E9-18641. Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747-400, 747SR, and 747SP 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 Boeing Model 747 airplanes. The existing AD currently requires repetitive inspections for cracking, and repair as necessary, of lower lobe body frames (sections 42 and 46) of the fuselage. The existing AD also provides for optional modification of the frames, which terminates the repetitive inspections. This proposed AD would require additional repetitive inspections for cracking of certain fuselage frames, and corrective actions if necessary. This proposed AD would also revise the AD applicability. This proposed AD results from a new report of a crack found in a body frame with a tapered side guide bracket at fuselage station 1800, located on the left side between stringers 39 and 40; the frame was severed. We are proposing this AD to detect and correct the loss of structural integrity of the fuselage, which could result in rapid depressurization of the airplane.

DATES:

We must receive comments on this proposed AD by September 21, 2009.

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 or 425-227-1152.

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-2009-0682; Directorate Identifier 2008-NM-200-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 August 4, 1986, we issued AD 86-18-01, amendment 39-5390 (51 FR 28691, August 11, 1986), for certain Boeing Model 747 airplanes. That AD requires repetitive inspections for cracking, and repair as necessary, of lower lobe body frames (sections 42 and 46) of the fuselage. That AD also provides for optional modification of the frames, which terminates the repetitive inspections. That AD resulted from a finding of numerous body frame cracks in the lower lobe of the fuselage. We issued that AD to prevent failure of the structure, which could lead to rapid decompression of the airplane.

Actions Since Existing AD was Issued

Since we issued AD 86-18-01, we received a report of a crack found in a body frame with a tapered side guide bracket at fuselage station 1800. The body frame was located on the left side between stringers 39 and 40 and was severed. Investigation revealed that frames with tapered side guide brackets and frames with the optional terminating action incorporated are also susceptible to cracking. As a result, we have determined that additional inspections are necessary, as specified in the service information described below. In addition, we have determined that it is necessary to revise the AD applicability to include the affected frames on certain other airplanes, as specified in the service information described below.

Other Related Rulemaking

On February 16, 2006, we issued AD 2006-05-02, amendment 39-14499 (71 FR 10605, March 2, 2006), for all Boeing Model 747-200F, 747-200C, 747-400, 747-400D, and 747-400F series airplanes. That AD requires repetitive inspections for cracking of certain fuselage internal structure, and repair if necessary. That AD resulted from fatigue tests and analysis that identified areas of the fuselage where fatigue cracks can occur. We issued that AD to prevent loss of the structural integrity of the fuselage, which could result in rapid depressurization of the airplane.

On September 26, 2005, we issued AD 2005-20-30, amendment 39-14327 (70 FR 59252, October 12, 2005), for certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747SP, and 747SR series airplanes. That AD supersedes an existing AD and requires repetitive inspections to detect cracks in various areas of the fuselage internal structure, and repair if necessary. That AD also requires repetitive inspections of additional areas of the fuselage internal structure, and related investigative/corrective actions if necessary. That AD also removes certain requirements from the existing AD. That AD resulted from fatigue testing of the fuselage structure of a Boeing Model 747SR series airplane. We issued that AD to prevent the loss of the structural integrity of the fuselage, which could result in rapid depressurization of the airplane.

The inspections specified in this proposed AD are not necessary on airplanes on which the repetitive inspections have been done in accordance with AD 2005-20-30 and AD 2006-05-02.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2749, dated September 25, 2008. The service bulletin describes procedures for a detailed inspection for cracking of the inner chord and vertical web of the left and right side body frames from fuselage stations 1500 to 1800, stringers 39 to 40; and corrective actions if necessary. The corrective action is repairing any crack found.

For airplanes that have accumulated 22,000 total flight cycles or more, the service bulletin specifies that no work is necessary. Those airplanes are being inspected per the requirements of AD 2005-20-30 or AD 2006-05-02, as applicable.

For all other airplanes, the compliance time for the detailed inspection for cracking of the inner chord and vertical web is before the accumulation of 10,000 total flight cycles, or 10,000 flight cycles after installation of a tapered strap, or within a specified grace period. The grace period is either 2,000 flight cycles after the date on the service bulletin or 3,000 flight cycles after the most recent inspection, depending on the airplane configuration and inspection status.

The service bulletin specifies repeating the inspection every 3,000 flight cycles until the accumulation of 22,000 total flight cycles.

The service bulletin also includes doing a detailed inspection for cracks in any existing repair and the adjacent structure, and corrective actions if necessary. The service bulletin also provides for optional installation of a tapered strap if no crack is found, which extends the repetitive inspection interval.

The service bulletin specifies doing the detailed inspection of the repair within 3,000 flight cycles or 10,000 flight cycles after the repair was done, depending on whether a tapered strap is installed. The service bulletin also specifies repeating the inspection every 3,000 flight cycles until the accumulation of 22,000 total flight cycles.

The service bulletin also recommends as a corrective action contacting Boeing before further flight for repair instructions if cracking is found on the installed repair, tapered strap, or adjacent structure.

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 airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 86-18-01 and would retain the requirements of the existing AD. This proposed AD would also require accomplishing the actions specified in Boeing Alert Service Bulletin 747-53A2749, dated September 25, 2008, described previously.

Change to Existing AD

This proposed AD would retain the requirements of AD 86-18-01. Since AD 86-18-01 was issued, the AD format has been revised, and certain paragraphs have been rearranged. 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 86-18-01	Corresponding requirement in this proposed AD
Paragraph A	Paragraph (g).
Paragraph B	Paragraph (h).
Paragraph C	Paragraph (i).
Paragraph D	Paragraph (j).

Costs of Compliance

There are about 237 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Inspections (required by AD 86-18-01)	370	$80	$29,600, per inspection cycle	112	$3,315,200, per inspection cycle.
Additional inspections (new proposed action)	6	80	$480, per inspection cycle	87	$41,760, per inspection cycle.

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 39-5390 (51 FR 28691, August 11, 1986), and adding the following new AD:

Boeing: Docket No. FAA-2009-0682; Directorate Identifier 2008-NM-200-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by September 21, 2009.

Affected ADs

(b) This AD supersedes AD 86-18-01.

Applicability

(c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747-400, 747SR, and 747SP series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 747-53A2749, dated September 25, 2008.

Subject

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

Unsafe Condition

(e) This AD results from a report of a crack found in a body frame with a tapered side guide bracket at fuselage station 1800, located on the left side between stringers 39 and 40; the frame was severed. The Federal Aviation Administration is issuing this AD to detect and correct the loss of structural integrity of the fuselage, 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 86-18-01, with Revised Service Information

Repetitive Inspections

(g) For airplanes listed in Boeing Alert Service Bulletin 747-53A2237, Revision 1, dated March 28, 1986: Perform a detailed visual inspection for frame cracking from fuselage section 540 to 760, and 1820 to 1900, stringers 35 left to 42 left, in accordance with Section III of Boeing Alert Service Bulletin 747-53A2237, Revision 1, dated March 28, 1986. Do the inspection at the time specified in paragraph (g)(1), (g)(2), or (g)(3) of this AD, as applicable. If any crack is found, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or using a method approved in accordance with the procedures specified in paragraph (p) of this AD. Repeat the inspection at intervals not to exceed 3,000 landings until the terminating action specified in paragraph (g)(4) or (k) of this AD is performed.

(1) Within 300 landings for airplanes that have accumulated more than 12,000 landings on September 17, 1986 (the effective date of AD 86-18-01, amendment 39-5390).

(2) Within 800 landings for airplanes that have accumulated 10,000 to 12,000 landings on September 17, 1986.

(3) Within 800 landings or prior to the accumulation of 10,000 landings, whichever occurs later, for airplanes that have accumulated less than 10,000 landings on September 17, 1986.

(4) Modification of the frames before the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-53A2237, Revision 1, dated March 28, 1986, constitutes terminating action for the repetitive inspections required by paragraph (g) of this AD.

(h) For airplanes listed in Boeing Alert Service Bulletin 747-53A2259, Revision 1, dated April 18, 1986: Perform a visual inspection of cargo side guide support brackets from fuselage station 1500 to 1800, right and left hand side, for a proper machined taper in accordance with Section III of Boeing Alert Service Bulletin 747-53A2259, Revision 1, dated April 18, 1986. Do the inspection at the time specified in paragraph (h)(1), (h)(2), or (h)(3) of this AD, as applicable. If any cargo side guide support bracket is improperly tapered, perform a detailed visual inspection of the frame area adjacent to the untapered bracket for cracking in accordance with Boeing Alert Service Bulletin 747-53A2259, Revision 1, dated April 18, 1986. If any crack is found, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or using a method approved in accordance with the procedures specified in paragraph (p) of this AD. Repeat the detailed visual inspection at intervals not to exceed 3,000 landings until the terminating action specified in paragraph (h)(4) of this AD is performed. Accomplishment of the inspections required by paragraph (k) of this AD terminates the inspections required by this paragraph.

(1) Within 300 landings for airplanes that have accumulated more than 12,000 landings on September 17, 1986 (the effective date of AD 86-18-01, amendment 39-5390).

(2) Within 800 landings for airplanes that have accumulated 10,000 to 12,000 landings on September 17, 1986.

(3) Within 800 landings or prior to the accumulation of 10,000 landings, whichever occurs later, for airplanes that have accumulated less than 10,000 landings on September 17, 1986.

(4) Installation of a tapered strap adjacent to the affected brackets before the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-53A2259, Revision 1, dated April 18, 1986, constitutes terminating action for the repetitive inspections required by paragraph (h) of this AD.

(i) For Boeing Model 747SR airplanes only, based on continued mixed operation of cabin pressure differentials, the initial inspection thresholds and reinspection intervals specified in AD 86-18-01 may be multiplied by a 1.2 adjustment factor. This provision is not applicable to paragraphs (k), (m), and (n) of this AD.

(j) For the purposes of complying with AD 86-18-01, the number of landings may be determined to equal the number of pressurization cycles where the cabin pressure differential was greater than 2.0 pounds per square inch. This provision is not applicable to paragraphs (k), (m), and (n) of this AD.

New Requirements of this AD

Repetitive Inspections

(k) For airplanes identified in Boeing Alert Service Bulletin 747-53A2749, dated September 25, 2008, that have accumulated 22,000 or fewer total flight cycles as of the effective date of this AD: Do initial and repetitive detailed inspections for frame cracking from fuselage body stations 1500 to 1800, stringers 39 to 40, by doing all the actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2749, dated September 25, 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 747-53A2749, dated September 25, 2008, except as required by paragraphs (m) and (n) of this AD. Accomplishment of the inspections required by this paragraph terminates the inspections required by paragraph (h) of this AD.

Exceptions to Service Bulletin Procedures

(l) If any crack is found during any inspection required by this AD, and Boeing Alert Service Bulletin 747-53A2749, dated September 25, 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 (p) of this AD.

(m) Where Boeing Alert Service Bulletin 747-53A2749, dated September 25, 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.

(n) Where Boeing Alert Service Bulletin 747-53A2749, dated September 25, 2008, specifies a compliance time related to accomplishing an action “as given in Boeing Service Bulletin 747-53A2259,” this AD requires compliance within the specified compliance time after the applicable compliance time required by paragraph (h) of this AD.

Terminating Action

(o) Accomplishing the repetitive frame inspections required by AD 2006-05-02, amendment 39-14499, or AD 2005-20-30, amendment 39-14327, terminates the inspections required by paragraphs (g), (h), and (k) of this AD.

Alternative Methods of Compliance (AMOCs)

(p)(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 Attn: 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]; or, e-mail information 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) AMOCs approved previously in accordance with paragraph (A) of AD 86-18-01, are approved as alternative methods of compliance with the corresponding requirements of paragraph (g) of this AD.

(4) AMOCs approved previously in accordance with paragraph (B) of AD 86-18-01, are approved as alternative methods of compliance with the corresponding requirements of paragraph (h) of this AD.

(5) 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.

Issued in Renton, Washington, on July 24, 2009.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.