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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 97-NM-260-AD] 
          - RIN 2120-AA64 

# 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 777-200 series airplanes, that currently requires a one-time inspection to determine the serial numbers of various switch modules on the overhead panel and control stand, and replacement of switch modules with new, improved modules. The existing AD also requires repetitive tests of the cargo fire extinguishing system, and one-time tests of the fuel crossfeed valve, pack, trim air, and alternate flap control switches; and repair or replacement of switch modules with new improved modules, if necessary.

This action would revise the applicability of the existing AD. This action also would require replacement of the existing switch modules with new switch modules; replacement of the existing module assemblies with new module assemblies; or reworked module assemblies; as applicable. This proposal is prompted by the FAA's determination that certain switches are susceptible to contamination. The actions specified by the proposed AD are intended to minimize contamination of the switch contacts and consequent failure of the switches, which, if not corrected, could result in inability of the flight crew to activate the cargo fire extinguishing, fuel, air conditioning, and alternate flap systems. 

# DATES:

Comments must be received by July 14, 2000. 

# ADDRESSES:

                        Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 97-NM-260-AD, 1601 Lind Avenue, SW.,                               ( print page 34421)                            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.                     

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:

Mohamed Jamil, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2677; 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 notice may be changed in light of the comments received. 

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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 97-NM-260-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. 97-NM-260-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

On October 2, 1996, the FAA issued AD 96-20-01, amendment 39-9767 (61 FR 53035, dated October 10, 1996), applicable to certain Boeing Model 777-200 series airplanes, to require a one-time inspection to determine the serial numbers of various switch modules on the overhead panel and control stand, and replacement of switch modules with new, improved modules. This AD also requires repetitive tests of the cargo fire extinguishing system, and one-time tests of the fuel crossfeed valve, pack, trim air, and alternate flap control switches; and repair or replacement of switch modules with new improved modules, if necessary.

That action was prompted by a report indicating that the flight crew received a warning of fire in the forward cargo compartment during flight; later inspection revealed that the metered fire bottles failed to discharge possibly due to contamination in the arming switch of the cargo fire extinguishing system. The requirements of that AD are intended to minimize contamination of the switch contacts and consequent failure of the switches, which, if not corrected, could result in inability of the flight crew to activate the cargo fire extinguishing, fuel, air conditioning, and alternate flap systems. 

## Actions Since Issuance of Previous Rule

In the preamble to AD 96-20-01, the FAA specified that the actions required by that AD were considered to be interim action. The FAA indicated that it may consider further rulemaking to address other switches that may be susceptible to contamination. The FAA has determined that further rulemaking action is indeed necessary; this proposed AD follows from that determination.

Since the issuance of AD 96-20-01, the FAA has determined that certain switches, including the ten switches previously replaced in accordance with AD 96-20-01, are susceptible to the contamination as a result of particles originating from a component internal to the switches (as discussed in the preamble of AD 96-20-01). Such contamination could result in the failure of the switches and consequent inability of the flight crew to activate the cargo fire extinguishing, fuel, air conditioning, and alternate flap systems. In addition, analysis indicates that the functional tests required by AD 96-20-01 do not provide any additional increase in safety. Therefore, this proposed AD would eliminate the repetitive functional tests of the cargo fire extinguishing system previously required by AD 96-20-01. 

## Explanation of Relevant Service Information 

The FAA has reviewed and approved Boeing Alert Service Bulletin 777-31A0019, Revision 4, dated April 27, 2000, which describes procedures for replacing the switch modules in certain pushbutton switches in the flight compartment with new, improved switch modules. Operators would have the option of choosing one of the following methods for replacing the switch modules:
    - Method I: Replacement of the existing switch modules with new switch modules (including changing the part number of the reworked module assemblies and control stand assembly).
    - Method II: Replacement of the existing switch modules with new switch modules, and replacement of existing module assemblies with new module assemblies or reworked module assemblies (including changing the part number of the control stand assembly).

Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition. 

## 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 96-20-01 to require accomplishment of the actions specified in the service bulletin described previously. The proposed AD also would revise the applicability of the existing AD to include additional airplanes that are subject to the identified unsafe condition. 

## Explanation of Change Made to Applicability Statement 

                    Operators should note that the applicability of the proposal differs from the applicability of AD 96-20-01. The applicability has been revised to include additional airplanes (                    *i.e.,*                     line positions 41 through 85 inclusive) that are subject to the identified unsafe condition of this AD.                 

                    Operators also should note that the applicability of AD 96-20-01 identified the affected airplanes by “line positions.” The terminology “line positions” refers to airplane line numbers, rather than the manufacturer's tracking numbers for production airplanes. To clarify the affected airplanes, the applicability of this AD has been revised to identify those airplanes by “line numbers.”                           ( print page 34422)    

## Cost Impact 

There are approximately 85 airplanes of the affected design in the worldwide fleet. The FAA estimates that 23 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 20 work hours (for Method I) or 9 work hours (for Method II) per airplane to accomplish the proposed replacement, at an average labor rate of $60 per work hour. Required parts would cost approximately $12,785 per airplane. Based on these figures, the cost impact of the proposed requirements of this AD on U.S. operators is estimated to be $321,655, or $13,985 per airplane (for Method I), or $306,475, or $13,325 per airplane (for Method II). 

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. 

## Regulatory Impact 

The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. 

                    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 39-9767 (61 FR 53035, dated October 10, 1996), and by adding a new airworthiness directive (AD), to read as follows:

**Boeing:**                                 Docket 97-NM-260-AD. Supersedes AD 96-20-01, Amendment 39-9767.                            

*Applicability:*                                 Model 777-200 series airplanes, line numbers 1 through 85 inclusive, 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 (d)(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 minimize contamination of the switch contacts and consequent failure of the switches, which, if not corrected, could result in inability of the flight crew to activate the cargo fire extinguishing, fuel, air conditioning, and alternate flap systems, accomplish the following: 

## Replacement and Reidentification 

(a) For Groups 1 and 2 airplanes identified in Boeing Alert Service Bulletin 777-31A0019, Revision 4, dated April 27, 2000, except as provided in paragraph (b) of this AD, within 12 months after the effective date of this AD, perform the actions in either paragraph (a)(1) or (a)(2) of this AD. 

(1) Replace the existing switch modules with new switch modules (including changing the part number of the reworked module assemblies and control stand assembly) in accordance with Method I of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-31A0019, Revision 4, dated April 27, 2000. 

(2) Replace the existing switch modules with new switch modules, and replace the existing module assemblies with new module assemblies or reworked module assemblies (including changing the part number of the control stand assembly), in accordance with Method II of the Accomplishment Instructions of Boeing Alert Service Bulletin 777-31A0019, Revision 4, dated April 27, 2000.

# Note 2:

Replacements accomplished prior to the effective date of this AD in accordance with Boeing Alert Service Bulletin 777-31A0019, Initial Release, dated October 2, 1997; Revision 1, dated March 12, 1998; Revision 2, dated March 25, 1999; or Revision 3, dated January 27, 2000; are acceptable for compliance with the requirements of paragraphs (a)(1) and (a)(2) of this AD.

(b) For Group 2 airplanes identified in Boeing Alert Service Bulletin 777-31A0019, Revision 4, dated April 27, 2000, on which a guarded toggle passenger oxygen switch has been installed: Accomplishment of the actions specified in paragraphs (a)(1) and (a)(2) of this AD is not required for the passenger oxygen switch or window heat/emergency light module assembly. 

## Spares 

(c) As of the effective date of this AD, no person shall install on any airplane, any part listed in the “Existing Part Number” column of the table listed in paragraph II.D., “Existing Parts Accountability,” of Boeing Alert Service Bulletin 777-31A0019, Revision 4, dated April 27, 2000. 

## Alternative Methods of Compliance 

(d)(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 Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. 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 96-20-01, amendment 39-9767, are not considered to be approved as alternative methods of compliance with 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 

(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 May 23, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. 

[FR Doc. 00-13450 Filed 5-26-00; 8:45 am] 

BILLING CODE 4910-13-U