E8-4674. Airworthiness Directives; Boeing Model 737-200 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule.

SUMMARY:

We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-200 series airplanes. This AD requires repetitive inspections to detect cracking of the support fittings of the Krueger flap actuators, and corrective actions if necessary. This AD also requires eventual replacement of any existing aluminum support fitting on each wing with a steel fitting, and modification of the aft attachment of the actuator. Doing these actions terminates the repetitive inspection requirements. This AD results from reports of cracking due to fatigue and stress corrosion of the support fittings of the Krueger flap actuator. We are issuing this AD to prevent cracking of the support fittings, which could result in fracturing of the actuator attach lugs, separation of the actuator from the support fitting, severing of the hydraulic lines, resultant loss of hydraulic fluids, and consequent reduced controllability of the airplane.

DATES:

This AD is effective April 16, 2008.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of April 16, 2008.

ADDRESSES:

For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The address for the Docket Office (telephone [phone]) is the Document Management Facility, U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT:

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to certain Boeing Model 737-200 series airplanes. That NPRM was published in the Federal Register on November 26, 2007 (72 FR 65909). That NPRM proposed to require repetitive inspections to detect cracking of the support fittings of the Krueger flap actuators, and corrective actions if necessary. The NPRM also proposed to require eventual replacement of any existing aluminum support fitting on each wing with a steel fitting, and modification of the aft attachment of the actuator. Doing these actions terminates the repetitive inspection requirements.

Comments

We gave the public the opportunity to participate in developing this AD. We considered the one comment received. Boeing supports the NPRM.

Conclusion

We reviewed the relevant data, considered the comment received, and determined that air safety and the public interest require adopting the AD as proposed.

Costs of Compliance

There are about 13 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Inspection	5	$80	$0	$400, per inspection cycle	3	$1,200, per inspection cycle.
Replacement	88	80	29,642	$36,682	3	$110,046.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. “Subtitle VII: Aviation Programs,” describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in “Subtitle VII, Part A, Subpart III, Section 44701: General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

This AD will not have federalism implications under Executive Order 13132. This AD 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.

For the reasons discussed above, I certify that this AD:

(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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by Reference
• Safety

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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. The FAA amends § 39.13 by adding the following new AD:

2008-06-09 Boeing: Amendment 39-15421. Docket No. FAA-2007-0228; Directorate Identifier 2007-NM-107-AD.

Effective Date

(a) This airworthiness directive (AD) is effective April 16, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 737-200 series airplanes, line numbers 814 through 826 inclusive, certificated in any category.

Unsafe Condition

(d) This AD results from reports of cracking due to fatigue and stress corrosion of the support fittings of the Krueger flap actuator. We are issuing this AD to prevent cracking of the support fittings, which could result in fracturing of the actuator attach lugs, separation of the actuator from the support fitting, severing of the hydraulic lines, resultant loss of hydraulic fluids, and consequent reduced controllability of the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Repetitive Inspections

(f) Within 12 months after the effective date of this AD, do a high frequency eddy current (HFEC) inspection to detect cracking of the support fittings of the Krueger flap actuator on each wing, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-57-1129, Revision 3, dated March 19, 2007.

(1) If no cracking is detected, repeat the inspection thereafter at intervals not to exceed 3,000 flight hours until the terminating action required by paragraph (g) of this AD is accomplished.

(2) If any cracking is detected, before further flight, do the replacement and modification specified in paragraph (g) of this AD.

Terminating Action

(g) Within 60 months after the effective date of this AD: Replace any existing Krueger flap actuator aluminum support fitting on each wing with a steel fitting, and modify the actuator aft attachment, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-57-1129, Revision 3, dated March 19, 2007. Doing this replacement and modification terminates the repetitive inspection requirements of paragraph (f) of this AD.

Parts Replacement

(h) As of the effective date of this AD, no person may install on any airplane any aluminum support fitting (actuator support assembly) identified in the “Existing Part Number” column of paragraph 2.C. of Boeing Special Attention Service Bulletin 737-57-1129, Revision 3, dated March 19, 2007.

Actions Accomplished in Accordance With Previous Revisions of Service Bulletin

(i) Actions done before the effective date of this AD in accordance with the service bulletins listed in Table 1 of this AD, are acceptable for compliance with the corresponding requirements of this AD.

Table 1.—Previous Revisions of Service Bulletins

Boeing service bulletin	Revision level	Date
737-57-1129	1	Oct. 30, 1981.
737-57-1129	2	May 28, 1998.

Alternative Methods of Compliance (AMOCs)

(j)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Material Incorporated by Reference

(k) You must use Boeing Special Attention Service Bulletin 737-57-1129, Revision 3, dated March 19, 2007, to do the actions required by this AD, unless the AD specifies otherwise.

(1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

(3) You may review copies of the service information incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/​federal_​register/​code_​of_​federal_​regulations/​ibr_​locations.html.

Issued in Renton, Washington, on February 28, 2008.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.