AD 96-19-04 ACTIVE

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Fokker Model F28 Mark 1000, 2000, 3000, and 4000 series airplanes. This action requires a one-time inspection to detect cracks of the dimpled lap joints in the fuselage skin, and repair of cracked lap joints. This amendment is prompted by a report indicating that cracks were found at various locations in the outer skin of the dimpled longitudinal lap joints of the fuselage skin. The actions specified in this AD are intended to prevent such cracking, which could result in reduced structural integrity of the fuselage and/or rapid decompression of the airplane.

Final rule; request for comments

96-19-04 FOKKER: Amendment 39-9752. Docket 96-NM-224-AD.
Applicability: Model F28 Mark 1000, 2000, 3000, and 4000 series airplanes, serial numbers 11017 through 11241 inclusive; on which Fokker Service Bulletin F28/53-121, Revision 1, dated December 13, 1991, has not been accomplished; 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, therequest should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent cracking of the fuselage skin, which could result in reduced structural integrity of the fuselage and/or rapid decompression of the airplane, accomplish the following:

(a) Within 60 days after the effective date of this AD, perform a one-time low frequency eddy current inspection to detect cracks of the dimpled lap joints in the fuselage skin between stringers 16 and 17, stringers 58 and 59, and frames 13345 and 14285, in accordance with Fokker Service Bulletin F28/53-144, dated July 15, 1996.

(1) If no crack is detected, no further action is required by this paragraph.

(2) If any crack is detected, prior to further flight, repair the affected lap joint in accordance with Fokker Service Bulletin F28/53-121, Revision 1, dated December 13, 1991. Accomplishment of the repair is considered acceptable for compliance with AD 92-19-02, amendment 39-8359 (57 FR 40311, September 3, 1992), and constitutes terminating action for the inspection identified as item 53-30-08 of the Fokker structural integrity program, which is required by AD 93-13-04, amendment 39-8617 (58 FR 38513, July 17, 1993).

(b) Within 10 days after accomplishing the inspection required by paragraph (a) of this AD, submit a report of the inspection results (both positive and negative findings) to Fokker Services, ATTN: Manager Service Engineering Jet Aircraft, P.O. Box 75047, 1117 ZN, Schiphol, The Netherlands. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

(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, Standardization Branch, ANM-113, 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, Standardization Branch, ANM-113.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(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.

(e) The inspection shall be done in accordance with Fokker Service Bulletin F28/53-144, dated July 15, 1996. The replacement shall be done in accordance with Fokker Service Bulletin F28/53-121, Revision 1, dated December 13, 1991. The incorporation by reference of Fokker Service Bulletin F28/53-144, dated July 15, 1996, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. The incorporation by reference of Fokker Service Bulletin F28/53-121, Revision 1, dated July 15, 1996, was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of October 8, 1992 (57 FR 40311, September 3, 1992). Copies may be obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street, Alexandria, Virginia 22314. 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.

(f) This amendment becomes effective on September 26,1996.

The Rijksluchtvaartdienst (RLD), which is the airworthiness authority for the Netherlands, recently notified the FAA that an unsafe condition may exist on certain Fokker Model F28 Mark 1000, 2000, 3000, and 4000 series airplanes. The RLD advises that it recently received a report indicating that, during a walk-around inspection of a Model F28 Mark 4000 series airplane, two cracks were found in the outer skin of the left- and right-hand dimpled longitudinal lap joints of the fuselage skin between stations 15263 and 15733, stringers 16 and 17, and stringers 58 and 59. These cracks were approximately 20 inches long. The exact cause of such cracking is unknown at this time.

Currently, AD 93-13-04, amendment 39-8617 (58 FR 38513, July 19, 1993) requires inspection of these airplanes in the area where the recent cracking was found. The inspection is required to be accomplished in accordance with Item 53-30-08 of the Fokker Structural Integrity Program (SIP) Document 28438. AD 93-13-04 requires that the inspection be accomplished by the time that the airplane has accumulated 32,000 total flight cycles, and that it be repeated thereafter at intervals not to exceed 2,700 flight cycles. However, the subject cracking was found on the affected airplane some 3,520 flight cycles before the airplane had reached inspection threshold of 32,000 flight cycles.

In addition, AD 92-19-02, amendment 39-8359 (57 FR 40311, September 3, 1992), requires modification of the subject area in accordance with Fokker Service Bulletin F28/53-121, prior to the accumulation of 32,000 flight cycles. However, the affected airplane had accumulated only 28,480 total flight cycles; therefore, it had not been modified in accordance with that AD at the time cracking was detected.

Cracking in the outer skin of the left- and right-hand dimpled longitudinal lap joints of the fuselage skin between stations 15263 and 15733, stringers 16 and 17, and stringers 58 and59, if not corrected, could result in reduced structural integrity of this area of the fuselage and/or rapid decompression of the airplane.

The configuration of the subject area on Fokker Model Mark 1000, 2000, and 3000 series airplanes is identical to that on the affected Model Mark 4000 series airplane. Therefore, all of these models may be subject to this same unsafe condition.

Explanation of Relevant Service Information
Fokker has issued Service Bulletin F28/53-144, dated July 15, 1996. This service bulletin describes procedures for a one-time low frequency eddy current inspection to detect cracks of the dimpled lap joints in the fuselage skin between stringers 16 and 17, stringers 58 and 59, and frames 13345 and 14285. It also describes procedures for submitting a report of the inspection results to Fokker.

Fokker also has issued Service Bulletin F28/53-121, Revision 1, dated December 13, 1991, which describes procedures for repair of cracked dimpled lap joints. The repair consists of cutting out the lap joint and installing a repair plate and shim on the outside of the fuselage. The repair will minimize the possibility of cracks developing in the subject area of the fuselage.

The RLD classified these service bulletins as mandatory and issued Dutch airworthiness directive BLA 1996-081 (A), dated July 24, 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 21.29) 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 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 prevent cracking in the subject area of the fuselage skin, which could result in reduced structural integrity of the fuselage and/or rapid decompression of the airplane. This AD requires a one-time low frequency eddy current inspection to detect cracks of the dimpled lap joints in the fuselage skin between stringers 16 and 17, stringers 58 and 59, and frames 13345 and 14285; and repair, if necessary. After accomplishing the inspection, the AD also requires operators to submit a report of the inspection results to Fokker. The actions are required to be accomplished in accordance with the service bulletins described previously.

Interim Action
This is considered to be interim action. The inspectionreports that are required by this AD will enable the manufacturer to obtain better insight into the nature, cause, and extent of cracking; and eventually to determine if additional corrective action is necessary to address the unsafe condition. Once final action has been identified, the FAA may consider further rulemaking.

Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an 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 96-NM-224-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 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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 96-NM-224-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
The service information referenced in this AD may be obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street, Alexandria, Virginia 22314. This information may be examined 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.

Tim Dulin, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2141; fax (206) 227-1149.