[Federal Register Volume 65, Number 3 (Wednesday, January 5, 2000)]
[Proposed Rules]
[Pages 395-396]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-138]



[[Page 395]]

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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).

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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 9:00 a.m. and 3:00 p.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 filed in 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. 00-138 Filed 1-4-00; 8:45 am]
BILLING CODE 4910-13-U