AD 97-16-04

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes, that currently requires inspections to detect improper connections of the wire harness installation to the cartridges of the fire extinguishers in the engine nacelles, correction of any discrepancy, and modification of the wiring. This amendment adds a revised modification of that wiring, which, if accomplished, would terminate the inspections currently required by the existing AD. This amendment is prompted by reports indicating that, due to the removal of a certain clamp during maintenance, these fire extinguisher cartridges still could be connected incorrectly after the modification required by the existing AD has been accomplished. The actions specified by this AD are intended to prevent incorrect wiring of the cartridges, which would result in inability of the fire extinguishers to jointly discharge extinguishing agent into anacelle in the event of an engine fire.

Final rule

97-16-04 SAAB AIRCRAFT AB: Amendment 39-10095. Docket 96-NM-130-AD. Supersedes AD 94-03-06, Amendment 39-8813.
Applicability: Model SAAB SF340A series airplanes having serial numbers 004 through 159 inclusive; and Model SAAB 340B series airplanes having serial numbers 160 through 345 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 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 (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 notbeen eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent incorrect wiring of the wire harness installation to the fire extinguisher cartridges in the engine nacelles, which would result in the inability of the fire extinguishers to jointly discharge agent into a nacelle in the event of a fire, accomplish the following:

(a) Within 25 days after February 16, 1994 (the effective date of AD 94-03-06, amendment 39-8813), perform an inspection to ensure proper connections of the wire harness installation to the engine nacelle fire extinguisher, in accordance with Saab Service Bulletin SAAB 340-26-012, Revision 1, dated October 5, 1993, or Saab Service Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995. Prior to further flight, correct any discrepancy found and modify the wiring, in accordance with the service bulletin. After the effective date of this AD, perform this inspection and correct any discrepancy found, in accordance with Saab Service Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995.

(b) Repeat the inspection specified in paragraph (a) of this AD immediately following any maintenance action during which both electric connectors to either of the fire extinguishers in the nacelle electrical bays are disconnected.

(c) Prior to the accumulation of 4,000 hours time-in-service after the effective date of this AD, or at the next scheduled maintenance inspection after the effective date of this AD, whichever occurs earlier:

(1) Conduct an inspection to ensure proper connection of the wire harness installation to the fire extinguisher cartridges in both engine nacelles, in accordance with Saab Service Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995. If any discrepancy is detected, prior to further flight, correct this discrepancy in accordance with the service bulletin.

(2) After the inspection required by paragraph (c)(1) of this AD has been accomplished, measure the total length of the wiring harness from the clamp to connector 9WB- P2/10WB-P2, in accordance with Saab Service Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995. If the wiring harness has been modified with a loop in accordance with the requirements of paragraph (a) of this AD, or in accordance with Saab Service Bulletin SAAB 340- 26-012, Revision 1, dated October 5, 1993, before measuring, remove the loop in the wire harness in accordance with Saab Service Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995.

(i) If the total length is 7 inches (180 mm) or less, no further action is required by this AD.

(ii) If the total length exceeds 7 inches (180 mm), modify this wiring in accordance with Saab Service Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995. Accomplishment of this modification constitutes terminating action for the repetitive inspections required byparagraph (b) of this AD, and no further action is required by this AD.

NOTE 2: Accomplishment of this modification in accordance with Saab Service Bulletin SAAB 340-26-015, dated November 23, 1995, prior to the effective date of this AD, is considered acceptable for compliance with the requirements of paragraph (c)(2)(ii) of this AD.

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

(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.

(f) The actions shall be done in accordance with Saab Service Bulletin SAAB 340-26-012, Revision 1, dated October 5, 1993, and/or Saab Service Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995. The incorporation by reference of Saab Service Bulletin SAAB 340-26-012, Revision 1, dated October 5, 1993, was approved previously by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51, as of February 16, 1994 (59 FR 4575, February 1, 1994). The incorporation by reference of Saab Service Bulletin SAAB 340-26-015, Revision 1, dated December 8, 1995, is 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 SAAB Aircraft AB, SAAB Aircraft Product Support, S-581.88, Linkoping, Sweden. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(g) This amendment becomes effective on September 5, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 94-03-06, amendment 39-8813 (59 FR 4575, February 1, 1994), which is applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes, was published in the Federal Register on April 9, 1997 (62 FR 17127). The action proposed to continue to require repetitive inspections to detect improper connections of the wire harness installation to the cartridges of the fire extinguishers in the engine nacelles, and correction of any discrepancies. The action also proposed to require a revised modification of the wiring to one of the electrical connectors if it exceeds a certain length. Accomplishment of the modification would terminate the repetitive inspections of the wiring currently required by AD 94-03-06.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received.

The commenter supports the proposed 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 as proposed.

Cost Impact
There are approximately 235 Saab Model SAAB SF340A and SAAB 340B series airplanes of U.S. registry that will be affected by this AD.

The actions that are currently required by AD 94-03-06 take approximately 6 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 previously required actions on U.S. operators is estimated to be $77,760, or $360 per airplane. (At the time AD 94-03-06 went into effect, it was estimated that 216 airplanes would be affected.)

The new actions that are required by this new AD will take approximately 6 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will be provided at no cost to operators. Based on these figures, the cost impact of the new requirements of this AD on U.S. operators is estimated to be $84,600, or $360 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 39.13 is amended by removing amendment 39-8813 (59 FR 4575, February 1, 1994), and by adding a new airworthiness directive (AD), amendment 39-10095, to read as follows: