01-13582. Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This proposal would require initial and repetitive inspections of the elevator tab assembly to find any damage or discrepancy; and corrective actions, if necessary. This action is necessary to prevent excessive in-flight vibrations of the elevator tab, which could lead to loss of the elevator tab and consequent loss of controllability of the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by July 16, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-44-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 [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-44-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 the proposed rule 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.

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 [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

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 proposed 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 proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-44-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-44-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received several reports indicating high-frequency airframe vibrations of the elevator tab on certain Boeing Model 737 series airplanes during flight. Such vibrations have been attributed to excessive free-play of the elevator tab, resulting in severe damage to the elevator, elevator tab, and elevator tab control mechanism. Several reports indicated that the source of the vibration was an elevator tab vibrating due to wear of the hinges and the control system, which caused the elevator tab assemblies to come loose. Another report indicated incorrect installation of the elevator tab assembly and tab control mechanism due to improper maintenance. In one incident, a portion of the elevator tab separated from the airplane causing damage to the elevator tab, elevator, and horizontal stabilizer. In another incident there was severe damage to the airplane's elevator and elevator tab assembly. Several incidents resulted in severe structural damage to the elevator tab assembly. These conditions, if not corrected, could result in loss of the elevator tab and consequent loss of controllability of the airplane.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 737-55A1070, Revision 1, dated May 10, 2001, including Appendices A, B, and C. The inspection procedures specified in this service bulletin are listed in the table, below:

Inspection Procedures

Work package and action specified	Figure
I—Initial detailed visual/free play inspections of the following:
• Attachment of the elevator tab assembly at four hinge locations	3, 4
• Elevator tab trailing edge	3, 4
• Elevator tab axial	3, 4
• Elevator tab control mechanism to the horizontal stabilizer, elevator front spar, and elevator tab push rods	5-7
• Elevator tab push rods to the elevator tab mast fitting/tab rod adjustment lock nut	5-7
• Elevator tab assembly installation	8-11
Note: The service bulletin recommends scheduling the repetitive inspections to coincide with the inspections specified in Work Packages II and III.
II—Repetitive free-play inspections of the following:
• Elevator tab hinges 1 through 4	3, 4
• Elevator tab trailing edge	3, 4
• Elevator tab axial	3, 4
III—Repetitive free-play inspections of the following:
• Elevator tab hinges 1 through 4	3, 4
• Elevator tab trailing edge	3, 4
• Elevator tab axial	3, 4

In addition, the service bulletin specifies corrective actions that include, among other things, repairing, replacing, reworking; and aligning and torqueing certain components. Procedures also specify the replacement of any damaged or discrepant part with a new part, or repair, as applicable. Discrepancies include loose or missing parts or excessive wear.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, this proposed AD is being issued to prevent excessive in-flight airframe vibrations of the elevator tab, which could lead to loss of the elevator tab and consequent loss of controllability of the airplane. This proposed AD requires initial and repetitive inspections of the elevator tab assembly to find any damage or discrepancy; and corrective actions, if necessary. The proposed AD would require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.

Difference Between the Service Bulletin and This Proposed AD

Although the service bulletin uses the term “check” for certain inspections, this AD uses the term “inspection.”

Interim Action

This is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.

Cost Impact

There are approximately 2,790 Model 737 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,080 airplanes of U.S. registry would be affected by this proposed AD.

Work package	Work hours @ $60/WH	Cost per airplane	Fleet cost
I	18	$1,080	$1,166,400
II	9	540	583,200
III	14	840	907,200

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein would 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 proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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:

Boeing: Docket 2000-NM-44-AD.

Applicability: Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, line numbers 1 through 3132 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 per paragraph (d) 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 excessive in-flight vibrations of the elevator tab, which could lead to loss of the elevator tab and consequent loss of controllability of the airplane, accomplish the following:

Initial/Repetitive Inspections

(a) Do the applicable initial detailed visual/free play inspections of the elevator tab assembly on the left and right sides of the airplane to find any damage or discrepancy per Work Package I of Boeing Service Bulletin 737-55A1070, Revision 1, dated May 10, 2001; at the times specified in paragraph (a)(1) or (a)(2) of this AD, as applicable. Repeat the free-play inspections after that at intervals not to exceed 1,500 flight cycles or 2,000 flight hours, whichever comes first, per either Work Package II or Work Package III of the service bulletin.

Note 2:

There is a one-way interchangeability between the free-play inspections specified in Work Packages II and III. The repetitive free-play inspections specified in Work Package II can be replaced by the repetitive free-play inspections specified in Work Package III. But the repetitive free-play inspections specified in Work Package III cannot be replaced by the repetitive free-play inspections specified in Work Package II.

(1) For airplanes having less than 4,500 total flight cycles: Before the accumulation of 4,500 total flight cycles or within 120 days after the effective date of this AD, whichever comes later.

(2) For airplanes having 4,500 or more total flight cycles: Do the inspections at the times specified in paragraph (a)(2)(i) or (a)(2)(ii), as applicable.

(i) Within 120 days after the effective date of this AD.

(ii) If the initial inspections were done before the effective date of this AD per Boeing All Operator Telex M-7200-00-00034, dated February 15, 2000: Within 1,500 flight cycles or 2,000 flight hours after the effective date of this AD, whichever comes later.

Note 3:

Initial inspections done before the effective date of this AD per Boeing Alert Service Bulletin 737-55A1070, dated January 13, 2000, are considered acceptable for compliance with the initial inspections required by paragraph (a) of this AD.

Note 4:

For the purposes of this AD, a detailed inspection is defined as: “An intensive visual examination of a specific structural area, system, installation or assembly to find 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.”

(b) Within 4,500 flight cycles or 6,000 flight hours, whichever comes first, after doing the initial inspections required by paragraph (a) of this AD: Do the free-play inspections of the elevator tab assembly on the left and right sides of the airplane to find any damage or discrepancy per Work Package III of Boeing Service Bulletin 737-55A1070, Revision 1, dated May 10, 2001. Repeat the inspections after that at intervals not to exceed 4,500 flight cycles or 6,000 flight hours, whichever comes first.

Corrective Actions

(c) If any damage or discrepancy is found after doing any inspection required by paragraphs (a) and (b) of this AD, before further flight, do the applicable corrective action per the Accomplishment Instructions of Boeing Service Bulletin 737-55A1070, Revision 1, dated May 10, 2001.

Alternative Methods of Compliance

(d) 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 Aircraft Certification Office (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 5:

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

Special Flight Permit

(e) Special flight permits may be issued per §§ 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.

Issued in Renton, Washington, on May 23, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.