00-32576. Airworthiness Directives; Boeing Model 747-100, 747-200, 747-300, 747SP, and 747SR Series Airplanes Powered by Pratt & Whitney JT9D-3 and JT9D-7 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, 747SP, and 747SR series airplanes powered by Pratt & Whitney JT9D-3 or JT9D-7 series engines. That AD currently requires inspections of the vertical chords of the aft torque bulkhead of the outboard nacelle struts, and corrective action, if necessary. That AD also gives an optional modification of the vertical chords, which ends the inspections. This action would require the previously optional modification. The actions specified by the proposed AD are intended to prevent cracking of the vertical chords adjacent to the lower spar fitting, which could result in separation of the diagonal brace load path. Continued operation with a separated diagonal brace load path increases loads on the upper link, midspar fitting, and dual side links, which could result in separation of the strut and engine from the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by February 5, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-354-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 [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-M-354-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-354-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-354-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On November 14, 2000, the FAA issued AD 2000-23-25, amendment 39-11998 (65 FR 70781, November 28, 2000), applicable to certain Boeing Model 747-100, 747-200, 747-300, 747SP, and 747SR series airplanes powered by Pratt & Whitney JT9D-3 or JT9D-7 series engines; to require inspections of the vertical chords of the aft torque bulkhead of the outboard nacelle struts, and corrective action, if necessary. That AD also gives optional terminating action for the inspections. That action was prompted by reports of fatigue cracking of the vertical chords of the aft torque bulkhead of the outboard nacelle struts. The requirements of that AD are intended to detect and correct cracking of the vertical chords adjacent to the lower spar fitting, which could result in separation of the diagonal brace load path. Continued operation with a separated diagonal brace load path increases loads on the upper link, midspar fitting, and dual side links, which could result in separation of the strut and engine from the airplane.

Actions Since Issuance of Previous Rule

In the preamble to AD 2000-23-25, the FAA indicated that the actions required by that AD were considered “interim action” and that further rulemaking action was being considered to require the modification of the vertical chords of the aft torque bulkhead of the outboard nacelle struts in Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000, which AD 2000-23-25 references as optional terminating action. The FAA has determined that further rulemaking is needed, and this proposed AD follows from that determination.

Explanation of Change Made to Requirements of Existing AD

The FAA has added a note to this proposed rule to clarify the definition of a detailed visual inspection, as specified in paragraph (a)(1) of this AD.

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 2000-23-25 to continue to require inspections of the vertical chords of the aft torque bulkhead of the outboard nacelle struts, and corrective action, if necessary. The proposed AD would also require modification of the vertical chords, which would end the inspections. The actions would be required to be accomplished in accordance with Boeing Alert Service Bulletin 747-54A2201, which was described in AD 2000-23-25, except as discussed below.

Difference Between Service Bulletin and This Proposed AD

Operators should note that, although the service bulletin says to contact the manufacturer for certain repairs, this proposed AD would require those repairs to be accomplished by a method approved by the FAA, or according to data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative authorized by the FAA to make such findings.

Cost Impact

There are approximately 366 airplanes of the affected design in the worldwide fleet. The FAA estimates that 115 airplanes of U.S. registry would be affected by this proposed AD.

The detailed visual inspections that are currently required by AD 2000-23-25 take approximately 18 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the FAA estimates that the cost impact of these inspections on U.S. operators is $124,200, or $1,080 per airplane, per inspection cycle.

The ultrasonic and eddy current inspections that are currently required by AD 2000-23-25 take approximately 18 work hours per airplane, at an average labor rate of $60 per work hour. Based on these figures, the FAA estimates that the cost impact of these inspections on U.S. operators is $124,200, or $1,080 per airplane, per inspection cycle.

The new modification that is proposed in this AD action would take approximately 48 work hours per airplane, at an average labor rate of $60 per work hour. Required parts would cost approximately $10,000 per airplane. Based on these figures, the FAA estimates that the cost impact of the proposed modification on U.S. operators is $1,481,200, or $12,880 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 removing amendment 39-11998 (65 FR 70781, November 28, 2000), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2000-NM-354-AD. Supersedes AD 2000-23-25, Amendment 39-11998.

Applicability: Model 747-100, 747-200, 747-300, 747SP, and 747SR series airplanes powered by Pratt & Whitney JT9D-3 or JT9D-7 series engines; as listed in Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000; 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 cracking of the vertical chords adjacent to the lower spar fitting, which could result in separation of the diagonal brace load path and lead to separation of the strut and engine from the airplane, accomplish the following:

Restatement of Requirements of AD 2000-23-25:

Inspections

(a) Except as provided by paragraph (b) of this AD, prior to the accumulation of 14,000 total flight cycles, or within 90 days after December 13, 2000 (the effective date of AD 2000-23-25), whichever occurs later: Accomplish paragraphs (a)(1) and (a)(2) of this AD.

(1) Perform a detailed visual inspection to detect cracking of the vertical chords of the aft torque bulkhead of the outboard nacelle struts, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000. Thereafter, repeat this inspection at intervals not to exceed 600 flight cycles until paragraph (d) of this AD is accomplished.

(2) Perform surface eddy current and ultrasonic inspections to detect cracking of the vertical chords of the aft torque bulkhead of the outboard nacelle struts, in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000. Thereafter, repeat these inspections at intervals not to exceed 1,200 flight cycles until paragraph (d) of this AD is accomplished.

Note 2:

For the purposes of this AD, a detailed visual 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 mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Optional Compliance Time

(b) If Boeing Service Letter 747-54-055, dated April 24, 1998, was accomplished on the airplane during the modification of the nacelle strut in accordance with AD 95-10-16, amendment 39-9233: Accomplishment of the initial inspection in paragraph (a) of this AD may be deferred until 3,000 flight cycles after accomplishment of the service letter.

Repair

(c) If any cracking is detected during any inspection or modification required by this AD: Prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with 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. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD.

New Requirements of This Ad

Modification (Terminating Action)

(d) Within 4 years after the effective date of this AD, do the modification of the vertical chords of the aft torque bulkhead of the outboard nacelle struts according to Part 4 of Boeing Alert Service Bulletin 747-54A2201, dated September 28, 2000. After this modification, stop the repetitive inspections required by paragraph (a) of this AD.

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 ACO. 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 3:

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 December 15, 2000.

Dorenda D. Baker,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.