2010-5940. Airworthiness Directives; The Boeing Company Model 747-200C, -200F, -400, -400D, and -400F Series Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Model 747-200C, -200F, -400, -400D, and -400F series airplanes. The existing AD currently requires repetitive inspections for cracks in the overlapping (upper) skin, upper fastener row of the lap joints of the fuselage skin in sections 41, 42, and 46; and related investigative and corrective actions, if necessary. This proposed AD would expand the inspection area in the existing AD, and add a modification of certain lap joints and certain post-repair inspections of the lap joints. Accomplishing the modification would end the repetitive inspections required by the existing AD for the length of lap joint that is modified. This proposed AD results from a structural review of affected skin lap joints for widespread fatigue damage. We are proposing this AD to prevent fatigue cracking in certain lap joints, which could result in rapid depressurization of the airplane.

DATES:

We must receive comments on this proposed AD by May 3, 2010.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; e-mail [e-mail]; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221.

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 proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Ivan Li, 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:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2010-0232; Directorate Identifier 2009-NM-032-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

On February 27, 2006, we issued AD 2006-05-09, amendment 39-14506 (71 FR 12122, March 9, 2006), for certain Model 747-200C, -200F, -400, -400D, and -400F series airplanes. That AD requires repetitive inspections for cracks in the overlapping (upper) skin, upper fastener row of the lap joints of the fuselage skin in sections 41, 42, and 46; and related investigative and corrective actions, if necessary. That AD resulted from fatigue tests and an analysis that identified areas of the fuselage lap joints where fatigue cracks can occur. We issued that AD to detect and correct fatigue cracks in the overlapping (upper) skin, upper fastener row of the lap joints of the fuselage skin in sections 41, 42, and 46, which could adversely affect the structural integrity of the airplane.

Actions Since Existing AD Was Issued

Since we issued AD 2006-05-09, the manufacturer has conducted a structural review of affected skin lap joints for widespread fatigue damage, and has identified additional necessary inspection and modification actions. It is recommended that all lap joints with an upper skin thickness of 0.09 inch or less should be inspected; therefore, the inspection area has been expanded to include a new Area 2 (i.e., the lap joint at STA 450, S-0 to S1L and the S-4L lap joint between STA 1970 and STA 2000). It is also recommended that lap joints in sections 41 and 42 with an upper skin thickness of 0.071 inch or less should be modified; and post-repair inspections have been identified.

Revised Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008. That service bulletin describes procedures for repetitive external surface high frequency eddy current (HFEC), external low frequency eddy current (LFEC), and internal LFEC inspections for cracks in the overlapping (upper) skin, upper fastener row of the lap joints of the fuselage skin in sections 41, 42, and 46; and related investigative and corrective actions, if necessary.

For airplanes on which any crack is found, the related investigative actions include open-hole HFEC inspections of the fastener holes to find further cracking. The corrective actions include repairing any cracked lap joint and an open-hole HFEC inspection of the skin at all existing fastener locations common to the repair. The corrective actions also include repairing any crack found during accomplishment of the inspections.

That service bulletin also describes a modification of the lap joints in sections 41 and 42. The modification includes fabricating and installing skin doublers on affected lap joints.

The compliance time for accomplishing the new Area 2 inspections is before the accumulation of 22,000 total flight cycles, or within 3,000 flight cycles after the last HFEC inspection of that area, as specified in the Boeing Model 747 Supplemental Structural Inspection Document, or within 1,000 flight cycles from the date on Revision 1 of the service bulletin; whichever occurs latest.

For areas on which a lap joint repair was installed and the repair doubler is greater than or equal to 40 inches long, that service bulletin describes procedures for repetitive internal surface HFEC inspections of certain doublers of the lap joints for cracks. The compliance time for accomplishing the inspections is within 15,000 flight cycles after the repair was installed.

That service bulletin specifies repeating the applicable inspection every 3,000 flight cycles, or every 1,500 flight cycles for airplanes that have accumulated 30,000 total flight cycles or more.

The compliance time for accomplishing the new lap joint modification is before the accumulation of 30,000 total flight cycles, or within 3,000 flight cycles from the date of Revision 1 of the service bulletin, whichever is later. Accomplishing this modification eliminates the need for the repetitive inspections for the length of lap joint that is modified.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to develop on other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 2006-05-09 and would retain the requirements of the existing AD. This proposed AD would also require accomplishing the actions specified in the service information described previously.

Explanation of Change Made to This Proposed AD

Boeing Commercial Airplanes has received an Organization Designation Authorization (ODA), which replaces the previous designation as a Delegation Option Authorization (DOA) holder. We have revised paragraph (n)(3) of this proposed AD to add delegation of authority to Boeing Commercial Airplanes ODA to approve an alternative method of compliance for any repair required by this AD.

Change to Existing AD

This proposed AD would retain all requirements of AD 2006-05-09. Since AD 2006-05-09 was issued, we have added a new paragraph to include the ATA code. As a result, the corresponding paragraph identifiers have changed in this proposed AD, as listed in the following table:

Revised Paragraph Identifiers

Requirement in AD 2006-05-09	Corresponding requirement in this proposed AD
paragraph (f)	paragraph (g)
paragraph (g)	paragraph (h)
paragraph (h)	paragraph (l)

Costs of Compliance

There are about 735 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 96 airplanes of U.S. registry.

The actions that are required by AD 2006-05-09 and retained in this proposed AD take about 541 work hours per airplane, at an average labor rate of $85 per work hour. Based on these figures, the estimated cost of the currently required actions is $45,985 per airplane, per inspection cycle.

The new proposed Area 2 inspections would take about 124 work hours per airplane, at an average labor rate of $85 per work hour. Based on these figures, the estimated cost of the new inspections specified in this proposed AD for U.S. operators is $1,011,880, or $10,540 per airplane, per inspection cycle.

The new proposed modification would take about 4,799 work hours per airplane, at an average labor rate of $85 per work hour. Required parts costs per airplane would be minimal. Based on these figures, the estimated cost of the new actions specified in this proposed AD for U.S. operators is $39,159,840, or $407,915 per airplane.

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 proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. 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 proposed 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

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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 removing amendment 39-14506 (71 FR 12122, March 9, 2006) and adding the following new AD:

The Boeing Company: Docket No. FAA-2010-0232; Directorate Identifier 2009-NM-032-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by May 3, 2010.

Affected ADs

(b) This AD supersedes AD 2006-05-09.

Applicability

(c) This AD applies to The Boeing Company Model 747-200C, -200F, -400, -400D, and -400F series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008.

Subject

(d) Air Transport Association (ATA) of America Code 53: Fuselage.

Unsafe Condition

(e) This AD results from a structural review of affected skin lap joints for widespread fatigue damage. The Federal Aviation Administration is issuing this AD to prevent fatigue cracking in certain lap joints, which could result in rapid depressurization of the airplane.

Compliance

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

Restatement of Requirements of AD 2006-05-09, With Revised Service Information

Initial Inspections and Related Investigative and Corrective Actions

(g) For airplanes identified in Boeing Alert Service Bulletin 747-53A2499, dated August 11, 2005: At the applicable time specified in Table 1 of this AD, do an external surface high frequency eddy current (HFEC), external low frequency eddy current (LFEC), and internal LFEC inspection, as applicable, for cracks in the overlapping (upper) skin, upper fastener row of the lap joints of the fuselage skin in sections 41, 42, and 46, and any applicable related investigative and corrective actions by doing all of the actions in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2499, dated August 11, 2005; or Revision 1, dated October 30, 2008. Do any applicable related investigative and corrective actions before further flight. As of the effective date of this AD, only Revision 1, dated October 30, 2008, of Boeing Alert Service Bulletin 747-53A2499 may be used.

Table 1—Initial Compliance Time

For airplanes on which Structural Significant Items (SSIs) F-25G, F-25H, and F-25I—	Inspect—
(1) Have not been inspected in accordance with paragraph (i) of AD 2004-07-22 R1, amendment 39-15326, using the HFEC method	Before the accumulation of 22,000 total flight cycles, or within 1,000 flight cycles after April 13, 2006 (the effective date of AD 2006-05-09), whichever occurs later.
(2) Have been inspected in accordance with paragraph (i) of AD 2004-07-22 R1, using the HFEC method	Within 3,000 flight cycles after the most recent supplemental structural inspection document (SSID) inspection of each applicable structural significant item (as given in Boeing Document D6-35022, “SSID for Model 747 Airplanes,” Revision G, dated December 2000), or within 1,000 flight cycles after April 13, 2006, whichever occurs later.

Repetitive Inspections

(h) Repeat the applicable inspections required by paragraph (g) of this AD thereafter at intervals not to exceed those specified in paragraph 1.E., “Compliance,” (including the note) of Boeing Alert Service Bulletin 747-53A2499, dated August 11, 2005; or Revision 1, dated October 30, 2008. As of the effective date of this AD, only Revision 1, dated October 30, 2008, of Boeing Alert Service Bulletin 747-53A2499 may be used.

New Requirements of This AD

Repetitive Inspections/Investigative and Corrective Actions

(i) For all airplanes: Do an external HFEC inspection of the lap joints in Sections 41, 42, and 46 for cracks, by doing all the actions, including all applicable related investigative and corrective actions, specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008. Do the inspection at the applicable time specified in paragraph 1.E. of Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008; except as required by paragraph (m) of this AD. Do all applicable related investigative and corrective actions before further flight. Repeat the inspection thereafter at the times specified in paragraph 1.E. of Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008. Accomplishment of the inspections required by this paragraph terminates the inspections required by paragraphs (g) and (h) of this AD.

(j) For areas on which a lap joint repair was installed and the repair doubler is greater than or equal to 40 inches long: Do initial and repetitive internal HFEC inspections for cracks by doing all the actions, including all applicable corrective actions, specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008, except as required by paragraph (l) of this AD. Do the inspections and corrective actions at the times specified in paragraph 1.E. of Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008, except as required by paragraph (m) of this AD.

Terminating Action

(k) Modify the applicable lap joints in sections 41 and 42 by doing all the applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008, at the time specified in paragraph 1.E. of Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008; except as required by paragraphs (l) and (m) of this AD. Accomplishing this modification terminates the repetitive inspections of the skin lap joints in sections 41 and 42 required by paragraphs (i) and (j) of this AD for the length of lap joint that is modified.

Exceptions to Service Bulletin Procedures

(l) Where Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008, specifies to contact Boeing for appropriate action, before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (n) of this AD.

(m) Where Boeing Alert Service Bulletin 747-53A2499, Revision 1, dated October 30, 2008, specifies a compliance time after the date of the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD.

Alternative Methods of Compliance (AMOCs)

(n)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Information may be e-mailed to: [e-mail].

(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 principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

(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 the Boeing Commercial Airplanes Organization Designation Authorization (ODA) or other person 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.

(4) AMOCS approved previously in accordance with AD 2006-05-09 are approved as alternative methods of compliance with the corresponding requirements of this AD.

Issued in Renton, Washington, on March 10, 2010.

Jeffrey E. Duven,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.