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Proposed Rule

Airworthiness Directives; Boeing Model 747 Series Airplanes Powered By Pratt & Whitney JT9D-7 Series Engines

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

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 series airplanes powered by Pratt & Whitney JT9D-7 series engines, that currently requires detailed visual inspections of the lugs on the bulkhead fitting of the rear engine mount, and corrective action, if necessary. The existing AD also specifies optional ultrasonic inspections, which, if accomplished, extend the repetitive interval for the required detailed visual inspections. This action would require accomplishment of the previously optional ultrasonic inspections and, for certain airplanes, rework of the bulkhead fitting of the rear engine mount. The actions specified by the proposed AD are intended to detect and correct bushing migration, corrosion, or cracking of the lugs on the bulkhead fitting of the rear engine mount, which could result in separation of the engine from the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by May 7, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-271-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. 2000-NM-271-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.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Tamara L. 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.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the Start Printed Page 15815proposed 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-271-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-271-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On August 25, 2000, the FAA issued AD 2000-18-01, amendment 39-11886 (65 FR 53161, September 1, 2000), applicable to certain Boeing Model 747 series airplanes powered by Pratt & Whitney JT9D-7 series engines, to require inspection of the lugs on the bulkhead fitting of the rear engine mount, and corrective action, if necessary. That action was prompted by a report of cracking of the inboard lug on the bulkhead fitting of the rear engine mount on the number 3 engine pylon on a Boeing Model 747-200B series airplane powered by Pratt & Whitney JT9D-7Q series engines. The requirements of that AD are intended to detect and correct bushing migration, corrosion, or cracking of the lugs on the bulkhead fitting of the rear engine mount, which could result in separation of the engine from the airplane.

Actions Since Issuance of Previous Rule

In the preamble to AD 2000-18-01, 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 repetitive ultrasonic inspections for cracking of the lugs on the bulkhead fitting of the rear engine mount, which were described in Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000 (which was referenced as the appropriate source of service information for the actions required by AD 2000-18-01). Those ultrasonic inspections were specified in AD 2000-18-01 as an option that, if accomplished, would extend the repetitive interval for the detailed visual and physical measurement inspections required by that AD. The FAA now has determined that further rulemaking action is indeed necessary, and this proposed AD follows from that determination.

Explanation of Relevant Service Information

Since the issuance of AD 2000-18-01, the FAA has reviewed and approved Boeing Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001. The procedures described in Revision 1 of the service bulletin for the inspections and interim rework are the same as those described in the original issue of the service bulletin. However, Part 5 of Revision 1 of the service bulletin includes new instructions for rework of the lugs on the bulkhead fitting of the rear engine mount. The rework procedures include a detailed visual inspection of the aft upper engine mount for damage; a Non-Destructive Testing inspection and repair of the aft upper engine mount, if necessary; and rework of the lugs, and installation of new bushings in the lug, on the bulkhead fitting of the rear engine mount. The service bulletin specifies that this rework is eventually necessary on any airplane on which bushing migration is found. This Part 5 rework is optional for airplanes on which no bushing migration, corrosion, or cracking is found; however, doing the rework per Part 5 of the service bulletin resets the compliance threshold for the repetitive detailed visual and ultrasonic inspections for cracking of the lugs on the bulkhead fitting of the rear engine mount. Accomplishment of the actions specified in Revision 1 of the service bulletin is intended to adequately address the identified unsafe condition.

Explanation of Change to Requirements of AD 2000-18-01

The requirements of AD 2000-18-01 are restated in this new proposed rule. References to Revision 1 of the service bulletin have been added to provide an additional source of service information for accomplishment of these existing requirements.

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 2000-18-01 to continue to require detailed visual inspections of the lugs on the bulkhead fitting of the rear engine mount, and corrective action, if necessary. The proposed AD would also require accomplishment of the previously optional ultrasonic inspections and, for certain airplanes, rework of the bulkhead fitting of the rear engine mount. The actions would be required to be accomplished per the service bulletin described previously, except as discussed below.

Differences Between Service Bulletin and This Proposed AD

Operators should note that, although the service bulletin specifies that the manufacturer may be contacted for certain repair instructions, this AD requires such repair to be done per a method approved by the 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 FAA to make such findings.

Cost Impact

There are approximately 200 airplanes of the affected design in the worldwide fleet. The FAA estimates that 47 airplanes of U.S. registry would be affected by this proposed AD.

The detailed visual inspections that are currently required by AD 2000-18-01 take approximately 8 work hours 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 on U.S. operators is estimated to be $22,560, or $480 per airplane, per inspection cycle.

The new inspections that are proposed in this AD action would take approximately 4 work hours per airplane to accomplish, at an average Start Printed Page 15816labor rate of $60 per work hour. Based on these figures, the cost impact of the new proposed requirements of this AD on U.S. operators is estimated to be $11,280, or $240 per airplane, per inspection cycle.

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.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

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:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

2. Section 39.13 is amended by removing amendment 39-11886 (65 FR 53161, September 1, 2000), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2000-NM-271-AD. Supersedes AD 2000-18-01, Amendment 39-11886.

Applicability: Model 747 series airplanes powered by Pratt & Whitney JT9D-7 series engines, as listed in Boeing Alert Service Bulletin 747-54A2200, dated July 7, 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 (h)(1) 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 bushing migration, corrosion, or cracking of the lugs on the bulkhead fitting of the rear engine mount, accomplish the following:

Restatement of Requirements of AD 2000-18-01:

Repetitive Detailed Visual Inspections

(a) At the later of the times in paragraphs (a)(1) and (a)(2) of this AD, perform a detailed visual inspection for bushing migration, corrosion, or cracking; and a physical measurement inspection using feeler gages for bushing migration; of the lugs on the bulkhead fitting of the rear engine mount, in accordance with Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, or Revision 1, dated February 15, 2001. Thereafter, repeat the inspection at intervals not to exceed 90 days, until the inspections required by paragraphs (c) and (d) of this AD have been accomplished.

(1) Prior to the accumulation of 10,000 total flight cycles, or within 15 years since the date of manufacture of the airplane, whichever occurs first.

(2) Within 90 days after September 18, 2000 (the effective date of AD 2000-18-01, amendment 39-11886).

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.”

Corrective Actions

(b) During any inspection accomplished in accordance with paragraph (a), (c), or (d) of this AD, if bushing migration, corrosion, or cracking is detected, accomplish paragraph (b)(1) or (b)(2) of this AD, as applicable.

(1) If light corrosion or bushing migration is found: Prior to further flight, do interim rework in accordance with Part 4 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, or Revision 1, dated February 15, 2001; EXCEPT where the service bulletin specifies to contact Boeing, 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 (DER) 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.

(2) If moderate to severe corrosion or any cracking is found: Prior to further flight, rework the lugs on the bulkhead fitting of the rear engine mount in accordance with Part 5 of Boeing Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001, except as provided by paragraph (g) of this AD; or in accordance with a method approved by the Manager, Seattle ACO; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company DER 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. Such rework resets the compliance threshold for the inspections per paragraphs (c) and (d) of this AD to 15 years or 10,000 flight cycles since rework, whichever is earlier.

New Requirements of This AD

Ultrasonic Inspection—Initial and Repetitive Inspections

(c) At the later of the times in paragraphs (c)(1) and (c)(2) of this AD, except as provided by paragraph (f) of this AD, perform an ultrasonic inspection to detect corrosion or cracking of the lugs on the bulkhead fitting of the rear engine mount, per Part 3 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, or Revision 1, dated February 15, 2001. Thereafter, repeat the ultrasonic inspection described in this paragraph at intervals not to exceed 1,400 flight cycles or 18 months, whichever occurs first.

(1) Prior to the accumulation of 10,000 total flight cycles, or within 15 years since the date of manufacture of the airplane, whichever occurs first.

(2) Within 9 months after the effective date of this AD. Start Printed Page 15817

Repetitive Detailed Visual and Physical Measurement Inspections

(d) After initial accomplishment of the inspections required by paragraph (c) of this AD, perform repetitive detailed visual inspections for bushing migration, corrosion, or cracking; and physical measurement inspections using feeler gages for bushing migration; of the lugs on the bulkhead fitting of the rear engine mount; per Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, or Revision 1, dated February 15, 2001. Perform the inspections at the interval stated in paragraph (d)(1) or (d)(2) of this AD, except as provided by paragraph (f) of this AD. Accomplishment of repetitive inspections per this paragraph constitutes terminating action for the inspections required by paragraph (a) of this AD.

(1) If no bushing migration is found during any inspection per this AD, the repetitive interval is not to exceed 1,400 flight cycles or 18 months, whichever occurs first.

(2) If any bushing migration is found during any inspection per this AD, the repetitive interval is not to exceed 180 days, until paragraph (e) of this AD has been done.

On-Condition Rework

(e) If any bushing migration is found during any inspection per this AD, within 30 months after finding the migrated bushing, or within 18 months after the effective date of this AD, whichever occurs later, do rework of the lugs on the bulkhead fitting of the rear engine mount (including a detailed visual inspection of the aft upper engine mount for damage; a Non-Destructive Testing inspection and repair of the aft upper engine mount, as applicable; and rework of the lugs, and installation of new bushings in the lug, on the bulkhead fitting of the rear engine mount) per Part 5 of Boeing Alert Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001. Such rework resets the compliance threshold for the inspections per paragraphs (c) and (d) of this AD to 15 years or 10,000 flight cycles since rework, whichever is earlier.

Optional Rework

(f) Rework of the lugs on the bulkhead fitting of the rear engine mount (including a detailed visual inspection of the aft upper engine mount for damage; a Non-Destructive Testing inspection and repair of the aft upper engine mount, as applicable; and rework of the lugs, and installation of new bushings in the lug, on the bulkhead fitting of the rear engine mount) per Part 5 of Boeing Alert Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001, resets the compliance threshold for the inspections per paragraphs (c) and (d) of this AD to 15 years or 10,000 flight cycles since rework, whichever is earlier.

Exception to Repair Requirement

(g) Where Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, or Revision 1, dated February 15, 2001, says to contact Boeing for repair instructions: Before further flight, repair per a method approved by the Manager, Seattle ACO, or per data meeting the type certification basis of the airplane approved by a Boeing Company DER 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.

Alternative Methods of Compliance

(h)(1) 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.

(2) Alternative methods of compliance, approved previously in accordance with AD 2000-18-01, Amendment 39-11886, are approved as alternative methods of compliance for corresponding actions in this AD.

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

(i) 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.

Start Signature

Issued in Renton, Washington, on March 14, 2001.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 01-6940 Filed 3-20-01; 8:45 am]

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