AD 97-21-15 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to all British Aerospace Model Avro 146-RJ series airplanes, that requires a modification of the electrical system in the equipment bay area by replacing certain cables, clamps, and fairleads with new components. This amendment is prompted by a report indicating that the incorrect size of electrical cables were used in the generator feeder circuit to certain busbars from the generator contactors. As a result, the electrical cables are not compatible with generator rating requirements and can overheat. The actions specified by this AD are intended to prevent possible overheating of electrical generator feeder cables and consequent damage, which could lead to possible fire or the loss of essential electrical systems.

Final rule

97-21-15 BRITISH AEROSPACE REGIONAL AIRCRAFT (Formerly British Aerospace Regional Aircraft Limited, Avro International Aerospace Division; British Aerospace, PLC; British Aerospace Commercial Aircraft Limited): Amendment 39-10168. Docket 97-NM-05-AD.
Applicability: All Model Avro 146-RJ series airplanes, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (b) 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 conditionhas not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent possible overheating of the electrical generator feeder cables and consequent damage, which could lead to possible fire or loss of essential electrical systems, accomplish the following:

(a) Prior to the accumulation of 500 flight cycles after the effective date of this AD, modify the electrical system in the electrical equipment bay in accordance with British Aerospace Service Bulletin SB.24-113-01532A, dated March 12, 1996, or British Aerospace Service Bulletin SB.24-113-01532A, Revision 1, dated June 18, 1996.

(b) 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, Standardization Branch, ANM-113, 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, Standardization Branch, ANM-113.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(c) 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.

(d) The modification shall be done in accordance with British Aerospace Service Bulletin SB.24-113-01532A, dated March 12, 1996; or British Aerospace Service Bulletin SB.24-113- 01532A, Revision 1, dated June 18, 1996, which contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date
Shown on Page

1, 2
1
June 18, 1996
3-15
Original
March 12, 1996

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from AI(R) American Support, Inc., 13850 McLearen Road, Herndon, Virginia 20171. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in British airworthiness directive 006-03-96, dated March 12, 1996.

(e) This amendment becomes effective on November 24, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to all British Aerospace Model Avro 146-RJ series airplanes was published in the Federal Register on February 28, 1997 (62 FR 9111). That action proposed to require modifying the electrical system in the equipment bay area by replacing certain cables, clamps, and fairleads with new components. Consideration of Comment Received

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the one comment received. Request to Revise the Summary Section of the Preamble of the Proposed AD

The commenter requests that the description of what prompted the NPRM that appeared in the Summary section of the preamble to the NPRM be revised to read, " . . the generator feeder circuit to certain busbars from the generator contactors. As a result, the cables are not compatible . . . ." The commenter suggests that this statement is more accurate. The FAA acknowledges that the commenter's wording is more accurate and has revised the final rule to reflect the suggested changes. In addition, the FAA has included the word "electrical" to identify which type of cables are not compatible. Request to Revise Other Sections of the Preamble of the Proposed AD

The commenter also requests that the description of what the CAA advises that appeared in the Discussion section of the preamble to the NPRM be revised to read, ". . . generator feeder circuit to busbars AC1 and AC2."

In addition, the commenter requests that a description of the procedures referenced in the service bulletin that appeared in the Explanation of Relevant Service Information section of the preamble to the NPRM be revised to read ". . . existing 6ANC generator feeder cables installed to the AC1 and AC2 busbars from the generator contactors . . . ."

The commenter states that these statements will improve the technical accuracy of the proposal. The FAA recognizes that the suggested changes to these sections provide improved technical accuracy. However, since neither the Discussion nor the Explanation of Relevant Service Information sections of the preamble to the NPRM are restated in the final rule, no change to the final rule is necessary. Explanation of Changes Made to the Proposal

For clarification purposes, the FAA has revised the description of the unsafe condition that appeared throughout the NPRM to read, ". . . possible overheating of the electrical generator feeder cables and consequent damage, which could lead to a possible fire or the loss of essential electrical systems."

The FAA also has revised the final rule to reflect the corporate name change of British Aerospace Regional Aircraft Limited, Avro International Aerospace Division to British Aerospace Regional Aircraft. In addition, the address for obtainingservice information has been revised to AI(R) American Support, Inc., 13850 McLearen Road, Herndon, Virginia 20171.

Furthermore, the FAA has revised the area code from (206) to (425) of the telephone numbers in the For Further Information Contact section of the final rule. Conclusion

After careful review of the available data, including the comment noted above, the FAA has determined
that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. Cost Impact

The FAA estimates that 10 British Aerospace Model Avro 146-RJ series airplanes of U.S. registry will be affected by this AD. Modification of the electrical system will take approximately 4 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $300 per airplane.Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $5,400, or $540 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the 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 adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule"under 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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 - [Amended]
2. Section 39.13is amended by adding the following new airworthiness directive:

The service information referenced in this AD may be obtained from AI(R) American
Support, Inc., 13850 McLearen Road, Herndon, Virginia 20171. This information may be examined
at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601
Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol
Street, NW., suite 700, Washington, DC.

Tim H. Backman, Aerospace Engineer, Standardization
Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-2797; fax (425) 227-1149.