dated January 1, 1979. If any discrepancy is detected, prior to further flight, repair it in accordance with the service bulletin. Thereafter, repeat the inspection at intervals not to exceed 3,000 flight hours.

(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate. Operators shall submit their request throughan appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(d) The actions shall be done in accordance with Fokker Service Bulletin F28/76-20, dated January 1, 1979. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Fokker Services B.V., Technical Support Department, P.O. Box 75047, 1117 ZN Schiphol Airport, the Netherlands. Copies may be inspected at the FAA, TransportAirplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in Dutch airworthiness directive BLA No. 1979-007/2 (A), dated February 28, 1997.

(e) This amendment becomes effective on September 18, 1998.

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 Fokker Model F.28 Mark 1000, 2000, 3000, and 4000 series airplanes was published in the Federal Register on December 1, 1997 (62 FR 63473). That action proposed to require repetitive inspections to detect any discrepancy in the sealwire of the fireguards of the engine fire shut-off system, 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.

One commenter supports the proposed rule.

Request for Clarification of Required Actions
One commenter requests clarification as to whether the intent of the proposed AD is to require a check of the switch rigging even if the sealwire is found to be in place, or whether verification of the existence of the sealwire is sufficient for compliance with the AD. The commenter suggests that if only the latter action is required, the proposed AD could be clarified in this regard by specifying accomplishment of the inspection in paragraph (a) of the AD in accordance with Part I only of Fokker Service Bulletin F28/76-20, dated January 1, 1979. The FAA concurs with the commenter's request to clarify the actions required by the AD. The intent of the AD is to require the inspections in accordance with Part I only of the referenced service bulletin. Paragraph (a) of the final rule has been revised accordingly.

Request for Revision of Compliance Intervals
One commenter states that accomplishment of the inspections at compliance intervals of 3,000 flight hours is not effective, since 3,000 flight hours for this operator is approximately 18 months. The commenter suggests that selection of an appropriate inspection interval should be left to each operator, to be justified with its Principal Maintenance Inspectorin accordance with its maintenance program. The commenter further suggests that the proposed AD could instead require the inspection to be performed at a regularly scheduled maintenance interval, such as an "A" check.

The FAA does not concur. The FAA normally selects compliance times to coincide with operators' normal maintenance schedules, whenever the unsafe condition is not so urgent that a shorter compliance time is necessary. However, the FAA does not consider it appropriate to base compliance times on indefinite or nonspecific intervals such as "at the next A check." Since maintenance schedules vary from operator to operator, there can be no assurance that the action would be accomplished within the timeframe for safe operation of the aircraft.

In developing an appropriate compliance interval for the inspections required by this AD, the FAA considered the safety implications and operators' normal maintenance schedules for accomplishment of the repetitive inspections of the fireguard sealwire. In consideration of these factors, the FAA finds that the compliance time, as proposed, represents an appropriate and definitive interval in which the required inspections can be accomplished within the fleet and still maintain an adequate level of 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 change described previously. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact
The FAA estimates that 49 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required inspection, 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 $2,940, or$60 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:

The service information referenced in this AD may be obtained from Fokker Services B.V., Technical Support Department, P.O. Box 75047, 1117 ZN Schiphol Airport, the Netherlands. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.