03-10514. Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 747 series airplanes. This proposal would require a one-time inspection to determine whether the outer cylinder of the wing landing gear has certain part numbers, and replacement of the outer cylinder of the wing landing gear with a new, improved, or reworked part if necessary. This proposal also would require removal of the load evening system, if such a system is installed. This action is necessary to prevent fracture of the outer cylinder of the wing landing gear, which could result in collapse of the wing landing gear. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by June 13, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-419-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-419-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Tamara Anderson, 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

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-419-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-419-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report indicating that the wing landing gear on a Boeing Model 747-300 series airplane collapsed while the airplane was turning onto a runway. Investigation revealed that the outer cylinder of the wing landing gear was fractured. We have received additional reports of air leaking from the wing landing gear, due to fracture of the outer cylinder, on certain Model 747 series airplanes. Fracture of the outer cylinder has been attributed to cracks caused by heat damage on the inner surface of the outer cylinder that resulted from machining at the top of the outer cylinder during production or overhaul. Chrome plating was applied at the top of the outer cylinder to be used by a piston in the load evening system that was installed on early Model 747 series airplanes. Later Model 747 series airplanes were not equipped with a load evening system because Boeing determined the system was unnecessary. However, certain airplanes not equipped with a load evening system were delivered with chrome plating on the outer cylinder. Cracking or heat damage of the outer cylinder of the wing landing gear, if not corrected, could lead to fracture of the outer cylinder of the wing landing gear, which could result in collapse of the wing landing gear.

The outer cylinder of the wing landing gear is interchangeable among all Model 747 series airplanes, except certain Model 747-400 series airplanes that are certificated to a maximum airplane taxi weight of 913 kilo-pounds (kips). Therefore, any Model 747 series airplane, except such Model 747-400 series airplanes, may have the subject outer cylinders installed and may be subject to the same unsafe condition.

Explanation of Relevant Service Information

We have reviewed and approved Boeing Service Bulletin 747-32-2472, dated November 30, 2000, which describes procedures for a one-time inspection to determine whether the outer cylinder of the wing landing gear has certain part numbers. For airplanes with the affected part numbers, the service bulletin recommends replacement of the existing outer cylinder with a new, improved, or reworked part. The procedures for rework, if accomplished, include the following:

• A nital etch inspection of the inner surface of the upper end of the outer cylinder for the presence of chrome plating.
• Removal of any chrome plating that is found.
• A magnetic particle inspection for cracking of the outer cylinder.
• A nital etch inspection for heat damage of the outer cylinder.
• Rework of the outer cylinder to remove any crack or heat damage.
• Changing the part number of the outer cylinder.

Accomplishment of the actions specified in Boeing Service Bulletin 747-32-2472 is intended to adequately address the identified unsafe condition.

Boeing Service Bulletin 747-32-2472 recommends accomplishment of Boeing Service Bulletin 747-32-2131 concurrently with the actions in Boeing Service Bulletin 747-32-2472. We have reviewed and approved Boeing Service Bulletin 747-32-2131, Revision 2, dated March 15, 1974, which describes procedures for removal of the load evening system installed on the wing landing gear.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service bulletins described previously.

Clarification of Applicability Statement

We stated previously that the outer cylinder of the wing landing gear is interchangeable among all Model 747 series airplanes, except certain Model 747-400 series airplanes certificated to a maximum airplane taxi weight of 913 kips. However, those airplanes do not have a separate model designation from other Model 747-400 series airplanes. Therefore, this proposed AD would apply to all Model 747 series airplanes.

Cost Impact

There are approximately 1,106 airplanes of the affected design in the worldwide fleet. We estimate that 256 airplanes of U.S. registry would be affected by this proposed AD. It would take approximately 1 work hour per airplane to accomplish the proposed inspection to determine whether subject part numbers are installed, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this proposed inspection on U.S. operators is estimated to be $15,360, or $60 per airplane.

We estimate that 225 airplanes in the worldwide fleet, and 66 airplanes of U.S. registry, are equipped with the subject outer cylinders that would require further action. It would take approximately 12 work hours per airplane to accomplish the proposed chrome removal and inspections for cracking or heat damage, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of these proposed actions on U.S. operators is estimated to be $47,520, or $720 per airplane.

For airplanes subject to removal of the load evening system, it would take approximately 240 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on the best data available, we estimate that necessary parts would cost $2,392. Based on these figures, the cost impact of the proposed removal of the load evening system is estimated to be $16,792 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new airworthiness directive:

Boeing: Docket 2000-NM-419-AD.

Applicability: All Model 747 series airplanes, certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent fracture of the outer cylinder of the wing landing gear, which could result in collapse of the wing landing gear, accomplish the following:

Inspection to Determine Part Number

(a) Within 36 months after the effective date of this AD, perform a one-time inspection to determine the part number 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, excluding Evaluation Form, dated November 30, 2000.

(1) If no outer cylinder having part number (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 (b) of this AD.

Replacement of Outer Cylinder

(b) For any outer cylinder identified in paragraph (a)(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 new, improved part or a part that has been inspected and reworked per the Accomplishment Instructions of Boeing Service Bulletin 747-32-2472, excluding Evaluation Form, dated November 30, 2000. 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 changing the part number of the outer cylinder.

Removal of the Load Evening System

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

Parts Installation

(d) As of the effective date of this AD, no person may install, on any airplane, an outer cylinder of the wing landing gear if the outer cylinder has P/N 65B01212-( ) (where “( )” is any dash number of that part number), 65B01430-3, or 65B01430-4.

Alternative Methods of Compliance

(e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(f) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on April 23, 2003.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.