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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-90-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period. 

# SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9 series airplanes and C-9 airplanes, that would have required modification of the electrical power center and modification and overhaul of certain alternating current power relays. That proposal was prompted by reports indicating that the alternating current (AC) cross-tie relay shorted out internally, which caused severe smoke and burn damage to the relay, aircraft wiring, and adjacent panels. This new action revises the proposed rule by expanding the applicability to include additional airplanes; removing certain requirements; and revising certain requirements and service information. The actions specified by this new proposed AD are intended to prevent a short in the cross-tie relay, which may result in in-flight electrical fires. 

# DATES:

Comments must be received by July 9, 2001. 

# ADDRESSES:

                        Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-90-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                               ( print page 32277)                            “Docket No. 99-NM-90-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 Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Data and Service Management, Dept. C1-L5A (0800-0024); or Hamilton Sundstrand, Technical Publications, Mail Stop 302-9, Harrison Avenue, P.O. Box 7002, Rockford, IL 61125-7002. This information may be examined at the FAA, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California. 

# FOR FURTHER INFORMATION CONTACT:

Elvin Wheeler, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5344; fax (562) 627-5210. 

# 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. 

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 99-NM-90-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. 99-NM-90-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. 

## Discussion 

                    A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9 series airplanes and C-9 airplanes, was published as a notice of proposed rulemaking (NPRM) in the                     **Federal Register**                     on August 30, 1999 (64 FR 47149). That NPRM would have required modification of the electrical power center and modification and overhaul of certain alternating current (AC) power relays. That NPRM was prompted by reports indicating that the AC cross-tie relay shorted out internally, which caused severe smoke and burn damage to the relay, aircraft wiring, and adjacent panels. That condition, if not corrected, may result in in-flight electrical fires.                 

## Comments 

Due consideration has been given to the comments received in response to the NPRM. 

## Support for the NPRM 

Two commenters support the NPRM. 

## Existing AD With Same Requirements 

Two commenters request that the modification requirements of paragraph (a) of the NPRM supersede those of AD 89-07-08, amendment 39-6177 (54 FR 12589, March 28, 1989). One of the commenters also requests that a statement, “unless previously accomplished,” be added to paragraph (a) of the NPRM. The commenters state that the proposed modification duplicates the requirements of AD 89-07-08. One commenter states that the NPRM expands the effectivity of AD 89-07-08 to include airplane fuselage numbers up through 972. 

The FAA partially agrees. The commenters are correct that the modification (reference McDonnell Douglas DC-9 Service Bulletin 24-57, Revision 1, dated March 12, 1980) required by paragraph (a) of the NPRM is already required by AD 89-07-08. The commenter is incorrect that the effectivity of AD 89-07-08 was expanded in the NPRM; no additional airplane fuselage numbers were added. For these reasons, the FAA finds that the modification requirements of paragraph (a) of the NPRM are not necessary. We have deleted those requirements in the supplemental NPRM. 

## Wording of Unsafe Condition 

                    One commenter requests that the term “cross-tie relay” specified in the unsafe condition of the NPRM be revised to “AC power relay.” The commenter states that the unsafe condition should not single out one position of the affected AC power relays if the NPRM affects relays installed in any position (                    *i.e.,*                     cross-tie relays, generator relays, auxiliary power relays, and external power relays) as indicated in paragraph (a)(1) of the NPRM.                 

The FAA does not agree. In paragraph (a)(1) of the NPRM, the relay positions identified in the parenthetic are for clarification to identify the installed position of the relays. Most of the failures have occurred on the AC power relays installed in the cross-tie position. The six other relays (two each) at generators relays, auxiliary power relays, and external power relays are mounted in a vertical position; therefore, they are not as susceptible to the identified unsafe condition as the AC cross-tie relays. However, for interchangeability convenience, these six relays are modified to the P/N 914F567-4 configuration. 

## Incorrect Reference to Service Information 

                    One commenter requests that the phrase “in accordance with” in paragraph (a)(2) of the NPRM be deleted. Paragraph (a)(2) of the NPRM reads, “[r]eplace the Westinghouse alternating current power relays, P/N 914F567-3 or -4 with improved relays, P/N 9008D09 series, in accordance with McDonnell Douglas DC-9 Service Bulletin DC9-24-156, dated March 31, 1995.” The commenter states Service Bulletin DC9-24-156 recommends modifying the AC power relays per Sundstrand Aerospace Service Bulletin AVB79-24-2; however, the Sundstrand service bulletin only describes procedures for modification of AC power relays, part number (P/N)                           ( print page 32278)                        9008D09 series. The commenter also states that neither service bulletin addresses the modification or replacement of AC power relays, P/N 914F567-3 or -4.                 

The FAA agrees that neither McDonnell Douglas DC-9 Service Bulletin DC9-24-156, dated March 31, 1995, nor Sundstrand Aerospace Service Bulletin AVB79-24-2 describes procedures for doing the replacement required by paragraph (a)(2) of the NPRM. The correct source of service information for the required replacement is Chapter 24 of Boeing DC-9 or MD-80 Airplane Maintenance Manual (AMM), as applicable. In addition, we find that this replacement alone addresses the identified unsafe condition, and thus, the modification required by paragraph (a)(1) of the NPRM (reference Westinghouse Aerospace Service Bulletin 75-703, dated June 1977) is not necessary. We have revised paragraph (a) of the supplemental NPRM accordingly. 

One commenter requests that the overhaul required by paragraph (b) of the NPRM be required per the applicable original equipment manufacturer overhaul maintenance manual (OMM). The commenter states that Westinghouse Service Bulletin 76-703, dated June 1977 (which was referenced in paragraph (b) of the NPRM as the appropriate source of service information), describes procedures for modification of AC power relays, P/Ns 914F567-3 and -4, but does not include overhaul instructions for AC power relays, P/N 9008D09 series. 

The FAA agrees. For Sundstrand (Westinghouse) AC power relays, P/N 914F567-4, overhaul procedures are described in Chapter 24-20-46 of Westinghouse Overhaul Manual. For Sundstrand (Westinghouse) AC power relays, P/N 9008D09 series, overhaul procedures are described in Hamilton Sundstrand Component Maintenance Manual 24-20-87. We have revised paragraph (b) and added a new paragraph (c) of the supplemental NPRM accordingly. 

## Compliance Time of Overhaul 

Two commenters request that the compliance time specified in paragraphs (b)(1) and (b)(2) of the NPRM be revised. The commenters note the compliance times specified in those paragraphs do not take into consideration AC power relays that have been previously modified, installed as modified AC power relays, or exceeded the proposed overhaul limit. One commenter suggests to initially require the overhaul within 5,000 hours (or 4 years) after the effective date of the AD, or within 7,000 or 12,000 hours from the last overhaul or modification per paragraph (a) of the AD. The second commenter suggests that, for AC power relays previously installed, a compliance time of “prior to the accumulation of 7000 hours or 12000 hours (respectively) time since new or time since last overhaul and repeat at intervals not to exceed 7000 hours or 12000 hours (respectively).” 

The FAA agrees with the commenters that AC power relays modified or installed before the effective date of this AD can be overhauled within 7,000 or 12,000 flight hours (respectively) after that modification or installation, or within 30 days after the effective date of this AD, whichever occurs later. We have revised paragraphs (b) and (c) (previously designated as (b)(1) and (b)(2) in the NPRM, respectively) of the supplemental NPRM accordingly. In addition, we have added a new paragraph (d) to the supplemental NPRM to allow airplanes on which the flight hours since modification or installation of the AC power relay cannot be determined, to overhaul within 30 days after the effective date of this AD. 

One commenter requests that the FAA require a life limit of 6,000 flight hours on the affected AC power relays. The commenter believes that such a life limit would maintain an adequate level of safety for the affected fleet. The commenter states that it has deep concerns about the necessity of the NPRM. The commenter also states that “The [overhaul] costs to industry would be overwhelming and the profit to Sundstrand would be tremendous.” 

The FAA does not agree. We find that the replacement and repetitive overhauls required by this supplemental NPRM adequately address the identified unsafe condition. In addition, we find that the compliance times for completing the proposed actions to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety. No change to the supplemental NPRM is necessary with regards to this point. 

## Explanation of Change to Applicability Statement and Cost Impact 

The Westinghouse AC power relays on certain McDonnell Douglas Model DC-9-81, -82, -83, and -87 series airplanes, and Model MD-88 airplanes are identical to those on the affected Model DC-9 series airplanes and C-9 airplanes listed in the applicability of the original NPRM, and thus, may be subject to the identified unsafe condition of this supplemental NPRM. Therefore, the FAA has revised the applicability statement of the supplemental NPRM to include these additional airplanes. In addition, we have added the phrase “equipped with Westinghouse alternating current power relays, part number (P/N) 914F567-3” to exclude airplanes that have other relays. Furthermore, since “Model DC-9 series airplanes” includes Model C-9 airplanes, we have determined that listing Model C-9 airplanes in the applicability of this AD is not necessary. Therefore, we have removed any reference to “Model C-9 airplanes” from the supplemental NPRM. 

Based on the changes described above, the FAA has revised the Cost Impact section of the supplemental NPRM accordingly. 

## Conclusion 

Since these changes expand the scope of the originally proposed rule, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment. 

## Cost Impact 

There are approximately 1,150 McDonnell Douglas Model DC-9 series airplanes and Model MD-88 airplanes of the affected design in the worldwide fleet. The FAA estimates that 690 airplanes of U.S. registry would be affected by this proposed AD. 

It would take approximately 20 work hours per relay (7 relays per airplane) to accomplish the proposed replacement, at an average labor rate of $60 per work hour. Required parts would cost approximately $1,965 per relay. Based on these figures, the cost impact of the replacement proposed by this AD on U.S. operators is estimated to be $15,286,950, or $22,155 per airplane. 

It would take approximately 56 work hours per relay (7 relays per airplane) to accomplish the proposed overhaul, at an average labor rate of $60 per work hour. Required parts would cost approximately $1,965 per relay. Based on these figures, the cost impact of the overhaul proposed by this AD on U.S. operators is estimated to be $25,719,750, or $37,275, per airplane, per overhaul 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 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                           ( print page 32279)                        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 adding the following new airworthiness directive: 

**McDonnell Douglas:**                                 Docket 99-NM-90-AD.                             

*Applicability:*                                 Model DC-9 series airplanes and Model MD-88 airplanes, equipped with Westinghouse alternating current (AC) power relays, part number (P/N) 914F567-3; 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 (e) 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 a short in the cross-tie relay, which may result in in-flight electrical fires, accomplish the following: 

## Replacement 

(a) Within 12 months after the effective date of this AD, replace the Westinghouse AC power relays, P/N 914F567-3 (i.e., cross-tie relays, generator relays, auxiliary power relays, and external power relays), to a -4 configuration or with a Sundstrand (Westinghouse) relay, P/N 9008D09 series, per Chapter 24 of Boeing DC-9 or MD-80 Airplane Maintenance Manual (AMM), as applicable. 

## Repetitive Overhauls 

(b) For airplanes equipped with Sundstrand (Westinghouse) relay, P/N 914F567-4: Overhaul the relay per Chapter 24-20-46 of Westinghouse Overhaul Manual at the applicable time specified in paragraph (b)(1) or (b)(2) of this AD. Repeat the overhaul every 7,000 flight hours. 

(1) For AC power relays replaced per paragraph (a) of this AD: Overhaul within 7,000 flight hours after accomplishing that replacement. 

(2) For AC power relays modified or installed before the effective date of this AD: Overhaul within 7,000 flight hours after that modification or installation, or within 30 days after the effective date of this AD, whichever occurs later, except as provided by paragraph (d) of this AD. 

(c) For airplanes equipped with Sundstrand (Westinghouse) relay, P/N 9008D09 series: Overhaul the relay per Hamilton Sundstrand Component Maintenance Manual 24-20-87 at the applicable time specified in paragraph (c)(1) or (c)(2) of this AD. Repeat the overhaul every 12,000 flight hours. 

(1) For AC power relays replaced per paragraph (a) of this AD: Overhaul within 12,000 flight hours after accomplishing that replacement. 

(2) For AC power relays modified or installed before the effective date of this AD: Overhaul within 12,000 flight hours after that modification or installation, or within 30 days after the effective date of this AD, whichever occurs later, except as provided by paragraph (d) of this AD. 

(d) For airplanes on which the flight hours since modification or installation of the AC power relay cannot be determined: Overhaul within 30 days after the effective date of this AD. Repeat the overhaul at the times indicated in paragraph (b) or (c) of this AD, as applicable. 

## Alternative Methods of Compliance 

(e) 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, Los Angeles Aircraft Certification Office (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, Los Angeles ACO. 

# Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.

## Special Flight Permits 

(f) 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 June 7, 2001. 

Donald L. Riggin, 

Acting Manager,, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 01-14940 Filed 6-13-01; 8:45 am] 

BILLING CODE 4910-13-U