E6-9721. 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 airplanes. The existing AD currently requires a one-time inspection to determine whether the outer cylinder of the wing landing gear has certain part numbers (P/Ns), and replacement of the outer cylinder of the wing landing gear with a new, improved, or reworked part if necessary. The existing AD also requires removal of the load evening system, if such a system is installed. For certain airplanes, this proposed AD would require an additional one-time inspection to determine whether the outer cylinder has a certain other P/N. For those certain airplanes, this proposed AD would also require replacement of the outer cylinder with a reworked or new, improved part and related investigative/corrective actions, if necessary. This proposed AD results from identification of an additional unsafe part. We are proposing this AD to prevent fracture of the outer cylinder of the wing landing gear, which could result in collapse of the wing landing gear.

DATES:

We must receive comments on this proposed AD by August 7, 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:

Nicholas Kusz, Aerospace Engineer, 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-2006-25087; Directorate Identifier 2006-NM-053-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 July 27, 2004, we issued AD 2004-16-05, amendment 39-13761 (69 FR 48359, August 10, 2004), for all Boeing Model 747 airplanes. That AD requires a one-time inspection to determine whether the outer cylinder of the wing landing gear has certain part numbers (P/Ns), and replacement of the outer cylinder of the wing landing gear with a new, improved, or reworked part if necessary. That AD also requires removal of the load evening system, if such a system is installed. That AD resulted from reports that the outer cylinder of the wing landing gear was found cracked or fractured on Model 747 airplanes. We issued that AD to prevent fracture of the outer cylinder of the wing landing gear, which could result in collapse of the wing landing gear.

Actions Since Existing AD Was Issued

Since we issued AD 2004-16-05, Boeing has published Service Bulletin 747-32-2472, Revision 1, dated February 23, 2006, to identify an outer cylinder, P/N 65B01382-( ), which was inadvertently omitted from the original issue of the service bulletin, dated November 30, 2000. We referenced the original service bulletin as the appropriate source of service information for accomplishing the inspection and replacement required by the existing AD. (The procedures in Revision 1 are essentially the same as those in the original service bulletin.) P/N 65B01382-( ) has chrome plating on its inner surface, similar to the other unsafe parts identified in the original service bulletin and existing AD. Therefore, P/N 65B01382-( ) is also subject to the same unsafe condition addressed by the existing AD.

Since P/N 65B01382-( ) was fitted exclusively to Model 747-100, 747-100B, 747-100B SUD, and 747SR series airplanes, this NPRM proposes to require an additional one-time inspection to determine the P/Ns of the outer cylinder of the wing landing only on these airplanes. For any of these airplanes equipped with a load evening system, this NPRM would also require removal of that system before replacing P/N 65B01382-( ) with a reworked or new, improved part if applicable. We have added that requirement to paragraphs (h) and (j) of this NPRM. (Paragraph (h) of the NPRM corresponds to paragraph (c) of the existing AD.)

Relevant Service Information

We have reviewed Revision 1 of Boeing Service Bulletin 747-32-2472. The service bulletin describes procedures for doing a one-time inspection to determine the P/N of the outer cylinder of the wing landing gear. The service bulletin also describes procedures for replacing the outer cylinder with a reworked or new part and doing related investigative and corrective actions, if an outer cylinder having P/N 65B01212-( ), 65B01382-( ), 65B01430-3, or 65B01430-4 is installed on an airplane. The related investigative actions include the following:

• Doing a nital etch test of the upper inner surface of the outer cylinder for chrome plating.
• Doing a magnetic particle inspection of the outer cylinder for any cracking.
• Doing a nital etch inspection of inner surface of the outer cylinder for heat damage.
• Marking the outer cylinder to indicate that part has been reworked.

The corrective actions include the following:

• Removing any chrome plating found on the upper inner surface of the outer cylinder.
• Reworking the outer cylinder to remove any cracking or heat damage.

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 2004-16-05 and would retain the requirements of the existing AD. This proposed AD would also require accomplishing the actions specified in the service bulletin described previously, except as discussed under “Differences Between the Proposed AD and Service Bulletin.”

Differences Between the Proposed AD and Service Bulletin

Service Bulletin 747-32-2472, Revision 1, specifies that operators may accomplish certain related investigative and corrective actions using an “approved equivalent procedure.” However, this proposed AD would require operators to accomplish the actions using the procedures specified in a certain chapter(s) of the Boeing 747 SOPM or OHM, as applicable. An “approved equivalent procedure” may be used only if approved as an alternative method of compliance according to paragraph (m) of this AD.

Changes to Existing AD

This proposed AD would retain certain requirements of AD 2004-16-05. Since AD 2004-16-05 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 2004-16-05	Corresponding requirement in this proposed AD
Paragraph (a)	Paragraph (f).
Paragraph (b)	Paragraph (g).
Paragraph (c)	Paragraph (h).
Paragraph (d)	Paragraph (i).

We have added reference to Revision 1 of Boeing Service Bulletin 747-32-2472 in paragraphs (f) and (g) of this proposed AD, since the procedures in Revision 1 are essentially the same as those in the original issue of the service bulletin.

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

We have also revised this proposed AD 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 1,106 Model 747 airplanes of the affected design in the worldwide fleet. Of those airplanes, there are about 66 Model 747-100, 747-100B, 747-100B SUD, and 747SR series airplanes of the affected design in the worldwide fleet that would be subject to the new proposed actions. The following table provides the estimated costs, at an average labor rate of $80 per hour, for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Inspection for all airplanes (required by AD 2004-16-05)	1	None	$80	256	$20,480
Removal of the load evening system (required by AD 2004-16-05)	240	$2,392	21,592	256	5,527,552
Inspection for certain airplanes (new proposed action)	1	None	80	21	1,680

If required, the chrome removal and inspections for cracking or heat damage would take about 12 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of these actions is $960 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
• 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 39-13761 (69 FR 48359, August 10, 2004) and adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-25087; Directorate Identifier 2006-NM-053-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by August 7, 2006.

Affected ADs

(b) This AD supersedes AD 2004-16-05.

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 identification of an additional unsafe outer cylinder of the wing landing gear. We are issuing this AD to prevent fracture of the outer cylinder of the wing landing gear, which could result in collapse of the wing landing gear.

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 2004-16-05

Inspection to Determine Part Number

(f) Within 36 months after September 14, 2004 (the effective date of AD 2004-16-05), perform a one-time inspection to determine the part number (P/N) of the outer cylinder of the wing landing gear on both sides of the airplane, per the Accomplishment Instructions of Boeing Service Bulletin 747-32-2472, dated November 30, 2000, or Revision 1, dated February 23, 2006. Instead of inspecting the outer cylinder of the wing landing gear, a review of airplane maintenance records is acceptable if the detailed P/N of the outer cylinder of the wing landing gear (not just a higher-level assembly) can be positively determined from that review.

(1) If no outer cylinder having P/N 65B01212-( ) (where “( )” is any dash number of that part number), 65B01430-3, or 65B01430-4 is found: No further action is required by this paragraph.

(2) If any outer cylinder having P/N 65B01212-( ) (where “( )” is any dash number of that part number), 65B01430-3, or 65B01430-4 is found: Accomplish paragraph (g) of this AD.

Replacement of Outer Cylinder

(g) For any outer cylinder identified in paragraph (f)(2) of this AD: Within 36 months after September 14, 2004, replace the outer cylinder on the wing landing gear with a new, improved part or a part that has been inspected and reworked per the Accomplishment Instructions of Boeing Service Bulletin 747-32-2472, dated November 30, 2000; or Revision 1, dated February 23, 2006, except as provided by paragraph (k) of this AD. The rework procedures described in the service bulletin, if accomplished, include performing a one-time nital etch inspection of the upper inner surface of the outer cylinder for chrome plating; removing any chrome plating that is present; performing a one-time magnetic particle inspection for cracking of the outer cylinder; performing a nital etch inspection for heat damage of the outer cylinder; reworking the outer cylinder, as applicable; and marking the outer cylinder to indicate that the service bulletin has been accomplished.

Removal of the Load Evening System

(h) For airplanes identified in Boeing Service Bulletin 747-32-2131, Revision 2, dated March 15, 1974: Before performing the requirements of paragraph (g) or (j) of this AD, as applicable, remove the load evening system installed on the wing landing gear, per the Accomplishment Instructions of the service bulletin.

New Requirements of This AD

Inspection To Determine Outer Cylinder P/N on Certain Airplanes

(i) For Model 747-100, 747-100B, 747-100B SUD, and 747SR series airplanes: Within 36 months after the effective date of this AD, do a one-time inspection to determine the P/N of the outer cylinder of the wing landing gear on both sides of the airplane, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-32-2472, Revision 1, dated February 23, 2006. Instead of inspecting the outer cylinder of the wing landing gear, a review of airplane maintenance records is acceptable if the detailed P/N of the outer cylinder of the wing landing gear (not just a higher-level assembly) can be positively determined from that review.

(1) If no outer cylinder having P/N 65B01382-( ) is found: No further action is required by this paragraph.

(2) If any outer cylinder having P/N 65B01382-( ) is found: Accomplish paragraph (j) of this AD.

Replacement of a Certain Outer Cylinder

(j) For any outer cylinder identified in paragraph (i)(2) of this AD: Within 36 months after the effective date of this AD, replace the outer cylinder on the wing landing gear with a reworked or new, improved part, and do the related investigative actions and all applicable corrective actions before further flight after the replacement, by accomplishing all of the applicable actions specified in 3.B.2 and 3.B.3 of the Accomplishment Instructions of Boeing Service Bulletin 747-32-2472, Revision 1, dated February 23, 2006; except as provided by paragraph (k) of this AD. If applicable, do the actions specified in paragraph (h) of this AD before accomplishing the actions specified in this paragraph.

Exception to Revision 1 of the Service Bulletin

(k) Where Service Bulletin 747-32-2472, Revision 1, dated February 23, 2006, specifies that the related investigative and corrective actions may be accomplished using an operator's “equivalent procedure:” The related investigative and corrective actions must be accomplished in accordance with the chapter(s) of the applicable Boeing 747 SOPM or OHM specified in the service bulletin.

Parts Installation

(l) As of September 14, 2004, no person may install, on any airplane, an outer cylinder of the wing landing gear if the outer cylinder has P/N 65B01212-( ), 65B01430-3, or 65B01430-4, unless the outer cylinder has been inspected, reworked, and marked to indicate that Boeing Service Bulletin 747-32-2472, dated November 30, 2000, or Revision 1, dated February 23, 2006, has been accomplished. As of the effective date of this AD, no person may install an outer cylinder, P/N 65B01382-( ), of the wing landing gear on any airplane, unless the outer cylinder has been inspected, reworked, and marked to indicate that Boeing Service Bulletin 747-32-2472, Revision 1, dated February 23, 2006, has been accomplished.

Alternative Methods of Compliance (AMOCs)

(m)(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) 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, and the approval must specifically refer to this AD.

(4) AMOCs approved previously in accordance with AD 2004-16-05, amendment 39-13761, are approved as AMOCs for the corresponding provisions of paragraphs (f), (g), and (h) of this AD.

Issued in Renton, Washington, on June 13, 2006.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.