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Proposed Rule

Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP Series Airplanes

Action

Notice Of Proposed Rulemaking (Nprm).

Summary

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. The existing AD currently requires repetitive detailed and ultrasonic inspections of the thrust links of the rear engine mounts for any crack or fracture and corrective actions if necessary. This proposed AD would require repetitive replacement of the thrust links with new or overhauled thrust links, which ends the repetitive detailed and ultrasonic inspections. This proposed AD results from the finding of fractured and cracked forward lugs of the rear engine mount thrust link on the number one strut on two airplanes. We are proposing this AD to prevent cracked or fractured thrust links that could lead to the loss of the load path for the rear engine mount bulkhead and damage to other primary engine mount structure, which could result in the in-flight separation of the engine from the airplane and consequent loss of control of the airplane.

Unified Agenda

Airworthiness Directives

1 action from November 2013

  • November 2013
    • Actions Will Continue Through
 

Table of Contents Back to Top

Tables Back to Top

DATES: Back to Top

We must receive comments on this proposed AD by February 27, 2006.

ADDRESSES: Back to Top

Use one of the following addresses to submit comments on this proposed AD.

  • DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
  • Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
  • Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.
  • Fax: (202) 493-2251.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT: Back to Top

Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6437; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: Back to Top

Comments Invited Back to Top

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “Docket No. FAA-2005-23441; Directorate Identifier 2005-NM-199-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or can visit http://dms.dot.gov.

Examining the Docket Back to Top

You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion Back to Top

On September 6, 2005, we issued AD 2005-19-06, amendment 39-14271 (70 FR 54474, September 15, 2005), for certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. (A correction to AD 2005-19-06 was published in the Federal Register on September 30, 2005 (70 FR 57124).) That AD requires repetitive detailed and ultrasonic inspections of the thrust links of the rear engine mounts for any crack or fracture and corrective actions if necessary. That AD resulted from the finding of a fractured forward lug of the rear engine mount thrust link on the number one strut. We issued that AD to detect and correct cracked or fractured thrust links that could lead to the loss of the load path for the rear engine mount bulkhead and damage to other primary engine mount structure, which could result in the in-flight separation of the engine from the airplane and consequent loss of control of the airplane.

Actions Since Existing AD Was Issued Back to Top

In the preamble to AD 2005-19-06, we indicated that the actions required by that AD were considered “interim action.” We also indicated that we were considering further rulemaking action to require repetitive replacement of the thrust link with a new or overhauled thrust link. (The repetitive replacements are included as an optional terminating action in AD 2005-19-06.) However, the planned compliance time for that action was sufficiently long so that it was practicable to allow notice and opportunity for prior public comment. We have now determined that further rulemaking making action is indeed necessary, and this NPRM follows from that determination. We point out that this NPRM would require the repetitive replacements within a certain compliance time, regardless of any inspection results.

Comments Back to Top

We have considered the following comments to AD 2005-19-06.

Request To Use an Alternative Method of Compliance (AMOC) Back to Top

One commenter states that it can reduce the work required for replacing a thrust link by omitting the step for removing the engine to gain access to the thrust link. Part 2 of the accomplishment instructions of Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005, specifies removal of the engine. The commenter states, however, that there is no load on the thrust link at static condition, so the engine does not need to be removed. Instead, only the engine exhaust sleeve needs to be removed to replace the thrust link. The commenter also states that, in Boeing message No. 1-385158991-9, dated September 16, 2005, the manufacturer agreed that removing the sleeve would be an appropriate alternative procedure for replacing the thrust link. On October 26, 2005, the commenter submitted this request for approval as an AMOC.

We agree, since we have found the commenter's request for an AMOC to be acceptable. We have approved removing the side cowls, as an alternative to opening the side cowls as required by paragraph (g) of AD 2005-19-06. We have also approved removal of the turbine exhaust sleeve, as an alternative to removing the engine as required by paragraph (j) of AD 2005-19-06 (corresponding to paragraph (k) of this NPRM) provided that the engine is supported. We have included a provision in paragraph (l)(5) of this NPRM to account for the commenter's AMOC. Under the provisions of paragraph (l) of this NPRM, we may consider other requests for approval of an alternative method of compliance if sufficient data are submitted to substantiate that such a method would provide an acceptable level of safety.

Request To Clarify Inspection Requirements Back to Top

One commenter requests that we clarify the required actions of AD 2005-19-06 for thrust links having part number (P/N) 65B90360-7. The commenter states that Boeing Alert Service Bulletin 747-71A2309 requires repetitive replacement of those thrust links, but that the repetitive replacement is identified as an optional action in AD 2005-19-06. The commenter would like to know if this means that there is no mandatory requirement for thrust links having P/N 65B90360-7.

As discussed previously, repetitive replacement of the thrust links as required by AD 2005-19-06 is considered an optional action because the planned compliance time for that action was sufficiently long enough to allow the public time to comment. This NPRM, however, would require the repetitive replacement of thrust links having P/N 65B90360-7 in agreement with the service bulletin. Also, we point out that AD 2005-19-06 does require the repetitive replacement of P/N 65B90360-7. Although that action is conditional in AD 2005-19-06, depending on whether P/N 65B90360-7 was installed while accomplishing the corrective action as applicable or the optional terminating action, as specified in paragraphs (h)(1)(ii) and (j)(2) of AD 2005-19-06, respectively.

Clarification of AMOC Paragraph Back to Top

We have revised this action to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies.

FAA's Determination and Requirements of the Proposed AD Back to Top

We have evaluated all pertinent information and identified an unsafe condition that is likely to develop on other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 2005-19-06. This proposed AD would continue to require repetitive detailed and ultrasonic inspections of the thrust links of the rear engine mounts for any crack or fracture and corrective actions if necessary. This proposed AD would also require repetitive replacement of the thrust links with new or overhauled thrust links, which would end the repetitive inspections.

Costs of Compliance Back to Top

There are about 274 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs, at an average labor rate of $65 per hour, for U.S. operators to comply with this proposed AD.

Estimated Costs Back to Top
Action Work hours Parts Cost per airplane Number of U.S.-registered airplanes Fleet cost
Inspection (required by AD 2005-19-06) 8 (2 per engine) None $520, per inspection cycle 100 $52,000, per inspection cycle.
Replacement (new proposed action) 4 (1 per engine) $41,424 $41,684, per replacement cycle 100 $4,168,400, per replacement cycle.

Authority for This Rulemaking Back to Top

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings Back to Top

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39 Back to Top

The Proposed Amendment Back to Top

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

begin regulatory text

PART 39—AIRWORTHINESS DIRECTIVES Back to Top

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. The Federal Aviation Administration (FAA) amends § 39.13 by removing amendment 39-14271 (70 FR 54474, September 15, 2005), corrected at 70 FR 57124, September 30, 2005, and by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2005-23441; Directorate Identifier 2005-NM-199-AD.

Comments Due Date Back to Top

(a) The FAA must receive comments on this AD action by February 27, 2006.

Affected ADs Back to Top

(b) This AD supersedes AD 2005-19-06.

Applicability Back to Top

(c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes, certificated in any category; equipped with Pratt Whitney JT9D-3 and -7 series engines, except JT9D-70 engines; as identified in Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005.

Unsafe Condition Back to Top

(d) This AD results from the finding of fractured and cracked forward lugs of the rear engine mount thrust link on the number one strut on two airplanes. We are issuing this AD to prevent cracked or fractured thrust links that could lead to the loss of the load path for the rear engine mount bulkhead and damage to other primary engine mount structure, which could result in the in-flight separation of the engine from the airplane and consequent loss of control of the airplane.

Compliance Back to Top

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Restatement of Requirements of AD 2005-19-06 Back to Top

Service Bulletin References

(f) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005.

Repetitive Inspections of Thrust Links

(g) Within 90 days after September 30, 2005 (the effective date of AD 2005-19-06), do a detailed inspection and ultrasonic inspection of thrust link lugs having part number (P/N) 65B90360-1 or -4 of the rear engine mount of struts 1, 2, 3, and 4 for any crack or fracture, in accordance with part 1 of the service bulletin. If the thrust link is not found cracked or fractured: Repeat the inspections thereafter at intervals not to exceed 1,200 flight cycles or 18 months, whichever is first, until the repetitive replacement or overhaul of the thrust link required by paragraph (k) of this AD is accomplished. Accomplishing the repetitive replacement or overhaul of a thrust link as specified in paragraph (h) or (k) of this AD terminates the repetitive inspections for that thrust link only.

Corrective Actions

(h) If a cracked thrust link is found during any inspection required by paragraph (g) of this AD or during any replacement or overhaul done in accordance with the service bulletin: Before further flight, do the actions specified in paragraph (h)(1) of this AD. If a fractured thrust link is found during any inspection required by paragraph (g) of this AD or during any replacement or overhaul done in accordance with the service bulletin: Before further flight, do the actions specified in paragraphs (h)(1) and (h)(2) of this AD.

(1) Replace the thrust link with a new or overhauled thrust link in accordance with part 2 of the service bulletin; except as provided by paragraph (i) of this AD. Repeat the replacement at the applicable compliance time specified in paragraph (h)(1)(i) or (h)(1)(ii) of this AD.

(i) For replacement with a thrust link assembly having P/N 65B90360-1 or -4: Thereafter at intervals not to exceed 6,000 flight cycles.

(ii) For replacement with a thrust link assembly having P/N 65B90360-7: Thereafter at intervals not to exceed 12,000 flight cycles.

(2) Do the corrective actions in accordance with Parts 3, 4, and 5 of the service bulletin; except as provided by paragraph (i) of this AD.

Exception to Service Bulletin

(i) Where the service bulletin specifies to contact Boeing for appropriate action, do the corrective action using a method approved in accordance with paragraph (m) of this AD.

Credit for Certain Corrective Actions

(j) Reworking the lugs on the bulkhead fitting of the rear engine mount as specified in paragraphs (b)(2), (e), and (f) of AD 2001-15-15, amendment 39-12349, is acceptable for compliance with accomplishing the corrective action specified in “Part 3—Rear Engine Mount Bulkhead Inspection and Lug Overhaul and Upper Fitting Overhaul and Bolt Replacement” of the service bulletin.

New Requirements of This AD Back to Top

Terminating Action—Repetitive Replacement or Overhaul of All Thrust Links

(k) At the applicable compliance times specified in Table 1 of this AD: Repetitively replace the thrust link of the rear engine mount of struts 1, 2, 3, and 4 with a new or overhauled thrust link, in accordance with part 2 of the service bulletin; except as provided by paragraph (i) of this AD. During any replacement required by this paragraph, an existing thrust link may be replaced with a new or overhauled thrust link having P/N 65B90360-1, -4 or -7, provided that the applicable repetitive interval specified in Table 1 of this AD is complied with. If a fractured thrust link is found during any replacement or overhaul done in accordance with this paragraph: Before further flight, do the corrective actions specified in paragraph (h)(2) of this AD. Repetitive replacement of all thrust links having P/N 65B90360-1 or -4 terminates the repetitive inspections required by paragraph (g) of this AD. Accomplishing the repetitive replacement or overhaul of a thrust link required by paragraph (h) of this AD constitutes compliance with the requirements of this paragraph for that thrust link only.

Table 1.—Compliance Times Back to Top
For thrust link P/N— Initial replacement— Repetitive interval—
65B90360-1 or -4 Within 36 months after the effective date of this AD Thereafter at intervals not to exceed 6,000 flight cycles.
65B90360-7 Within 12,000 flight cycles after the new thrust link has been installed Thereafter at intervals not to exceed 12,000 flight cycles.

Alternative Methods of Compliance (AMOCs)

(l)(1) The Manager, Seattle Aircraft Certification Office (ACO), Transport Airplane Directorate, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

(4) The actions identified in paragraphs (g) and (k) of this AD are approved as an AMOC to paragraphs (c) and (d) of AD 2004-07-22, amendment 39-13566, for the inspections of structural significant item S-2, for the thrust links only, of Boeing Supplemental Structural Inspection Document D6-35022, Revision G, dated December 2000. All provisions of AD 2004-07-22 that are not specifically referenced in this paragraph, including the initial inspection threshold required by paragraph (d) of AD 2004-07-22, remain fully applicable and must be complied with.

(5) AMOCs approved previously in accordance with AD 2005-19-06, amendment 39-14271, are approved as AMOCs for the corresponding provisions of this AD.

Issued in Renton, Washington, on December 23, 2005.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

end regulatory text

[FR Doc. E6-136 Filed 1-10-06; 8:45 am]

BILLING CODE 4910-13-P

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