03-13388. Airworthiness Directives; Boeing Model 747 Series Airplanes Equipped With Pratt & Whitney JT9D-3 or JT9D-7 Series Engines (Except JT9D-70 Series Engines)

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 Boeing Model 747 series airplanes equipped with Pratt & Whitney JT9D-3 or JT9D-7 series engines (except JT9D-70 series engines). This proposal would require detailed inspections of the upper and lower surface of the forward lower spar of the nacelle strut for cracking or other damage, and for any loose or damaged fasteners. This proposal would also require replacement of loose or damaged fasteners and, if necessary, associated repair of the forward lower spar. This action is necessary to detect and correct cracking or other damage to the upper or lower surface of the forward lower spar and any loose or damaged fasteners, which could result in reduced structural capability of nacelle struts one through four, and possible separation of a strut and engine from the airplane during flight. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by July 14, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-27-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. 2002-NM-27-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 2002-NM-27-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. 2002-NM-27-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports of multiple loose and damaged fasteners and lower spar web damage of the No. 4 strut on two Boeing Model 747 series airplanes equipped with Pratt & Whitney JT9D-7 engines. This damage was observed at approximately 1,900 and 2,900 flight cycles after incorporation of the strut modification described in Boeing Alert Service Bulletin 747-54A2159, dated November 3, 1994. That modification was made mandatory by AD 95-10-16, amendment 39-9233 (60 FR 27008, May 22, 1995). Analysis by Boeing indicates that the loose fasteners were the result of incorrect installation of the fasteners or the collars. Multiple loose fasteners allow out-of-plane web deflection and damage to the lower spar web and fasteners. The resulting damage could cause cracking and the loss of the lower spar. This condition, if not corrected, could result in reduced structural capability of the strut, and possible separation of the strut and engine from the airplane during flight.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, including Evaluation Form, which describes procedures for the following actions:

Part 1: A detailed inspection of (a) the upper surface of the forward lower spar for cracking and fretting damage to the web, forward bulkhead channel, and stiffeners; and (b) the fasteners in that area for missing heads, damage, and evidence of looseness, such as cracked or broken sealant and fretting or galling around the collars, nuts, or fastener heads.

Part 2: A detailed inspection of (a) the lower surface of the forward lower spar for cracking and fretting damage to the web, c-channel, chords, and stiffener; and (b) the fasteners in that area for missing heads, damage, and evidence of looseness, such as cracked or broken sealant and fretting or galling around the collars, nuts, or fastener heads.

Part 3: Corrective action, which includes removing loose or damaged fasteners, examining the fastener holes for damage or cracks using a high frequency eddy current (HFEC) inspection, removing cracks or damage by oversizing the holes, ensuring that all cracks and damage are removed using a follow-up HFEC inspection, reaming the hole to a minimum size, and installing a new fastener.

Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, also specifies that, if damage or cracking is found which cannot be removed by oversizing a hole per the alert service bulletin, the Boeing Company should be contacted for additional instructions.

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 alert service bulletin described previously, except as discussed below.

Differences Between Alert Service Bulletin and Proposed AD

Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, specifies that the manufacturer is to be contacted for disposition of damage or cracks which cannot be repaired by oversizing a fastener hole per the alert service bulletin. The proposed AD, however, would require such repair to be accomplished per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), 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.

Another difference involves inspection of the upper surface and the lower surface of the forward lower spar. The alert service bulletin recommends inspection of the upper surface after accumulation of 300 flight cycles since modification of the strut in accordance with AD 95-10-16. Inspection of the lower surface is to be done after accumulation of 1,300 flight cycles since modification. This proposed AD, however, provides that, for airplanes which have accumulated 1,300 or more flight cycles since modification of the strut, the initial inspection may include both the upper surface and the lower surface of the forward lower spar. If no damage is detected, no further action is required by the AD.

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, that it would take from 20 to 64 work hours per airplane to accomplish the proposed inspections, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed inspections is estimated to be between $1,200 and $3,840 per airplane.

The cost impact figure discussed above is 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 2002-NM-27-AD.

Applicability: Model 747 series airplanes, equipped with Pratt & Whitney JT9D-3 or JT9D-7 series engines (excluding JT9D-70 series engines), as listed in Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001; 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 (g) 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 detect and correct cracking or other damage to the structure of the upper or lower surface of the forward lower spar and any loose or damaged fasteners, which could result in reduced structural capability of nacelle struts one through four, and possible separation of the strut and engine from the airplane during flight, accomplish the following:

Inspection of Upper Surface of Forward Lower Spar

(a) At the later of the times shown in paragraphs (a)(1) and (a)(2) of this AD: Perform a detailed inspection of the upper surface of the forward lower spar to detect cracks, fretting damage, and any loose or damaged fasteners, in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form.

(1) Within 500 flight cycles, but no sooner than 300 flight cycles, after modification of the strut in accordance with AD 95-10-16, amendment 39-2933.

(2) Within 6 months after the effective date of this AD; or

Note 2:

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 mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Inspection of Lower Surface of Forward Lower Spar

(b) If the detailed inspection required by paragraph (a) of this AD reveals any crack or fretting damage, or any loose or damaged fastener: Prior to further flight, perform a detailed inspection of the lower surface of the forward lower spar to detect cracks, fretting damage, and any loose or damaged fasteners, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form.

Follow-up Inspection

(c) If the detailed inspection of the upper surface of the forward lower spar required by paragraph (a) of this AD reveals no crack or fretting damage and no loose or damaged fastener: At the later of the times specified in paragraphs (c)(1) and (c)(2) of this AD, repeat the detailed inspection of the upper surface of the forward lower spar and perform a detailed inspection of the lower surface of the forward lower spar, in accordance with Parts 1 and 2, respectively, of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form.

(1) Within 1,500 flight cycles, but no sooner than 1,300 flight cycles, after modification of the strut, in accordance with AD 95-10-16; or

(2) Within 18 months after the effective date of this AD.

Optional Follow-Up Inspection

(d) If the detailed inspection of the upper surface of the forward lower spar required by paragraph (a) of this AD reveals no crack or fretting damage, and no loose or damaged fastener: Prior to further flight, the operator may elect to perform a detailed inspection of the lower surface of the forward lower spar to detect cracks, fretting damage, and any loose or damaged fasteners, in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form, provided that the airplane has accumulated at least 1,300 flight cycles since modification of the strut per AD 95-10-16.

Corrective Action

(e) If any detailed inspection described in paragraph (a), (b), (c), or (d) of this AD reveals any crack or fretting damage to the upper or lower surface of the forward lower spar or any loose or damaged fastener: Prior to further flight, accomplish the actions specified in paragraph (e)(1) or (e)(2) of this AD, as applicable.

(1) If the crack or fretting damage to the upper or lower surface of the forward lower spar falls within the parameters specified in Figure 4 or 5 (as applicable) of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form, and the airplane has accumulated 1,300 flight cycles or more since modification of the strut per AD 95-10-16: Remove any loose or damaged fasteners, repair any cracks or fretting damage to the upper or lower surface of the forward lower spar, and install new fasteners, in accordance with the Accomplishment Instructions of the service bulletin. No further action is required by this AD.

(2) If the crack or fretting damage to the upper or lower surface of the forward lower spar does not fall within the parameters specified in Figure 4 or 5 (as applicable) of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2209, dated November 8, 2001, excluding Evaluation Form, or if the airplane has accumulated fewer than 1,300 flight cycles since modification of the strut per AD 95-10-16: Accomplish additional repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), 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. For a repair method to be approved as required by this paragraph, the approval must specifically reference this AD.

(f) If the detailed inspection specified in paragraph (c) or (d) of this AD reveals no cracks or other damage to the upper or lower surface of the forward lower spar and no loose or damaged fasteners, no further action is required by this AD.

Alternative Methods of Compliance

(g) 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, 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 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

(h) Special flight permits may be issued in accordance with sections 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 May 22, 2003.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.