E7-24520. Airworthiness Directives; Boeing Model 747-200B, 747-300, 747-400, 747-400D, and 747-400F Series Airplanes Equipped with General Electric CF6-80C2 Engines

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Final rule.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 747-200B, 747-300, 747-400, 747-400D, and 747-400F series airplanes. This AD requires repetitive inspections of the left- and right-hand flipper door assemblies of the engine core cowls for migrated pins and damaged flipper doors, and corrective actions if necessary. Modification of the hinge assemblies terminates the repetitive inspections. This AD results from two reports of missing flipper doors for the engine core cowls. We are issuing this AD to detect and correct migrated hinge pins and damaged flipper doors, which could allow the flipper door to fall off, resulting in the potential for an engine fire to propagate into the flammable leakage zone of the strut and for the amount of fire extinguishing agent reaching the fire to be diluted, and subsequent uncontained fire in the engine strut.

DATES:

This AD becomes effective February 1, 2008.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in the AD as of February 1, 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:

Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Boeing Model 747-200B, 747-300, 747-400, 747-400D, and 747-400F series airplanes. That NPRM was published in the Federal Register on June 5, 2007 (72 FR 31001). That NPRM proposed to require repetitive inspections of the left- and right-hand flipper door assemblies of the engine core cowls for migrated pins and damaged flipper doors, and corrective actions if necessary. That NPRM specified that the modification of the hinge assemblies would terminate the repetitive inspections.

Comments

We provided the public the opportunity to participate in the development of this AD. We have considered the comments received.

Request to Clarify the Requirements Specified in Paragraph (f) of the NPRM

Boeing requests that we revise paragraph (f) of the NPRM to clarify that the modification specified in Boeing Special Attention Service Bulletin 747-71-2310, dated October 13, 2005, is necessary only if hinge pins have migrated or flipper doors are damaged or missing. Boeing states that the instruction to do all applicable corrective actions could be interpreted to mean that the proposed modification is required, regardless of the inspection findings.

We agree that modification is necessary only when hinge pins have migrated or the flipper doors are damaged or missing. Both Boeing Special Attention Service Bulletin 747-71-2310, and Rohr Service Bulletin TBC/80C2-NAC-71-035, dated October 10, 2005, clearly state that modification is necessary only when hinge pins have migrated or the flipper doors are damaged or missing. We have made no change to the AD in this regard.

Request to Clarify the Requirements Specified in Paragraph (g) of the NPRM

Boeing requests that we revise paragraph (g) of the NPRM to clarify that accomplishing Rohr Service Bulletin TBC/80C2-NAC-71-035, as instructed in Boeing Special Attention Service Bulletin 747-71-2310, does not necessarily result in modification of the core cowl. Boeing points out that, if the hinge pin is properly installed, modification in accordance with Rohr Service Bulletin TBC/80C2-NAC-71-035 is not necessary.

We agree with Boeing's comment. The actions specified in Rohr Service Bulletin TBC/80C2-NAC-71-035 do not require modification if the hinge pin has not migrated and is properly peened. We have changed paragraph (g) of this AD to say that accomplishment of the Rohr service bulletin terminates the repetitive inspection requirements (for non-discrepant hinge pins) of paragraph (f) of this AD.

Conclusion

We reviewed the relevant data, considered the comments received from the single commenter, and determined that air safety and the public interest require adopting the AD with the change described previously. We also determined that this change will not increase the economic burden on any operator or increase the scope of the AD.

Costs of Compliance

There are about 297 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 of flipper door assemblies, per inspection cycle	1	$80	$0	$80, per inspection cycle	42	$3,360, per inspection cycle.
Modification of hinge assemblies, if accomplished	1	80	0	80	Up to 42	Up to $3,360.

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

We have determined that 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.

We prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

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 Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

2007-26-07 Boeing: Amendment 39-15309. Docket No. FAA-2007-28352; Directorate Identifier 2007-NM-037-AD.

Effective Date

(a) This AD becomes effective February 1, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 747-200B, 747-300, 747-400, 747-400D, and 747-400F series airplanes, certificated in any category, equipped with General Electric CF6-80C2 engines.

Unsafe Condition

(d) This AD results from two reports of missing flipper doors for the engine core cowl. We are issuing this AD to detect and correct migrated hinge pins and damaged flipper doors, which could allow the flipper door to fall off, resulting in the potential for an engine fire to propagate into the flammable leakage zone of the strut and for the amount of fire extinguishing agent reaching the fire to be diluted, and subsequent uncontained fire in the engine strut.

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.

Inspection of the Flipper Door Assemblies

(f) Within 24 months after the effective date of this AD: Do a general visual inspection for migrated hinge pins and damaged flipper doors of the left- and right-hand flipper door assemblies of the engine core cowls, and do all applicable corrective actions, by accomplishing all the actions specified in the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-71-2310, dated October 13, 2005. Do all applicable corrective actions before further flight. Repeat the inspection thereafter at intervals not to exceed 18 months for that flipper door assembly, until doing the actions specified in paragraph (g) of this AD.

Note 1:

Boeing Special Attention Service Bulletin 747-71-2310, dated October 13, 2005, refers to Rohr Service Bulletin TBC/80C2-NAC-71-035, dated October 10, 2005, as an additional source of service information for accomplishing the actions specified in paragraph (f) of this AD.

Terminating Action for Repetitive Inspections

(g) Accomplishing the inspection and applicable modification of a hinge assembly of a flipper door assembly of the engine core cowl in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-71-2310, dated October 13, 2005; or Rohr Service Bulletin TBC/80C2-NAC-71-035, dated October 10, 2005; terminates the repetitive inspection requirements of this AD for that hinge assembly.

Parts Installation

(h) As of the effective date of this AD, no person may install, on any airplane, a hinge assembly, part number 224-2335-69, for the flipper door of the engine core cowl unless it has been modified in accordance with the requirements of paragraph (g) of this AD.

Material Incorporated by Reference

(i) You must use Boeing Special Attention Service Bulletin 747-71-2310, dated October 13, 2005, to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approved the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for a copy of this service information. You may review copies 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/​cfr/​ibr-locations.html.

Issued in Renton, Washington, on December 11, 2007.

Michael J. Kaszycki,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.