[Federal Register Volume 64, Number 32 (Thursday, February 18, 1999)]
[Proposed Rules]
[Pages 8029-8031]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-4013]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-220-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 repetitive 
inspections to detect cracking around certain fastener holes and 
adjacent areas of the front spar of the horizontal stabilizers; and 
corrective actions, if necessary. This proposal also would require cold 
working of certain fastener holes of the front spar of the horizontal 
stabilizers, and follow-on actions; and installation of new fasteners, 
which would constitute terminating action for the repetitive 
inspections proposed by this AD. 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 failure of the front spar due to fatigue cracking 
around certain fastener holes of the front spar of the horizontal 
stabilizers, which could result in reduced structural integrity of the 
airplane.

DATES: Comments must be received by March 22, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-220-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 98-NM-220-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.

[[Page 8030]]

98-NM-220-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 full-scale fatigue testing on a test article, cracking was 
found in the front spar of the horizontal stabilizer at the 
intersection between the rear fuselage and the front upper spar cap. 
Further investigation revealed that the fatigue cracking may have 
originated at one of the fastener holes in the upper part of the web of 
the front spar. Such fatigue cracking, if not detected and corrected, 
could result in reduced structural integrity of the airplane.

Explanation of Relevant Service Information

    The manufacturer has issued SAAB Service Bulletin 340-55-033, 
Revision 04, dated December 1, 1998, which describes procedures for 
repetitive detailed visual and eddy current inspections to detect 
cracking around certain fastener holes and adjacent areas of the front 
spar of the horizontal stabilizers.
    The manufacturer also has issued SAAB Service Bulletin 340-55-034, 
dated October 16, 1998, which describes procedures for cold working of 
certain fastener holes of the front spar of the horizontal stabilizers, 
and follow-on actions. The follow-on actions involve performing eddy 
current inspections of specified areas to detect cracking of certain 
fastener holes before and after cold working and after oversizing any 
hole. The service bulletin also describes procedures for installation 
of new fasteners into certain holes of the front spar of the horizontal 
stabilizers. Accomplishment of these actions would eliminate the need 
for the repetitive inspections described in Saab Service Bulletin 340-
55-033.
    Accomplishment of the actions specified in the Saab service 
bulletins is intended to adequately address the identified unsafe 
condition. The LFV classified these service bulletins as mandatory and 
issued Swedish airworthiness directives 1-110R2, dated December 7, 
1998, and 1-133, dated October 20, 1998, in order to assure 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 bulletins described previously, 
except as discussed below.

Differences Between Proposed Rule and Service Information

    Operators should note that, although the service bulletins specify 
that the manufacturer may be contacted for the disposition of certain 
cracking conditions around certain fastener holes of the front spar of 
the horizontal stabilizers, this AD would require repair of any fatigue 
cracking to be accomplished in accordance with a method approved by 
either the FAA, or the LFV (or its delegated agent). In light of the 
type of repair that would be required to address the identified unsafe 
condition, and in consonance with existing bilateral airworthiness 
agreements, the FAA has determined that, for this AD, a repair approved 
by either the FAA or the LFV is acceptable for compliance with this AD.

Cost Impact

    The FAA estimates that 279 airplanes of U.S. registry would be 
affected by this proposed AD.
    It would take approximately 4 work hours per airplane to perform 
the detailed visual inspection, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the inspection 
proposed by this AD on U.S. operators is estimated to be $66,960, or 
$240 per airplane, per inspection cycle.
    It would take approximately 6 work hours per airplane to accomplish 
the proposed eddy current inspection, at an average labor rate of $60 
per work hour. Based on these figures, the cost impact of the 
inspection proposed by this AD on U.S. operators is estimated to be 
$100,440, or $360 per airplane, per inspection cycle.
    It would take approximately 42 work hours to accomplish the cold 
working of the fastener holes, at an average labor rate of $60 per work 
hour. Required parts would cost approximately $400 per airplane. Based 
on these figures, the cost impact of the cold work proposed by this AD 
on U.S. operators is estimated to be $814,680, or $2,920 per airplane.
    The cost impact figures discussed above are 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.

[[Page 8031]]

Sec. 39.13  [Amended]

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

Saab Aircraft AB: Docket 98-NM-220-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 -
439 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 (f) 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 front spar due to fatigue cracking 
around certain fastener holes of the front spar of the horizontal 
stabilizers, which could result in reduced structural integrity of 
the airplane, accomplish the following:
    (a) For SAAB SF340A series airplanes with manufacturer's serial 
numbers -004 through -159 inclusive: Perform inspections to detect 
cracking around certain fastener holes and adjacent areas of the 
front spar of the horizontal stabilizer, in accordance with Saab 
Service Bulletin 340-55-033, Revision 04, dated December 1, 1998, at 
the time specified in paragraph (a)(1), (a)(2), or (a)(3) of this 
AD, as applicable. Thereafter, repeat the eddy current inspection at 
intervals not to exceed 12,000 flight cycles until the requirements 
of paragraph (d) of this AD are accomplished.
    (1) For airplanes that have accumulated less than 22,000 total 
flight cycles as of the effective date of this AD: Perform an eddy 
current inspection prior to the accumulation of 22,000 total flight 
cycles, or within 2,000 flight cycles after the effective date of 
this AD, whichever occurs later.
    (2) For airplanes that have accumulated 22,000 or more total 
flight cycles and less than 30,000 total flight cycles as of the 
effective date of this AD: Accomplish the requirements of paragraphs 
(a)(2)(i) and (a)(2)(ii) of this AD.
    (i) Perform a detailed visual inspection within 800 flight 
cycles after the effective date of this AD; and
    (ii) Perform an eddy current inspection within 2,000 flight 
cycles after the effective date of this AD.
    (3) For airplanes that have accumulated 30,000 or more total 
flight cycles as of the effective date of this AD: Accomplish the 
requirements of paragraphs (a)(3)(i) and (a)(3)(ii) of this AD.
    (i) Perform a detailed visual inspection within 400 flight 
cycles after the effective date of this AD; and
    (ii) Perform an eddy current inspection within 1,200 flight 
cycles after the effective date of this AD.
    (b) For SAAB 340B series airplanes with manufacturer's serial 
numbers -160 through -439 inclusive: Perform inspections to detect 
cracking around certain fastener holes and adjacent areas of the 
front spar of the horizontal stabilizer, in accordance with Saab 
Service Bulletin 340-55-033, Revision 04, dated December 1, 1998, at 
the time specified in paragraph (b)(1), (b)(2), or (b)(3) of this 
AD, as applicable. Thereafter, repeat the eddy current inspection at 
intervals not to exceed 6,000 flight cycles until the requirements 
of paragraph (d) of this AD are accomplished.
    (1) For airplanes that have accumulated less than 12,000 total 
flight cycles as of the effective date of this AD: Perform an eddy 
current inspection prior to the accumulation of 12,000 total flight 
cycles, or within 2,000 flight cycles after the effective date of 
this AD, whichever occurs later.
    (2) For airplanes that have accumulated 12,000 or more total 
flight cycles and less than 16,000 total flight cycles as of the 
effective date of this AD: Accomplish the requirements of paragraphs 
(b)(2)(i) and (b)(2)(ii) of this AD.
    (i) Perform a detailed visual inspection within 800 flight 
cycles after the effective date of this AD; and
    (ii) Perform an eddy current inspection within 2,000 flight 
cycles after the effective date of this AD.
    (3) For airplanes that have accumulated 16,000 or more total 
flight cycles as of the effective date of this AD: Accomplish the 
requirements of paragraphs (b)(3)(i) and (b)(3)(ii) of this AD.
    (i) Perform a detailed visual inspection within 400 flight 
cycles after the effective date of this AD; and
    (ii) Perform an eddy current inspection within 1,200 flight 
cycles after the effective date of this AD.
    (c) If any cracking is detected during any inspection required 
by paragraph (a) or (b) of this AD, prior to further flight, either 
repair in accordance with a method approved by the Manager, 
International Branch, ANM-116, FAA, Transport Airplane Directorate, 
or the Luftfartsverket (LFV) (or its delegated agent); or accomplish 
the requirements of paragraph (d) of this AD.

    Note 2: Inspections to detect cracking around certain fastener 
holes and adjacent areas of the front spar of the horizontal 
stabilizers that have been accomplished prior to the effective date 
of this AD in accordance with Saab Service Bulletin 340-55-033, 
Revision 03, dated January 22, 1998, are considered acceptable for 
compliance with the applicable action specified by this AD.

    (d) For all airplanes: Except as provided by paragraph (e) of 
this AD, accomplish cold working of certain fastener holes of the 
front spar of the horizontal stabilizers, and follow-on actions; and 
install new fasteners; in accordance with Saab Service Bulletin 340-
55-034, dated October 16, 1998; at the time specified in paragraph 
(d)(1), (d)(2), or (d)(3) of this AD, as applicable. Accomplishment 
of this action constitutes terminating action for this AD.
    (1) For all airplanes that have accumulated less than 26,000 
total flight cycles as of the effective date of this AD: Within 
10,000 flight cycles after the effective date of this AD.
    (2) For all airplanes that have accumulated 26,000 or more total 
flight cycles and less than 30,000 total flight cycles as of the 
effective date of this AD: Within 6,000 flight cycles after the 
effective date of this AD.
    (3) For all airplanes that have accumulated 30,000 or more total 
flight cycles as of the effective date of this AD: Within 3,000 
flight cycles after the effective date of this AD.
    (e) If any crack is detected during the accomplishment of 
paragraph (d) of this AD, and if the service bulletin listed in 
paragraph (d) of this AD specifies to contact the manufacturer for 
an appropriate corrective action: Prior to further flight, repair in 
accordance with a method approved by the Manager, International 
Branch, ANM-116, or the LFV (or its delegated agent).
    (f) 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. 
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.
    (g) 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 directives 1-110R2, dated December 7, 1998, and 1-133, 
dated October 20, 1998.

    Issued in Renton, Washington, on February 11, 1999.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-4013 Filed 2-17-99; 8:45 am]
BILLING CODE 4910-13-U