AD 97-03-18

This amendment adopts a new airworthiness directive (AD), applicable to certain Saab Model SAAB SF340A, SAAB 340B, and SAAB 2000 series airplanes, that requires replacement of the hubcap drive coupling of the main wheel with an improved coupling. This amendment is prompted by reports of unexpected decreases in the pressure of the main wheel brake due to incorrect engagement between the main wheel coupling and the wheel speed transducer, which can result in false signals being sent to the anti-skid control box. The actions specified by this AD are intended to prevent loss of brake effectiveness due to a decrease in the pressure of the main wheel brake.

Final rule

97-03-18 SAAB AIRCRAFT AB: Amendment 39-9923. Docket 96-NM-69-AD.
Applicability: Model SAAB SF340A series airplanes having serial numbers 004 through 159 inclusive; Model SAAB 340B series airplanes having serial numbers 160 through 378 inclusive; and Model SAAB 2000 series airplanes having serial numbers 002 through 029 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 (c) 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 loss of brake effectiveness due to a decrease in pressure of the main wheel brake, accomplish the following:

(a) Within 90 days after the effective date of this AD, replace each main wheel hubcap drive coupling having part number (P/N) 40-91115 with a main wheel hubcap drive coupling having P/N 40-91115, Rev. D, in accordance with Saab Service Bulletin SAAB 340-32-107, dated January 18, 1996 (for Model SAAB SF340A and SAAB 340B series airplanes), or Saab Service Bulletin SAAB 2000-32-019, dated January 18, 1996 (for Model SAAB 2000 series airplanes), as applicable.

NOTE 2: The Saab service bulletins reference Crane Hydro-Aire Division Service Bulletins 140-041-32-1 (for wheel hubcaps having part number 140-04120) and 140-159-32-1 (for wheel hubcaps having part number 140-15920), both dated December 21, 1995, as additional sources of service information for replacement of the hubcap drive coupling.

(b) As of the effective date of this AD, no person shall install on any airplane a main wheel hubcap drive coupling having P/N 40-91115 in a wheel hubcap having P/N 140-04120 (for Model SAAB SF340A and SAAB 340B series airplanes), or P/N 140-15920 (for Model SAAB 2000 series airplanes), as applicable.

(c) 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, 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, Los Angeles ACO.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.

(d) 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.

(e) The replacement shall be done in accordance with Saab Service Bulletin SAAB 340-32-107, dated January 18, 1996, or Saab Service Bulletin SAAB 2000-32-019, dated January 18, 1996, as applicable. 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, Linkoping, Sweden. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on March 19, 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 certain Saab Model SAAB SF340A, SAAB 340B, and SAAB 2000 series airplanes was published in the Federal Register on September 4, 1996 (61 FR 46572). That action proposed to require replacement of the hubcap drive coupling of the main wheel with an improved coupling.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public.

Conclusion
The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact
The FAA estimates that 235 Model SAAB SF340A and SAAB 340B series airplanes and 3 Model SAAB 2000 series airplanes of U.S. registry will be affected by this AD.

For Model SAAB SF340A and SAAB340B series airplanes, it will take approximately 2 work hours per airplane to accomplish the required actions, at an average labor rate of $60 per work hour. Required parts will cost approximately $200 per airplane. Based on these figures, the cost impact of the AD on U.S. operators of Model SAAB 340A and SAAB 340B series airplanes is estimated to be $75,200, or $320 per airplane.

For Model SAAB 2000 series airplanes, it will take approximately 2 work hours per airplane to accomplish the required actions, at an average labor rate of $60 per work hour. Required parts will cost approximately $120 per airplane. Based on these figures, the cost impact of the proposed AD on U.S. operators of Model SAAB 2000 series airplanes is estimated to be $720, or $240 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 adding the following new airworthiness directive: