Airworthiness Directives; Boeing Model 737-100, -200, and -200C Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule; request for comments.

SUMMARY:

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-100, -200, and -200C series airplanes. This action requires repetitive inspections to detect discrepancies in the upper and lower skins of the fuselage lap joint, and repair, if necessary. This action is necessary to detect and correct such discrepancies, which could result in sudden fracture and failure of a lap joint and rapid decompression of the airplane fuselage.

DATES:

Effective September 11, 2000.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of September 11, 2000.

Comments for inclusion in the Rules Docket must be received on or before October 24, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-288-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-iarcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-288-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in this AD may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. 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.

FOR FURTHER INFORMATION CONTACT:

Scott Fung, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1221; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

The FAA has received a report indicating in-flight rapid decompression of a Boeing Model 737 series airplane. Investigation revealed that the skin above the forward entry door was separated at the stringer S-4R lap joint, with a 28-inch tear running along the lap joint. The skin was bent back at the upper edge of the stringer at S-5R and formed a rectangular opening that progressed from body station (BS) 328 to BS 300. Further investigation revealed that numerous scratches on the skin of the lap joint had initiated fatigue cracks and subsequent tearing of the skin. Fatigue cracking and corrosion in other lap joints were also detected at various locations on the airplane. The airplane had accumulated 78,198 flight cycles and 77,115 flight hours. The FAA also has received reports of similar damage (corrosion and cracking) to certain lap joints on other Model 737 series airplanes. Such discrepancies, if not corrected, could result in sudden fracture and failure of a lap joint and rapid decompression of the airplane fuselage.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin 737-53A1224, dated August 17, 2000, which describes procedures for inspections (initial and repetitive eddy current and detailed visual) to detect discrepancies (i.e., cracks, pillowing, corrosion, delamination, or loose or missing fasteners) in the upper and lower skins of the fuselage lap joint, and repair of any discrepancies.

Explanation of the Requirements of the Rule

Since an unsafe condition has been identified that is likely to exist or develop on other Boeing Model 737 series airplanes of the same type design, this AD is being issued to detect discrepancies in the upper and lower skins of the fuselage lap joint. This AD requires repetitive inspections to detect discrepancies of the upper and lower skins of the fuselage lap joint, and repair, if necessary. The actions are required to be accomplished in accordance with the alert service bulletin described previously, except as discussed below.

Difference Between Alert Service Bulletin and This AD

Operators should note that, although the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this AD requires the repair of those conditions to be accomplished in accordance with a method approved by the FAA, or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings.

Interim Action

This is considered to be interim action. The manufacturer has advised that it currently is considering developing a modification that will positively address the unsafe condition addressed by this AD. Should this modification be developed, approved, and available, the FAA may consider additional 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.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the AD is being requested.
• Include justification (e.g., reasons or data) for each request.

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 2000-NM-288-AD.” The postcard will be date stamped and returned to the commenter.

Regulatory Impact

The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.

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.

2. Section 39.13 is amended by adding the following new airworthiness directive:

2000-17-04 Boeing: Amendment 39-11878. Docket 2000-NM-288-AD.

Applicability: Model 737-100, -200, and -200C series airplanes, line numbers 1 through 291 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, unless accomplished previously.

To detect and correct discrepancies in the upper and lower skins of the fuselage lap joint, which could result in sudden fracture and failure of a lap joint and rapid decompression of the airplane fuselage, accomplish the following:

Initial and Repetitive Inspections

(a) Perform the applicable (initial and repetitive) inspections as specified in Figures 1 through 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1224, dated August 17, 2000, to detect discrepancies (i.e., cracks, pillowing, corrosion, delamination, or loose or missing fasteners) in the upper and lower skins of the fuselage lap joint. Perform the inspections at the applicable times specified in Tables 1 and 2 of Section 1.E. “Compliance” of the alert service bulletin, in accordance with the alert service bulletin; except that where Table 1 specifies a compliance time of “airplane flight cycles at time of service bulletin release,” this AD requires a compliance time of “airplane flight cycles as of the effective date of this AD.”

Repair

(b) Prior to further flight, repair any discrepancies detected during any inspection required by this AD in accordance with Boeing Alert Service Bulletin 737-53A1224, dated August 17, 2000. If any discrepancies are detected and the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repairs, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings.

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, Seattle ACO, FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with §§ 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) of this AD, the inspections and repair shall be done in accordance with Boeing Alert Service Bulletin 737-53A1224, dated August 17, 2000. 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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. 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.

Effective Date

(f) This amendment becomes effective on September 11, 2000.