Airworthiness Directives; Boeing Model 747-100, 747-200, 747-300, and 747SR Series Airplanes Powered by General Electric CF6-45/50 or Pratt & Whitney JT9D-70 Series Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 747-100, 747-200, 747-300, and 747SR series airplanes powered by General Electric CF6-45/50 or Pratt & Whitney JT9D-70 series engines, that currently requires a detailed visual inspection of the outboard diagonal brace for heat damage and cracking; and follow-on repetitive inspections and corrective actions, if necessary. This action proposes to require accomplishment of the previously optional replacement of any existing sealant with heat-resistant sealant as terminating action for the repetitive inspections required by this AD. This proposal is prompted by reports of heat damage to the forward end of the diagonal brace after accomplishment of a previous strut and wing modification. The actions specified by the proposed AD are intended to prevent heat damage to the diagonal brace, which could cause cracking, fracture, and possible loss of the diagonal brace load path and consequent separation of the strut and engine from the airplane.

DATES:

Comments must be received by October 19, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-124-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-124-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 (425) 227-2771; fax (425) 227-1181.

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 2001-NM-124-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. 2001-NM-124-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On June 4, 2001, the FAA issued AD 2001-12-05, amendment 39-12260 (66 FR 31527, June 12, 2001), applicable to certain Boeing Model 747-100, 747-200, 747-300, and 747SR series airplanes powered by General Electric CF6-45/50 or Pratt & Whitney JT9D-70 series engines, to require a detailed visual inspection of the outboard diagonal brace for heat damage and cracking; and follow-on repetitive inspections and corrective actions, if necessary. That action was prompted by reports of heat damage to the forward end of the diagonal brace after accomplishment of the modification of the nacelle strut and wing structure per AD 95-13-07, amendment 39-9287 (60 FR 33336, June 28, 1995).

Actions Since Issuance of Previous Rule

In the preamble to AD 2001-12-05, the FAA specified that the actions required by that AD were considered “interim action” and that the FAA was considering further rulemaking action to supersede that AD to require removal of the existing sealant and replacement with heat-resistant sealant, which would constitute terminating action for the repetitive inspections required by that AD action. The FAA now has determined that further rulemaking action is indeed necessary, and this proposed AD follows from that determination.

The FAA has determined that long-term continued operational safety will be better ensured by modifications or design changes to remove the source of the problem, rather than by repetitive inspections. Long-term inspections may not be providing the degree of safety assurance necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with numerous repetitive inspections, has led the FAA to consider placing less emphasis on special procedures and more emphasis on design improvements. The proposed corrective actions are consistent with these considerations.

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 supersede AD 2001-12-05 to continue to require a detailed visual inspection of the outboard diagonal brace for heat damage and cracking; and follow-on repetitive inspections and corrective actions, if necessary. This proposal would also require replacing any existing sealant with heat-resistant sealant, and either replacing or repairing the diagonal brace, if necessary, which constitutes terminating action for the repetitive inspections required by this proposed AD.

Difference Between the Proposed Rule and Service Bulletin

Operators should note that the service bulletin specifies that the diagonal brace may either be replaced per the service bulletin, or the manufacturer may be contacted for possible alternative rework (repair) instructions. However, paragraph (c)(2)(ii) of this proposed AD specifies that the repair be accomplished per a method approved by the Manager, Seattle Aircraft Certification Office, FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings.

Cost Impact

There are approximately 145 Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 39 airplanes of U.S. registry would be affected by this proposed AD.

The repetitive inspections that are currently required by AD 2001-12-05 take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions is estimated to be $2,340 per airplane, per inspection cycle.

The terminating action that is proposed in this AD action would take approximately 2 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts would cost approximately $100 per airplane. Based on these figures, the cost impact of the proposed requirements of this AD is estimated to be $8,580, or $220 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 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.