AD 97-01-10

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AD Number:
97-01-10
Document Type:
AD Final Rules
Docket Number:
96-NM-145-AD
Subject Heading:
Airworthiness Directives; Boeing Model 737-100 and -200 Series Airplanes
Subject:
Aileron Control Transfer Mechanism
Status:
Current
Citation:
(Federal Register: January 15, 1997 (Volume 62, Number 10))
Citation Publish Date:
01/15/1997
Effective Date:
02/19/1997
Make:
The Boeing Company
Model:
737-100 Series | 737-200 Series
Product Type:
Aircraft
Product Subtype:
Large Airplane
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39 (62 FR 2007 NO. 10 01/15/97)
Comments:
Updated RGL applicability to match AD applicability; CAR C-11-185
AIRWORTHINESS DIRECTIVES FINAL RULES: 97-01-10
CITATION:   [Federal Register: January 15, 1997 (Volume 62, Number 10)]

PAGE NUMBER:   [Page 2007]

DOCKET NUMBER:   96-NM-145-AD

AMENDMENT:   39-9881

AD NUMBER:   97-01-10

SUBJECT HEADING:   Airworthiness Directives; Boeing Model 737-100 and -200 Series Airplanes

ACTION:   Final rule

SUMMARY:  
This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737-100 and -200 series airplanes, that requires replacing the aileron (lateral) control transfer mechanism with a new modified mechanism, or reworking the existing mechanism. This amendment is prompted by a review of the design of the flight control systems on Model 737 series airplanes. The actions specified by this AD are intended to prevent unexpected, significant control wheel forces and reduced travel of a control wheel due to mechanical interference within the lateral control system transfer mechanism during a jam override condition.

DATES:   Effective February 19, 1997. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of February 19, 1997.

ADDRESSES:  
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 Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 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:  
Don Kurle, Senior Engineer, Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2798; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION:  
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Boeing Model 737-100 and -200 series airplanes was published in the Federal Register on August 28, 1996 (61 FR 44230). That action proposed to require replacing the aileron (lateral) control transfer mechanism with a new modified mechanism, or reworking the existing mechanism.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Support for the Proposal

Two commenters support the proposed rule.

Request for Risk Benefit Analysis

One commenter believes that the FAA should perform a risk benefit analysis before proceeding with the proposed AD. This commenter does not disagree with the requirements of the proposal; however, the commenter suggests that the proposed compliance time of 18 months could overburden competent machine facilities and lead to undesirable workmanship, which would subject the airlines and the flying public to unnecessary risk.

The FAA does not concur with the commenter's request. The commenter did not submit analyses or data to substantiate its claim that competent machine facilities would be overburdened by the requirements of this AD. The FAA has considered the costs of complying with this AD, and does not consider those costs to be excessive to correct the unsafe condition.

Request to Revise Statement of Findings of Critical Design Review Team

One commenter requests the second paragraph of the Discussion section that appeared in the preamble to the proposed rule be revised to accurately reflect the findings of the Critical Design Review (CDR) team. The commenter asks that the FAA delete the one sentence in that paragraph, which read: "The recommendations of the team include various changes to the design of the flight control systems of these airplanes, as well as correction of certain design deficiencies." The commenter suggests that the following sentences should be added: "The team did not find any design issues that could lead to a definite cause of the accidents that gave rise to this effort. The recommendations of the team include various changes to the design of the flight control systems of these airplanes, as well as incorporation of certain design improvements in order to enhance its already acceptable level of safety."

The FAA does not find that a revision to this final rule in the manner suggested by the commenter is necessary, since the Discussion section of a proposed rule does not reappear in a final rule. The FAA acknowledges that the CDR team did not find any design issue that could lead to a definite cause of the accidents that gave rise to this effort. However, as a result of having conducted the CDR of the flight control systems on Boeing Model 737 series airplanes, the team indicated that there are a number of recommendations that should be addressed by the FAA as may be appropriate to any particular (or all) model(s) of the Model 737.

Request to Revise Service Bulletin Citation

One commenter requests that the FAA change the service bulletin citation from "Boeing Service Bulletin 27-1033" to "Boeing Service Bulletin 737-27-1033." The commenter considers this to be clearer.

The FAA acknowledges that some clarification is necessary. The title that actually appears on the service bulletin document itself is "Boeing Service Bulletin 27-1033;" therefore, the FAA disagrees with the commenter's specific suggestion. However, to avoid any confusion on the part of operators, the FAA has revised the final rule to refer to the service bulletin as "Boeing 737 Service Bulletin 27-1033."

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact

There are approximately 236 Model 737-100 and -200 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 157 airplanes of U.S. registry will be affected by this AD.

For operators that elect to accomplish the replacement, it will take approximately 20 work hours per airplane to accomplish it, at an average labor rate of $60 per work hour. Required parts will cost approximately $15,343 per airplane. Based on these figures, the cost impact of the replacement on U.S. operators is estimated to be $16,543 per airplane.

For operators that elect to accomplish the rework by using new components, it will take approximately 40 work hours to accomplish it, at an average labor rate of $60 per work hour. Required parts will cost approximately $6,500. Based on these figures, the cost impact of the rework (by using new components) on U.S. operators is estimated to be $8,900 per airplane.

For operators that elect to accomplish the rework by machine shop rework of the components, it will take approximately 70 work hours to accomplish it, at an average labor rate of $60 per work hour. Required parts will cost approximately $1,450. Based on these figures, the cost impact of the rework (by machine shop rework of the components) on U.S. operators is estimated to be $5,650 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

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.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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:

REGULATORY TEXT:  
97-01-10 BOEING: Amendment 39-9881. Docket 96-NM-145-AD.

Applicability: Model 737-100 and -200 series airplanes; as listed in Boeing 737 Service Bulletin 27-1033, dated February 13, 1970; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 prevent an unexpected, significant control upset due to mechanical interference within the lateral control system transfer mechanism, which could result in reduced travel of a control wheel and above normal control wheel forces during a jam override, accomplish the following:

(a) Within 18 months after the effective date of this AD: Accomplish the requirements of either paragraph (a)(1) or (a)(2) of this AD, in accordance with Boeing 737 Service Bulletin 27-1033, dated February 13, 1970.

(1) Replace the aileron control transfer mechanism, part number (P/N) 65-54200-4 or -5, with a new modified mechanism in accordance with Procedure I of the Accomplishment Instructions of the service bulletin. Or

(2) Rework the existing aileron control transfer mechanism, P/N 65-54200-4 or -5, in accordance with Procedure II of the Accomplishment Instructions of the service bulletin.

(b) As of the effective date of this AD, no person shall install an aileron control transfer mechanism having P/N 65-54200-4 or -5 unless it has been reworked in accordance with the requirements of paragraph (a)(2) of this AD.

(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 Aircraft Certification Office (ACO), 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, 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.

(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 replacement and rework shall be done in accordance with Boeing 737 Service Bulletin 27-1033, dated February 13, 1970. 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.

(f) This amendment becomes effective on February 19, 1997.

FOOTER: