01-22092. 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 all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. For certain airplanes, this proposal would require a one-time inspection or a review of the maintenance records of the airplane to determine if a particular control rod barrel for the aileron tabs is installed, and follow-on repetitive inspections for cracking of the control rod barrels and replacement of the control rod barrels with new barrels, if necessary. Such replacement would terminate the repetitive inspections. For all airplanes, this proposal would prohibit installation of a certain control rod barrel for the aileron tabs. This action is necessary to prevent the disconnection of an aileron tab, which could lead to severe airframe vibrations; consequent damage to the aileron tab, aileron, and wing; and loss of controllability of the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by October 19, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-394-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 [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-394-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:

James Blilie, 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-394-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-394-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report indicating that a control rod barrel for the aileron tabs was found broken in half on a Boeing Model 737-500 series airplane. An examination of the broken control rod barrel revealed incorrect machining of an internal thread relief groove during manufacturing, which resulted in extremely thin walls on the control rod barrel. Investigation has revealed that this condition may exist in an entire lot of parts. This condition, if not corrected, could result in disconnection of an aileron tab, which could lead to severe airframe vibrations; consequent damage to the aileron tab, aileron, and wing; and loss of controllability of the airplane.

Though the broken control rod barrel was found on a Model 737-500 series airplane, the same control rod barrels may be installed on certain other Model 737-100, -200, -200C, -300, and -400 series airplanes.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Special Attention Service Bulletin 737-27-1223, dated October 21, 1999, which describes procedures for a one-time inspection to determine whether the control rod barrels of the aileron tabs are from the affected lot, and follow-on repetitive inspections for cracking of the control rod barrels and replacement of the control rod barrels with new control rod barrels, if necessary. The procedures involve inspecting for a control rod barrel with part number 69-60083-1, which is accomplished by determining the color of the control rod barrels. (Control rod barrels installed on airplanes between line numbers 1 through 3110 inclusive were painted white. Control rod barrels installed on airplanes with line numbers 3111 and subsequent were painted gray.) For white control rod barrels, the service bulletin describes procedures for follow-on repetitive detailed visual inspections for cracking of the control rod barrels, and replacement of the control rod barrels with new control rod barrels. Replacement of white-colored control rod barrels with new control rod barrels eliminates the need for the repetitive inspections. If any cracked control rod barrel is found, all control rod barrels must be replaced at the same time because, as stated above, the discrepancy may exist in the entire lot of parts. The service bulletin specifies that all control rod barrels having part number 69-60083-1 (which are painted white) must eventually be replaced, regardless of whether they are cracked or not. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

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, the proposed AD would require accomplishment of the actions specified in the service bulletin described previously, except as discussed below under the heading “Difference Between Proposed Rule and Service Bulletin.” In lieu of the inspection for control rod barrels with a certain part number by determining the color of the control rod barrels, which is described in the service bulletin, the FAA has determined that a review of the maintenance records of the airplane to determine if a particular part number of control rod barrel is installed is acceptable for compliance with this proposed AD. The proposed AD also would require that operators report findings of discrepant barrels to the Boeing Certification Management Office.

Difference Between Proposed Rule and Service Bulletin

This proposed rule differs from the service bulletin in that it would apply to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. The service bulletin lists only Model 737-100, -200, -200C, -300, -400, and -500 series airplanes having line numbers 1 through 3110 inclusive. The airplane manufacturer delivered airplanes having line numbers 3111 and subsequent with control rod barrels for the aileron tabs having a different part number than the ones subject to this AD. However, the FAA has determined that it is possible that a control rod barrel subject to this AD could be installed after the effective date of this AD on an airplane after line number 3110. Thus, it is necessary to make the requirements of this AD applicable to all Model 737-100, -200, -200C, -300, -400, and -500 series airplanes.

Cost Impact

There are approximately 2,900 airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,250 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 1 work hour per airplane to accomplish the proposed inspection to determine the color of the control rod barrels for the aileron tabs or the proposed review of maintenance records, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this proposed inspection on U.S. operators is estimated to be $75,000, or $60 per airplane.

The cost impact figure discussed above is 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.

If subject control rod barrels are installed, it would take approximately 1 work hour to accomplish the proposed follow-on inspections, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this proposed follow-on inspection is estimated to be $60 per airplane, per inspection cycle.

If subject control rod barrels are installed, it would take approximately 2 work hours to replace each control rod barrel, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this proposed replacement is estimated to be $120 per airplane. Up to four control rod barrels (two for each aileron) may need to be replaced on each airplane.

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-394-AD.

Applicability: All Model 737-100, -200, -200C, -300, -400, and -500 series airplanes; 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 (e) 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 a disconnected aileron tab, which could lead to severe airframe vibrations; consequent damage to the aileron tab, aileron, and wing; and loss of controllability of the airplane; accomplish the following:

One-Time Inspection

(a) Within 3,200 flight hours after the effective date of this AD, do paragraph (a)(1) or (a)(2) of this AD.

(1) Do a one-time general visual inspection to determine whether an aileron tab control rod barrel having part number 69-60083-1 is installed by determining the color of the control rod barrels, according to Boeing Special Attention Service Bulletin 737-27-1223, dated October 21, 1999. No further action is required by this AD for gray-colored control rod barrels. If any white-colored control rod barrel with part number 69-60083-1 is installed, or if the color or part number of any control rod barrel cannot be determined, do paragraph (b) of this AD.

(2) Review the maintenance records for the airplane to determine whether an aileron tab control rod barrel having part number 69-60083-1 is installed. If no control rod barrel with that part number is installed, no further action is required by this AD. If any control rod barrel with that part number is installed, do paragraph (b) of this AD.

Note 2:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Follow-On Actions: Repetitive Inspections and Replacement

(b) For airplanes that have a control rod barrel for the aileron tabs having part number 69-60083-1 or a control rod barrel on which the color or part number cannot be determined: Within 3,200 flight hours after the effective date of this AD, do a detailed visual inspection for cracking of the affected control rod barrels according to Boeing Special Attention Service Bulletin 737-27-1223, dated October 21, 1999.

Note 3:

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.”

(1) If no cracking is found, repeat the inspection for cracking at least every 3,200 flight cycles, AND, within 20,000 flight cycles after the effective date of this AD, replace all affected control rod barrels for the aileron tabs with new or reworked control rod barrels, according to the service bulletin. Such replacement terminates the repetitive inspections.

(2) If any cracking is found, before further flight, replace all control rod barrels with new or reworked control rod barrels, according to the service bulletin.

Note 4:

If any control rod barrel for the aileron tab is cracked, all affected control rod barrels on the airplane must be replaced at the same time because the discrepancy may exist in the entire lot of parts.

Reporting Requirement

(c) If any cracked control rod barrel for the aileron tabs is found during the inspections required by paragraph (b) of this AD, report findings to the FAA Certification Management Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056, at the applicable time specified in paragraph (c)(1) or (c)(2) of this AD. 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.

(1) For airplanes on which the inspection is accomplished after the effective date of this AD: Submit the report within 10 days after performing the inspection required by paragraph (b) of this AD.

(2) For airplanes on which the inspection has been accomplished prior to the effective date of this AD: Submit the report within 10 days after the effective date of this AD.

Spares

(d) For all airplanes: As of the effective date of this AD, no person may install a control rod barrel for the aileron tab having part number 69-60083-1 on any airplane.

Alternative Methods of Compliance

(e) 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 Permits

(f) 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.

Issued in Renton, Washington, on August 27, 2001.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.