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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 2000-NM-330-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

      ( print page 10388)    

# 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, that currently requires repetitive inspections and torque checks of the hanger fittings and strut forward bulkhead of the forward engine mount and adjacent support structure, and corrective actions, if necessary. The existing AD also provides for optional terminating action for the repetitive inspections and checks. This action would mandate certain new repetitive torque checks and the previously optional terminating action. The actions specified by the proposed AD are intended to prevent loose fasteners and associated damage to the hanger fittings and bulkhead of the forward engine mount, which could result in separation of the engine from the airplane. 

# DATES:

Comments must be received by April 2, 2001. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-330-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 (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-330-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 2000-NM-330-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-330-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

                    On November 8, 2000, the FAA issued AD 2000-23-16, amendment 39-11988 (65 FR 69862, November 21, 2000), applicable to certain Boeing Model 747 series airplanes, to require repetitive inspections and torque checks of the hanger fittings and strut forward bulkhead of the forward engine mount and adjacent support structure, and corrective actions, if necessary. (On December 21, 2000, a correction to that AD was published in the                     **Federal Register**                     (65 FR 80301).) That action also provides for optional terminating action for the repetitive inspections and checks. That action was prompted by reports indicating the detection of loose fasteners of the hanger fittings and strut forward bulkhead of the forward engine mount. The requirements of that AD are intended to detect and correct loose fasteners and associated damage to the hanger fittings and bulkhead of the forward engine mount, which could result in separation of the engine from the airplane.                 

## Actions Since Issuance of Previous Rule 

In the preamble to AD 2000-23-16, the FAA indicated that the actions required by that AD were considered “interim action” and that it was considering a separate rulemaking action to mandate accomplishment of the terminating action described in Part 6 of Boeing Alert Service Bulletin 747-54A2203, dated August 31, 2000, which would terminate the repetitive inspections and checks required by that AD. The FAA also indicated that it was considering mandating the torque checks described in Part 3 of the alert service bulletin. 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 

The FAA previously reviewed and approved Boeing Alert Service Bulletin 747-54A2203, dated August 31, 2000, which describes procedures for repetitive detailed visual inspections and torque checks of the hanger fittings and strut forward bulkhead of the forward engine mount and adjacent support structure to detect loose fasteners, cracking, and/or damage; and corrective actions, if necessary. The corrective actions consist of a torque check, before further flight, if any loose fasteners are detected; rework of loose hanger fittings and damaged or cracked fittings that are within the allowable rework limits; and replacement if damage or cracks are detected that are outside the allowable rework limits. 

                    If certain damage of the strut forward bulkhead, bulkhead chords, lower spar web, or bulkhead channel is detected, the alert service bulletin specifies contacting Boeing for rework/replacement instructions. The alert service bulletin also describes procedures for a terminating action, which eliminates the need for the repetitive inspections and checks. The                           ( print page 10389)                        terminating action involves rework or replacement of the fittings.                 

## Explanation of Requirements of Proposed AD 

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 2000-23-16 to continue to require repetitive inspections and torque checks of the hanger fittings and strut forward bulkhead of the forward engine mount and adjacent support structure, and corrective actions, if necessary. This proposed AD would mandate certain new repetitive torque checks and the previously optional terminating action. The actions would be required to be accomplished in accordance with the alert service bulletin described previously, except as discussed below. 

## Differences Between Alert Service Bulletin and This Proposed AD 

Operators should note that, although the effectivity section of the alert service bulletin includes Boeing Model 747 series airplanes having serial numbers 21048 and 20887, these airplanes have been modified and are now powered by General Electric CF6-50 series engines, and are not affected by the actions required by this proposed rule. 

Operators also should note that, although the alert service bulletin specifies that the manufacturer may be contacted for certain rework and/or replacement instructions, this AD requires such rework and/or replacement to be done in accordance with a method approved by the 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 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 2000-23-16 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 inspections currently required by the existing AD on U.S. operators is estimated to be $55,200, or $480 per airplane, per inspection. 

The torque checks that are currently required by AD 2000-23-16 take approximately 24 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 torque checks currently required by the existing AD on U.S. operators is estimated to be $165,600, or $1,440 per airplane, per check. 

The new torque checks proposed in this AD action also would 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 this torque check on U.S. operators is estimated to be $55,200, or $480 per airplane, per check. 

The terminating action proposed in this AD action would take approximately 24 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts would cost approximately $300 per airplane. Based on these figures, the cost impact of the terminating action proposed by this AD on U.S. operators is estimated to be $200,100, or $1,740 per airplane. 

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the current or 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. 

§ 39.13 

2. Section 39.13 is amended by removing amendment 39-11988 (65 FR 80301, December 21, 2000), and by adding a new airworthiness directive (AD), to read as follows:

**Boeing:**                                 Docket 2000-NM-330-AD. Supersedes AD 2000-23-16, Amendment 39-11988.                             

*Applicability:*                                 Model 747 series airplanes, certificated in any category, as listed in Boeing Alert Service Bulletin 747-54A2203, dated August 31, 2000; except Model 747 series airplanes having serial numbers 21048 and 20887.                             

# 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 (d) 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 loose fasteners and associated damage to the hanger fittings and strut forward bulkhead of the forward engine mount, which could result in separation of the engine from the airplane, accomplish the following: 

## Restatement of Requirements of AD 2000-23-16 

### Repetitive Inspections/Checks 

                                (a) Within 60 days after December 6, 2000 (the effective date of AD 2000-23-16, amendment 39-11988): Perform a detailed visual inspection and torque check as                                       ( print page 10390)                                    specified in Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2203, dated August 31, 2000, to detect loose fasteners and associated damage to the hanger fittings and bulkhead of the forward engine mount, in accordance with Figure 1 of the alert service bulletin.                             

# 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.”

(1) If no loose fastener or associated damage is detected, repeat the inspections/checks thereafter at the applicable intervals specified in Figure 1 of the alert service bulletin until accomplishment of the terminating action specified in paragraph (c) of this AD. 

# Note 3:

Where there are differences between the AD and the alert service bulletin, the AD prevails.

### Corrective Actions 

(2) If any loose fastener or associated damage is detected, before further flight, perform the applicable corrective actions (torque check, rework or replacement of fittings), as specified in Figure 1 of the alert service bulletin. Repeat the inspections/checks thereafter at the applicable intervals specified in Figure 1 of the alert service bulletin until accomplishment of the terminating action specified in paragraph (c) of this AD. Where the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain corrective actions (rework or replacement of fittings), this AD requires such rework and/or replacement to be done 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 Manager's approval letter must specifically reference this AD. 

## New Requirements of This AD

### Repetitive Checks/Inspections/Corrective Actions 

(b) Within 18 months after the effective date of this AD: Do the torque check specified in Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2203, dated August 31, 2000, to detect loose fasteners of the hanger fittings of the forward engine mount. 

(1) If no loose fastener is detected, repeat the torque check thereafter at intervals not to exceed 1,200 flight cycles or 18 months, whichever occurs first, until accomplishment of the terminating action specified in paragraph (c) of this AD. 

(2) If any loose fastener is detected, before further flight, perform the applicable corrective actions as specified in Figure 4, Figure 5, or Part 6, as applicable, of the Accomplishment Instructions of the alert service bulletin. 

(i) If Figure 4 or Figure 5 of the Accomplishment Instructions of the alert service bulletin is used to do the corrective actions for the fitting; thereafter, repeat the detailed visual inspection required by paragraph (a) of this AD at the applicable intervals specified in Figure 1 of the alert service bulletin, and repeat the torque check for that fitting at intervals not to exceed 180 flight cycles. Accomplish the terminating action for that fitting as specified in Part 6 of the Accomplishment Instructions of the alert service bulletin within 18 months after finding any loose fastener or 60 months after the effective date of this AD, whichever occurs first. 

(ii) If Part 6 of the Accomplishment Instructions of the alert service bulletin is used to do the corrective actions for the fitting, this constitutes terminating action for the repetitive inspections/checks for that fitting only. 

(3) If any associated damage is found, before 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 Manager's approval letter must specifically reference this AD. If any damage to any fitting is found, before further flight, do the applicable corrective actions specified in Part 4 or Part 5 of the Accomplishment Instructions of the alert service bulletin; this constitutes terminating action for the repetitive inspections/checks for that fitting only. 

(4) If any loose fastener is detected during any repeat inspection/check specified in paragraph (b)(2)(i) of this AD, before further flight, accomplish the terminating action for that fitting as specified in Part 6 of the Accomplishment Instructions of the alert service bulletin. 

### Terminating Action 

(c) Within 60 months after the effective date of this AD: Accomplish all actions in the terminating action specified in Part 6 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2203, dated August 31, 2000. Accomplishment of this paragraph constitutes terminating action for the repetitive inspections/checks required by paragraphs (a) and (b) of this AD. Where the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain corrective actions (rework or replacement of fittings), this AD requires such rework and/or replacement to be done 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 Manager's approval letter must specifically reference this AD. 

# Note 4:

Installation of two BACW10BP*APU washers on Group A fasteners accomplished during modification in accordance with Boeing Service Bulletin 747-54A2159, dated November 3, 1994, Revision 1, dated June 1, 1995, or Revision 2, dated March 14, 1996; and pin or bolt protrusion as specified in the 747 Structural Repair Manual, Chapter 51-30-02 (both referenced in Boeing Alert Service Bulletin 747-54A2203, dated August 31, 2000); is considered acceptable for compliance with the terminating action specified in paragraph (c) of this AD.

## Alternative Methods of Compliance 

(d) 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 5:

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 

(e) 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 February 9, 2001. 

Vi L. Lipski, 

Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 01-3857 Filed 2-14-01; 8:45 am] 

BILLING CODE 4910-13-U