AD 98-20-11

This amendment adopts a new airworthiness directive (AD), applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes, that requires repetitive detailed visual inspections of the windshield wiper assembly for discrepant conditions, and corrective actions, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent failure of the windshield wiper assembly, which could result in loss of visibility; or damage to the propeller(s), possible penetration of the fuselage skin, and consequent depressurization of the airplane.

Final rule

98-20-11 SAAB AIRCRAFT AB (Formerly SAAB Fairchild): Amendment 39-10778. Docket 98-NM-100-AD.
Applicability: Model SAAB SF340A series airplanes, manufacturer's serial numbers 004 through 159 inclusive; and SAAB 340B series airplanes, manufacturer's serial numbers 160 through 399 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 (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 condition has not been eliminated,the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the windshield wiper assembly, which could result in loss of visibility; or damage to the propeller(s), possible penetration of the fuselage skin, and consequent depressurization of the airplane, accomplish the following:

(a) Prior to the accumulation of 4,000 total flight hours, or within 3 months after the effective date of this AD, whichever occurs later, perform a detailed visual inspection of the windshield wiper assembly for discrepancies (corrosion; excessive wear; missing, loose, or broken parts; improper alignment; and insecure attachment), in accordance with Saab Service Bulletin 340- 30-081, dated November 14, 1997, including Attachment 1, Revision 1, dated September 14, 1997.

(1) If no discrepancy is detected during the inspection, repeat the inspection thereafter at intervals not to exceed 4,000 flight hours.

(2) If any discrepancy is detected during any inspection, prior to further flight, replace the windshield wiper assembly with a new or serviceable windshield wiper assembly, or repair in accordance with Saab Service Bulletin 340-30-081, dated November 14, 1997, including Attachment 1, Revision 1, dated September 14, 1997. Repeat the detailed visual inspection thereafter at intervals not to exceed 4,000 flight hours.

(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, International Branch, ANM-116, FAA Transport Airplane Directorate. Operators shall submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from theInternational Branch, ANM-116.

(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 actions shall be done in accordance with Saab Service Bulletin 340-30-081, dated November 14, 1997, including Attachment 1, Revision 1, dated September 14, 1997. The service bulletin contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date
Shown on Page
1-4
Original
November 14, 1997

ATTACHMENT 1

1-4
1
September 14, 1997

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 Saab Aircraft AB, SAAB Aircraft Product Support, S-581.88, Link ping, Sweden. 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 Swedish airworthiness directive 1-115R1, dated November 17, 1997.

(e) This amendment becomes effective on October 28, 1998.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.

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 certain Saab Model SAAB SF340A and SAAB 340B series airplanes was published in the Federal Register on April 21, 1998 (63 FR 19686). That action proposed to require repetitive, detailed visual inspections of the windshield wiper assembly for discrepant conditions, and corrective actions, if necessary.

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

One commenter opposes the proposed rule. The commenter states that the Saab Maintenance Review Board (MRB) report covers the items addressed by the proposal during routine line checks. The commenter believes such compliance is more than sufficient to address the unsafe condition.

The FAA does not agree with the remarks of this commenter. The FAA finds that actions performed during routine line checks are not detailed enough to detect the type of defects (i.e., corrosion; excessive wear; missing, loose, or broken parts; improper alignment; and insecure attachment of the windshield wiper assembly) addressed in this AD. This is further evidenced by the fact that failures have occurred in service even though the routine line checks referenced by the commenter were included in the current MRB report. The FAA finds that no change to the final rule is necessary in this regard.

The manufacturer requests that the repetitive inspection interval be increased from 1,000 to 4,000 flight hours. The commenter states that the proposed interval is too conservative, even though the time necessary to perform the inspection is less than one work hour. The commenter bases its remarks on the fact that the SAAB 340 fleet has accumulated 6,110,000 flight hours as of the end of December 1997 with two known incidents. The commenter submits data that use vendor figures regarding proven capability of the wiper system, and estimated hours of usage of the wiper system. Based on that data, the commenter concludes that the interval recommended for the general visual inspection in the existing MRB task is a safe interval.

The FAA concurs. The FAA finds that the data submitted by the commenter demonstrate that a repetitive inspection interval of 4,000 flight hours is sufficient to address the unsafe condition addressed by this AD. The final rule has been revised accordingly.

The manufacturer also requests that the proposed rule be revised to specify that repairs should be accomplished in accordance with Saab Service Bulletin 340-30-081 (which is referenced in the proposal as the appropriate source of service information for accomplishment of the inspections) and with reference to the Component Maintenance Manual.

The FAA concurs with the commenter's request. The Saab service bulletin includes an attachment(Rosemount Aerospace, Inc., Service Bulletin 2314M-30-17, Revision 1, dated September 14, 1997); paragraph II.B. of this attachment describes procedures for repair or replacement of the windshield wiper arm assembly. The attachment also specifies certain sections of the Component Maintenance Manual as a source of additional service information. The FAA has determined that the procedures specified in the attachment should be referenced in this final rule for accomplishment of the repair, and has revised the AD accordingly.

Conclusion
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. 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 254 Saab Model SAAB SF340A and SAAB 340B series airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $15,240, or $60 per airplane, per inspection cycle.

The cost impact figure discussed above is 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 thepreparation 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 adding the following new airworthiness directive:
requirements of the Airworthiness Directive (reference FAR Subpart 39.3).