AD 99-21-33

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F.27 Mark 050 series airplanes. This action requires a one-time inspection to detect improper installation of countersunk screws used to attach the access panels to the bottom skin of the center wing; and corrective action, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified in this AD are intended to detect and correct such improper installation, which could result in fatigue cracking of the bottom skin of the center wing and consequent reduced structural integrity of the airplane.

Final rule; request for comments

99-21-33 FOKKER SERVICES B.V.: Amendment 39-11379. Docket 99-NM-225-AD.

Applicability: Model F.27 Mark 050 series airplanes, serial numbers 20103 through 20263 inclusive; 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 (c) 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, unlessaccomplished previously.

To detect and correct improper installation of countersunk screws in the attachment of access panels of the bottom skin of the center wing, which could result in fatigue cracking of the bottom skin of the center wing and consequent reduced structural integrity of the airplane, accomplish the following:

Initial Inspection
(a) Prior to the accumulation of 24,000 total flight cycles, perform a one-time detailed visual inspection to detect improper installation (excessive gap) of the countersunk screws used to attach the access panels to the bottom skin of the center wing, in accordance with the Accomplishment Instructions of Fokker Service Bulletin SBF50-57-015, dated February 28, 1996.

NOTE 2: For the purposes of this AD, a detailed visual inspection is defined as: "An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required."

Inspection and Corrective Action
(b) If any improper installation (excessive gap) is found during the inspection required by paragraph (a) of this AD: Prior to the accumulation of 24,000 total flight cycles, ream the fastener holes in the rabbet of the bottom skin of the center wing and perform an eddy current inspection for cracking of the fastener holes in accordance with the Accomplishment Instructions of Fokker Service Bulletin SBF50-57-018, dated February 28, 1996.

Repair
(1) For any fastener hole for which no crack is found during the eddy current inspection: Prior to further flight; accomplish corrective actions for the fastener hole, in accordance with Step C. of Repair Scheme No. 1 of Fokker Service Bulletin SBF50-57-018, dated February 28, 1996.

(2) For any fastener hole for which a crack is found during the eddy current inspection: Prior to further flight; repair and re-inspect the fastener hole, in accordance with Steps A. and B. of Repair Scheme No. 1 of Fokker Service Bulletin SBF50-57-018, dated February 28, 1996. For any crack that is outside the limits specified in the service bulletin, prior to further flight, repair in accordance with a method approved by either the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate; or the Rijksluchtvaartdienst (RLD) (or its delegated agent). For a repair method to be approved by the Manager, International Branch, ANM-116, as required by this paragraph, the Manager's approval letter must specifically reference this AD.

Alternative Methods of Compliance
(c) 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 requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

Special Flight Permits
(d) 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.

Incorporation by Reference
(e) Except as provided by paragraph (b)(2) of this AD, the actions shall be done in accordance with Fokker Service Bulletin SBF50-57-015, dated February 28, 1996, and Fokker Service Bulletin SBF50-57-018, dated February 28, 1996. 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., P.O. Box 231, 2150 AE Nieuw-Vennep, The Netherlands. Copies may be inspected at the FAA, Transport Airplane 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 4: The subject of this AD is addressed in Dutch airworthiness directive 1996-042 (A), dated April 29, 1996.

(f) This amendment becomes effective on November 4, 1999.

The Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, notified the FAA that an unsafe condition may exist on certain Fokker Model F.27 Mark 050 series airplanes. The RLD advises that, on a number of airplanes on the production line, the heads of countersunk screws were found not to seat properly in their countersinkings. The affected screws are used in the attachment of access panels of the bottom skin of the center wing. This condition, if not corrected, could result in fatigue cracking of the bottom skin of the center wing and consequent reduced structural integrity of the airplane.

Explanation of Relevant Service Information
Fokker has issued Service Bulletin SBF50-57-015, dated February 28, 1996, which describes procedures for a one-time detailed visual inspection to detect improper installation (excessive gap) of the countersunk screws in the access covers of the bottom skin of the center wing.

Fokker has also issued Service Bulletin SBF50-57-018, dated February 28, 1996, which describes procedures for reaming of the fastener holes and an eddy current inspection to detect cracks in the bottom skin of the center wing. This service bulletin also describes procedures to repair any cracking that is found.

The RLD classified these service bulletins as mandatory and issued Dutch airworthiness directive 1996-042 (A), dated April 29, 1996, in order to assure the continued airworthiness of these airplanes in the Netherlands.

FAA's Conclusions
This airplane model is manufactured in the Netherlands and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.19) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the RLD has kept the FAA informed of the situation described above. The FAA has examined the findings of the RLD, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of Requirements of the Rule
Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD is being issued to detect and correct improper installation of countersunk screws in the attachment of access panels of the bottom skin of the center wing, which could result in fatigue cracking of the bottom skin and consequent reduced structural integrity of the airplane. This AD requires accomplishment of the actions specified in the service bulletins described previously.

Differences Between Rule and Service Bulletin
Operators should note that, although Fokker Service Bulletin SBF50-57-018 specifies that the manufacturer may be contacted for disposition of certain repair conditions, this AD would require the repairof those conditions to be accomplished in accordance with a method approved by the FAA.

Cost Impact
None of the airplanes affected by this action are on the U.S. Register. All airplanes included in the applicability of this rule currently are operated by non-U.S. operators under foreign registry; therefore, they are not directly affected by this AD action. However, the FAA considers that this rule is necessary to ensure that the unsafe condition is addressed in the event that any of these subject airplanes are imported and placed on the U.S. Register in the future.

Should an affected airplane be imported and placed on the U.S. Register in the future, it would require approximately 6 work hours to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this AD would be $360 per airplane.

Determination of Rule's Effective Date
Since this AD action does not affect any airplane that is currently onthe U.S. register, it has no adverse economic impact and imposes no additional burden on any person. Therefore, prior notice and public procedures hereon are unnecessary and the amendment may be made effective in less than 30 days after publication in the Federal Register.

Comments Invited
Although this action is in the form of a final rule and was not preceded by notice and opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 99-NM-225-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the nationalgovernment 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: