E6-2170. Airworthiness Directives; Boeing Model 747 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 all Boeing Model 747 series airplanes. The existing AD currently requires repetitive inspections for cracking of the top and side panel webs and panel stiffeners of the nose wheel well (NWW), and corrective actions if necessary. This proposed AD would reduce the interval for certain repetitive inspections and remove a certain optional inspection. This proposed AD would also require replacing the NWW side and top panels with new panels. The replacement would terminate the repetitive inspections. This proposed AD results from the development of a new modification. We are proposing this AD to prevent fatigue cracks in the top and side panel webs and stiffeners of the NWW, which could compromise the structural integrity of the NWW and could lead to the rapid decompression of the airplane.

DATES:

We must receive comments on this proposed AD by April 3, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to

http://dms.dot.gov and follow the instructions for sending your comments electronically.

• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

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

FOR FURTHER INFORMATION CONTACT:

Nick Kusz, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “Docket No. FAA-2006-23921; Directorate Identifier 2005-NM-205-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or may can visit http://dms.dot.gov.

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone [phone]) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

On April 13, 2005, we issued AD 2005-09-02, amendment 39-14070 (70 FR 29940, May 25, 2005), for all Boeing Model 747 series airplanes. That AD requires repetitive inspections for cracking of the top and side panel webs and panel stiffeners of the nose wheel well (NWW), and corrective actions if necessary. That AD resulted from a report of an in-flight decompression of a Model 747-100 series airplane that had accumulated 27,241 total flight cycles. We issued that AD to detect and correct fatigue cracks in the top and side panel webs and stiffeners of the NWW, which could compromise the structural integrity of the NWW and could lead to the rapid decompression of the airplane.

Actions Since Existing AD Was Issued

In the preamble to AD 2005-09-02, we stated that we considered the requirements “interim action” and were considering further rulemaking to reduce certain repetitive inspection intervals. In addition, we explained that the manufacturer was developing a modification and that we would consider additional rulemaking once the modification was developed, approved, and available. We now have determined that further rulemaking is indeed necessary, and this proposed AD follows from that determination.

Relevant Service Information

We have reviewed Boeing Service Bulletin 747-53A2562, Revision 1, dated July 28, 2005. The service bulletin describes procedures for replacing the NWW side and top panels with new panels. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

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 2005-09-02 and would continue to require repetitive inspections for cracking of the top and side panel webs and panel stiffeners of the NWW, and corrective actions if necessary. This proposed AD would also reduce the interval for certain repetitive inspections and would require replacing the NWW side and top panels with new panels. The replacement would terminate the repetitive inspections. The replacement would be accomplished in accordance with the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and Boeing Service Bulletin 747-53A2562.”

Differences Between the Proposed AD and Boeing Service Bulletin 747-53A2562

Boeing Service Bulletin 747-53A2562, Revision 1, dated July 28, 2005, specifies an effectivity of Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747-400, 747-400D, 747SR, and 747SP series airplanes, line numbers 1 through 1307. The service bulletin notes that a future revision will add airplanes with a nose cargo door, and airplanes after line number 1307. This proposed AD is applicable to all Model 747 airplanes. This proposed AD would require that, for Model 747 airplanes identified as Group 1 and 3 in the service bulletin (Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747-400, 747-400D, 747SR, and 747SP series airplanes, line numbers 1 through 1307, except those airplanes modified to the Special Freighter configuration), the replacement of the NWW side and top panels must be done according to the service bulletin. For all Model 747 airplanes identified as Group 2 in the service bulletin and airplanes not identified in the service bulletin, the replacement must be done according to a method approved by the FAA.

Explanation of Change to Applicability

We have revised the applicability of the existing AD to identify model designations as published in the most recent type certificate data sheet for the affected models.

Explanation of Changes Made to Paragraph (f) of This Proposed AD

We have reduced the repetitive inspection intervals for Area 3 from 6,000 flight cycles to 1,500 flight cycles for airplanes on which the inspections have been done in accordance with Boeing Alert Service Bulletin (ASB) 747-53A2465, Revision 2, dated November 11, 2004 (referenced as the appropriate source of service information for doing the inspection specified in paragraph (f)(2)(ii) of the existing AD). In addition, we have removed the optional inspection specified in paragraph (f)(1)(ii) of the existing AD; however, we have given credit for airplanes on which the inspections have been done in accordance with Boeing Service Bulletin 747-53A2465, Revision 1, dated October 16, 2003, for the Area 3 inspections. (Revision 1 was referenced as the appropriate source of service information for doing the inspection specified in paragraph (f)(1)(ii) of the existing AD with a repetitive inspection interval of 1,000 flight cycles.)

Since issuance of Boeing ASB 747-53A2465, Revision 2, Boeing has received additional reports of cracking and has done additional analysis to determine the flight-cycle interval. The 1,500 flight-cycle interval for Area 3 specified in the proposed AD matches the interval specified in Boeing ASB 747-53A2465, Revision 4, dated February 24, 2005 (referenced as the appropriate source of service information for doing the new requirements of the existing AD). We have determined that the 1,500 flight-cycle interval will ensure an acceptable level of safety.

We also removed paragraphs (f)(1)(i) and (f)(2)(i) of the existing AD because all operators will be doing the inspections of the top and sidewall panel webs specified in paragraph (g) of the existing AD. The inspections specified in paragraph (g) of the existing AD terminate the inspections of the top and side panel webs specified in paragraphs (f)(1)(i) and (f)(2)(i) of the existing AD. Therefore we do not need to restate paragraphs (f)(1)(i) and (f)(2)(i) in the proposed AD.

Explanation of Change Made to This Proposed AD

We have simplified paragraph (l) of this proposed AD by referring to the “Alternative Methods of Compliance (AMOCs)” paragraph of this proposed AD for repair methods and we have revised the AMOCs paragraph in this proposed AD to clarify the delegation authority for Authorized Representatives for the Boeing Commercial Airplanes Delegation Option Authorization.

Clarification of AMOC Paragraph

We have revised this action to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies.

Costs of Compliance

There are about 1,127 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. Work hours are estimated at an average labor rate of $65 per work hour.

Estimated Costs

Action	Work hours	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Area 1 and 3 inspections (required by AD 2005-09-02)	79	$0	$5,135, per inspection cycle	255	$1,309,425, per inspection cycle.
Area 2 inspections (required by AD 2005-09-02)	8-18	0	$520-$1,170, per inspection cycle	255	Up to $298,350, per inspection cycle.
Replacement (new proposed action)	800	115,765	$167,765	255	$42,780,075.

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
• 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 Federal Aviation Administration (FAA) amends § 39.13 by removing amendment 39-14070 (70 FR 29940, May 25, 2005) and adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-23921; Directorate Identifier 2005-NM-205-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by April 3, 2006.

Affected ADs

(b) This AD supersedes AD 2005-09-02.

Applicability

(c) This AD applies to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from the development of a new modification. We are issuing this AD to prevent fatigue cracks in the top and side panel webs and stiffeners of the nose wheel well (NWW), which could compromise the structural integrity of the NWW and lead to the rapid decompression 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.

Restatement of Requirements of AD 2005-09-02 With New Repetitive Interval and Service Information

Initial and Repetitive Inspections of the Top and Side Panel Stiffeners

(f) Prior to the accumulation of 16,000 total flight cycles, or within 1,000 flight cycles after January 27, 2005 (the effective date of AD 2004-25-23, amendment 39-13911), whichever is later, do internal detailed and surface high frequency eddy current (HFEC) inspections of the top and side panel stiffeners of the NWW (specified as Area 3 in the service bulletin) for cracks in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin (ASB) 747-53A2465, Revision 4, dated February 25, 2005. Repeat the inspections thereafter at the compliance times specified in paragraph (f)(1) or (f)(2) of this AD, as applicable.

(1) For airplanes on which an inspection has not been done before the effective date of this AD in accordance with any service bulletin listed in Table 1 of this AD: Within 1,500 flight cycles after doing the inspection specified in paragraph (f) of this AD, repeat the inspection. Repeat the inspection thereafter at intervals not to exceed 1,500 flight cycles.

(2) For airplanes on which an inspection has been done before the effective date of this AD in accordance with any service bulletin listed in Table 1 of this AD: Within 6,000 flight cycles after doing the inspection specified in paragraph (f) of this AD or within 1,500 flight cycles after the effective date of this AD, whichever occurs first, repeat the inspection. Repeat the inspection thereafter at intervals not to exceed 1,500 flight cycles.

Table 1.—Boeing Service Bulletins

Service bulletin	Revision level	Date
Boeing ASB 747-53A2465	(1)	April 5, 2001.
Boeing Service Bulletin 747-53A2465	1	October 16, 2003.
Boeing ASB 747-53A2465	2	November 11, 2004.
Boeing ASB 747-53A2465	3	December 23, 2004.
Boeing ASB 747-53A2465	4	February 25, 2005.
1 Original.

Note 1:

For the purposes of this AD, a detailed inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirrors, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Initial Inspections of the Top and Sidewall Panel Webs

(g) Do an external detailed inspection of the top and sidewall panel webs of the NWW (specified as Area 1 and Area 2 in the service bulletin) for cracks, in accordance with the Accomplishment Instructions of Boeing ASB 747-53A2465, Revision 4, dated February 24, 2005, at the earlier of the times specified in paragraphs (g)(1) and (g)(2) of this AD.

(1) At the later of the times specified in paragraph (g)(1)(i) and (g)(1)(ii) of this AD:

(i) Before accumulating 20,000 total flight cycles.

(ii) Within 100 flight cycles or 90 days after May 10, 2005 (the effective date of AD 2005-09-02), whichever occurs first.

(2) At the later of the times specified in paragraphs (g)(2)(i) and (g)(2)(ii) of this AD:

(i) Before accumulating 16,000 total flight cycles.

(ii) Within 1,000 flight cycles after May 10, 2005.

Repetitive Inspections of the Top and Sidewall Panel Webs

(h) Repeat the inspection required by paragraph (g) of this AD at the intervals specified in paragraphs (h)(1) and (h)(2) of this AD, as applicable.

(1) For airplanes with fewer than 20,000 total flight cycles as of May 10, 2005, repeat at intervals not to exceed 1,000 flight cycles until the first inspection after the airplane reaches 20,000 total flight cycles.

(2) For airplanes with 20,000 total flight cycles or more, repeat at intervals not to exceed 500 flight cycles.

Ultrasonic Inspections (UT)

(i) Do a UT inspection of the top and sidewall panel webs for cracks, in accordance with Boeing ASB 747-53A2465, Revision 4, dated February 24, 2005, at the later of the times specified in paragraphs (i)(1) and (i)(2) of this AD. Repeat the inspections thereafter at intervals not to exceed 500 flight cycles.

(1) Prior to the accumulation of 20,000 total flight cycles.

(2) Within 100 flight cycles or 90 days after May 10, 2005, whichever occurs first.

Additional Inspections and Corrective Actions

(j) Except as specified in paragraph (l) of this AD, if any crack is found during any inspection required by this AD, prior to further flight, do any applicable additional detailed inspections of stiffeners and beams and make repairs, in accordance with the Accomplishment Instructions of Boeing ASB 747-53A2465, Revision 4, dated February 24, 2005.

Actions Accomplished Per Previous Issues of Service Bulletin

(k) The actions specified in paragraphs (k)(1), (k)(2), and (k)(3) of this AD are acceptable for compliance with the corresponding action specified in the applicable paragraph.

(1) Inspections and corrective actions accomplished before January 27, 2005, in accordance with Boeing ASB 747-53A2465, dated April 5, 2001, are considered acceptable for compliance with the corresponding inspections specified in paragraph (f) of this AD.

(2) Inspections accomplished before the effective date of this AD, in accordance with Boeing Service Bulletin 747-53A2465, Revision 1, dated October 16, 2003; Boeing ASB 747-53A2465, Revision 2, dated November 11, 2004; and Boeing ASB 747-53A2465, Revision 3, dated December 23, 2004; are considered acceptable for compliance with the corresponding inspections specified in paragraph (f) of this AD.

Note 2:

The detailed and surface HFEC inspections of the top and side panel stiffeners of the NWW specified in Boeing ASB 747-53A2465, dated April 5, 2001; and Boeing Service Bulletin 747-53A2465, Revision 1, dated October 16, 2003; are acceptable for compliance with the internal detailed and surface HFEC inspections specified in paragraph (f) of this AD.

(3) Inspections and corrective actions accomplished before May 10, 2005, in accordance with Boeing Service Bulletin 747-53A2465, Revision 1, dated October 16, 2003; Boeing ASB 747-53A2465, Revision 2, dated November 11, 2004; and Boeing ASB 747-53A2465, Revision 3, dated December 23, 2004; are considered acceptable for compliance with the corresponding inspections specified in paragraphs (g) and (h) of this AD.

Certain Other Corrective Actions

(l) Where Boeing ASB 747-53A2465 specifies contacting the manufacturer if certain cracking is found, this AD requires, before further flight, repairing the cracking using a method approved in accordance with the procedures specified in paragraph (p) of this AD.

No Reporting Requirement

(m) Although Boeing ASB 747-53A2465 specifies that operators should report inspection results to the manufacturer, this AD does not require those inspection results to be reported.

New Requirements of This AD

Terminating Action

(n) For Group 1 and 3 airplanes identified in Boeing Service Bulletin 747-53A2562, Revision 1, dated July 28, 2005: Before accumulating 22,000 total flight cycles or within 48 months after the effective date of this AD, whichever occurs later, replace the NWW side and top panels with new panels in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-53A2562, Revision 1, dated July 28, 2005. Doing the replacement terminates the requirements of this AD.

(o) For Group 2 airplanes identified in Boeing Service Bulletin 747-53A2562, Revision 1, dated July 28, 2005, and Model 747 airplanes not identified in the service bulletin: Before accumulating 22,000 total flight cycles or within 48 months after the effective date of this AD, whichever occurs later, replace the NWW side and top panels using a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Doing the replacement terminates the requirements of this AD.

Alternative Methods of Compliance (AMOCs)

(p)(1) The Manager, Seattle 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) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

(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.

(4) AMOCs approved previously according to AD 2005-09-02, amendment 39-14070, are approved as AMOCs for the corresponding provisions of paragraphs (f) through (j) and (l) of this AD.

(5) AMOCs approved previously according to AD 2004-25-23, amendment 39-13911, are approved as AMOCs for the corresponding provisions of paragraph (f) of this AD.

Issued in Renton, Washington, on January 26, 2006.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.