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 of the aft end of each inboard flap track of the wing outboard flap, and corrective actions, if necessary. This action is necessary to detect and correct damage of the aft end of each flap track, which could result in loss of the outboard trailing edge flap and consequent loss of controllability of the airplane.

DATES:

Effective January 2, 2001.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of January 2, 2001.

Comments for inclusion in the Rules Docket must be received on or before February 16, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-365-AD, 1601 Lind Avenue, SW, Renton, Washington 98055-4056.

Comments may be inspected at this location between 9 a.m. and 3 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-365-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:

Nenita Odesa, Aerospace Engineer, Airframe Branch, ANM-120S; FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2557; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

The FAA has received a report indicating that cracking of the aft end of an inboard flap track of the wing outboard flap was found on a Model 737-200 series airplane having improved flap tracks installed. The cracking was found during an inspection that was conducted to resolve problems with the trim that occurred during flight. The airplane had accumulated 38,484 flight cycles. The inner and outer webs of the track, as well as the upper and lower flanges, were severed. The only component holding the aft end of the flap track together was the fail-safe bar, which was bolted to the flap track. There was also a small section broken off the upper outboard chord. Further investigation revealed that the cracks were caused by corrosion at the fasteners that attach the fail-safe bar to the inner and outer webs. Such conditions, if not detected and corrected, could result in loss of the outboard trailing edge flap and consequent loss of controllability of the airplane.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing All Operator Message (AOM) M-7200-00-01854, dated July 27, 2000, which describes procedures for a close (detailed) visual inspection to detect damage (corrosion, cracking) of the aft end of the left- and right-hand inboard flap tracks of the wing outboard flap, and corrective actions. The corrective actions consist of, among other things, repair or rework of any damaged flap tracks.

Explanation of the 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, this AD is being issued to detect and correct damage of the aft end of each flap track at the wing buttock line of the inboard flap track of the wing outboard flap, which could result in loss of the outboard trailing edge flap and consequent loss of controllability of the airplane. This AD requires accomplishment of the inspection and corrective actions specified in the service information described previously, except as discussed below.

Differences Between All Operators Message and This AD

Operators should note that the effectivity listing of the AOM specifies all Boeing Model 737-100 and -200 series airplanes. However, this AD is applicable to certain Boeing Model 737-100, -200, and -200C series airplanes on which the flap tracks have certain Boeing part numbers. The subject flap tracks may have been removed from an airplane and re-installed, without being inspected, on another airplane. Therefore, the FAA finds it necessary to revise the applicability of this AD by limiting the repetitive inspections to only certain Boeing Model 737-100, -200, and -200C series airplanes on which certain flap tracks have been installed.

The AOM specifies a one-time close visual inspection of the aft end of the left- and right-hand inboard flap tracks of the wing outboard flap. This AD requires the applicable inspection to be repeated at intervals not to exceed 1,200 flight cycles, regardless of detection of cracking. The FAA has determined that, because of the safety implications and consequences associated with fracture of the aft end of each inboard flap track of the wing outboard flap, repetitive inspections are necessary.

The AOM references only one flap track part number (P/N) 65-46428-25. The FAA has determined that there are other flap tracks with similar configurations at the aft end that have different P/N's, and those flap tracks would be subject to the same unsafe condition.

Additionally, the AOM specifies that the manufacturer may be contacted for disposition of certain repair conditions, however, this AD requires the repair of those conditions to be accomplished per a method approved by the FAA, or per 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 until final action is identified, at which time 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.

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-365-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.