Airworthiness directives: Saab,

[Federal Register: January 5, 2000 (Volume 65, Number 3)]

[Proposed Rules]

[Page 395-396]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr05ja00-16]

[[Page 395]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-51-AD]

RIN 2120-AA64

Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes. This proposal would require a one-time inspection to detect corrosion and scratches on the bearing housing surfaces of the support assembly on the main landing gear (MLG), and corrective actions, if necessary. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent corrosion in the inboard and outboard bearing housings of the MLG support assembly, which could result in fatigue cracks in the support assembly and lead to failure of the MLG.

DATES: Comments must be received by February 4, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-51-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00a.m. and 3:00p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained from Saab Aircraft AB, SAAB Aircraft Product Support, S- 581.88, Linkoping, Sweden. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

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.

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.

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 filedin the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 99-NM-51-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-51-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The Luftfartsverket (LFV), which is the airworthiness authority for Sweden, notified the FAA that an unsafe condition may exist on certain Saab Model SAAB SF340A and SAAB 340B series airplanes. The LFV advises that, during replacement of landing gear support assembly bearings, pitting corrosion has been found in the outboard and inboard bearing housings. The corrosion is believed to be caused by intrusion of moisture between the bearing and its housing surface. Such corrosion, if not corrected, could result in fatigue cracks in the support assembly and lead to failure of the main landing gear (MLG).

Explanation of Relevant Service Information

Saab has issued Service Bulletin 340-57-036, dated October 20, 1999, which describes a one-time visual inspection to detect corrosion and scratches on the bearing housing surfaces of the support assembly on the MLG. The service bulletin also describes procedures for corrosion removal, an eddy current inspection, and repair if corrosion or scratches are found. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition. The LFV classified this service bulletin as mandatory and issued Swedish airworthiness directive No. 1-146, dated October 20, 1999, in order to ensure the continued airworthiness of these airplanes in Sweden.

FAA's Conclusions

These airplane models are manufactured in Sweden and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the LFV has kept the FAA informed of the situation described above. The FAA has examined the findings of the LFV, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, the proposed AD would require accomplishment of the actions specified in the service bulletin described previously, except as described below.

Differences Between Proposed AD and Service Bulletin

Operators should note that, although the service bulletin specifies that the manufacturer may be contacted for disposition of certain conditions, this proposal would require the repair of those conditions to be accomplished in accordance with a method approved by the FAA or the LFV.

[[Page 396]]

Cost Impact

The FAA estimates that 291 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 2 work hours per airplane to accomplish the proposed inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $34,920, or $120 per airplane.

The cost impact figure discussed above is 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.

Regulatory Impact

The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

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.

   Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

   SAAB Aircraft AB: Docket 99-NM-51-AD.

   Applicability: Model SAAB SF340A, serial numbers 004 through 159 inclusive; and SAAB 340B series airplanes, serial numbers 160 through 444 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 (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 not been eliminated, the request should include specific proposed actions to address it.

   Compliance: Required as indicated, unless accomplished previously.

   To prevent corrosion in the inboard and outboard bearing housings of the support assembly of the main landing gear (MLG), which could result in fatigue cracks in the support assembly and lead to failure of the MLG, accomplish the following:

   (a) At the applicable time specified in paragraph (a)(1), (a)(2), (a)(3), or (a)(4) of this AD: Perform a one-time general visual inspection of the eight bearing housing surfaces of the MLG to detect corrosion or scratches, in accordance with Saab Service Bulletin 340-57-036, dated October 20, 1999.

   (1) For airplanes with 32,000 or more total flight cycles as of the effective date of this AD, the inspection is to be performed within 4,000 flight cycles after the effective date of this AD.

   (2) For airplanes with 24,000 or more and fewer than 32,000 total flight cycles as of the effective date of this AD, the inspection is to be performed within 6,000 flight cycles after the effective date of this AD.

   (3) For airplanes with 12,000 or more and fewer than 24,000 total flight cycles as of the effective date of this AD, the inspection is to be performed prior to the accumulation of 24,000 total flight cycles, or within 6,000 flight cycles after the effective date of this AD, whichever occurs later.

   (4) For airplanes with fewer than 12,000 total flight cycles as of the effective date of this AD, the inspection is to be performed prior to the accumulation of 12,000 total flight cycles, or within 6,000 flight cycles after the effective date of this AD, whichever occurs later.

   Note 2: For the purposes of this AD, a general visual inspection is defined as: ``A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.''

   (b) Except as provided by paragraph (c) of this AD: If, during the inspection required by paragraph (a) of this AD, any corrosion or scratch is detected that is within the limits specified in Saab Service Bulletin 340-57-036, dated October 20, 1999, prior to further flight, perform corrective actions (including rework, an eddy current inspection, and repair) in accordance with steps 2.B. and 2.C. of the Accomplishment Instructions of the service bulletin.

   (c) If, during any inspection required by this AD, a discrepancy is detected for which the service bulletin specifies to contact Saab for appropriate action [including any crack or any corrosion or scratch that exceeds 1.1 mm (0.043 in) after applicable rework has been performed as required by paragraph (b) of this AD]: Prior to further flight, repair in accordance with a method approved by the Manager, International Branch, ANM-116, Transport Airplane Directorate; or the Luftfartsverket (LFV) (or its delegated agent). For a repair method to be approved by the Manager, International Branch, ANM-116, as required by this paragraph, the Manager's approval letter must specifically reference this AD.

   Alternative Methods of Compliance

   (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, International Branch, ANM-116, 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, International Branch, ANM-116.

   Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

   Special Flight Permits

   (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.

   Note 4: The subject of this AD is addressed in Swedish airworthiness directive No. 1-146, dated October 20, 1999.

   Issued in Renton, Washington, on December 29, 1999. D. L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

   [FR Doc. 00-138Filed1-4-00; 8:45 am]

   BILLING CODE 4910-13-U