[Federal Register Volume 64, Number 135 (Thursday, July 15, 1999)]
[Proposed Rules]
[Pages 38150-38152]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18100]


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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: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to certain Saab Model SAAB SF340A and SAAB 
340B series airplanes, that would have required 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. That proposal also would have required 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 
have constituted terminating action for the repetitive inspections 
proposed by that AD. That proposal was prompted by the issuance of 
mandatory continuing airworthiness information by a foreign civil 
airworthiness authority. This new action revises the proposed rule by 
adding repetitive x-ray inspections. The actions specified by this new 
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 August 9, 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 a.m. and 3 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. 98-NM-220-AD, 1601 Lind Avenue, SW, Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Saab Model SAAB SF340A and SAAB 340B series airplanes, was 
published as a notice of proposed rulemaking (NPRM) in the Federal 
Register on February 18, 1999 (64 FR 8029). That NPRM would have 
required 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. That proposal also 
would have required 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 have constituted terminating 
action for the repetitive inspections proposed by that AD. That NPRM 
was prompted by the issuance of mandatory continuing airworthiness 
information by a foreign civil airworthiness authority. Fatigue 
cracking around certain fastener holes of the front spar of the 
horizontal stabilizers, if not detected and corrected, could result in 
failure of the front spar and consequent reduced structural integrity 
of the airplane.

Comments

    Due consideration has been given to the comments received in 
response to the NPRM.

Request To Revise Certain Inspection Requirement of the Proposed 
Rule

    One commenter, the airplane manufacturer, requests that the 
originally proposed rule be revised to clarify certain requirements. 
The commenter notes that the originally proposed rule would require, 
among other things, repetitive eddy current inspections to be 
accomplished in accordance with Saab Service Bulletin 340-55-033, 
Revision 04, dated December 1, 1998. The commenter points out that the 
Saab service bulletin recommends performing both eddy current and x-ray 
inspections. Under the compliance section of the service bulletin, the 
general term ``NDT inspection'' is used. The commenter suggests that 
either ``NDT inspection'' or ``eddy current and x-ray inspection'' be 
specified in the requirements.
    The FAA concurs with this request. The FAA inadvertently omitted 
the reference to repetitive x-ray inspections in paragraphs (a) and (b) 
of the proposed AD, and has revised this supplemental NPRM accordingly. 
Additionally, the reference to x-ray inspections has been added to the 
cost impact section of this supplemental NPRM. The original cost 
estimate in the NPRM included all costs associated with both the eddy 
current and x-ray inspections.

[[Page 38151]]

    Since adding an inspection expands the scope of the originally 
proposed rule, the FAA has determined that it is necessary to reopen 
the comment period to provide additional opportunity for public 
comment.

Clarification of the Inspection Requirements

    Additionally, the FAA has clarified certain wording in the 
supplemental NPRM to more accurately describe the inspection 
requirements. This clarification is in addition to the previously 
discussed omission. Paragraphs (a) and (b) of the proposed rule require 
performing inspections to detect cracking around certain fastener holes 
and adjacent areas of the front spar of the horizontal stabilizer. For 
clarification of the types of inspections required, paragraphs (a) and 
(b) of the supplemental NPRM have been revised to specify that detailed 
visual, eddy current, and x-ray inspections are required in accordance 
with paragraph 2.D. of the Accomplishment Instructions of the service 
bulletin.

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 proposed 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 and x-ray inspections, at an average labor 
rate of $60 per work hour. Based on these figures, the cost impact of 
the inspections 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.


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:

Initial and Repetitive Inspections

    (a) For Model SAAB SF340A series airplanes with manufacturer's 
serial numbers -004 through -159 inclusive: Perform the inspections 
(detailed visual, eddy current, and x-ray) specified in paragraph 
2.D. of the Accomplishment Instructions of Saab Service Bulletin 
340-55-033, Revision 04, dated December 1, 1998, to detect cracking 
around certain fastener holes and adjacent areas of the front spar 
of the horizontal stabilizer, in accordance with the service 
bulletin, at the time specified in paragraph (a)(1), (a)(2), or 
(a)(3) of this AD, as applicable. Thereafter, repeat only the eddy 
current and x-ray inspections 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 and an x-ray 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 and an x-ray 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 and an x-ray inspection within 
1,200 flight cycles after the effective date of this AD.

Initial and Repetitive Inspections

    (b) For Model SAAB 340B series airplanes with manufacturer's 
serial numbers -160 through -439 inclusive: Perform the inspections 
(detailed visual, eddy current, and x-ray) specified in paragraph 
2.D. of the Accomplishment Instructions of Saab Service Bulletin 
340-55-033, Revision 04, dated

[[Page 38152]]

December 1, 1998, to detect cracking around certain fastener holes 
and adjacent areas of the front spar of the horizontal stabilizer, 
in accordance with the service bulletin, at the time specified in 
paragraph (b)(1), (b)(2), or (b)(3) of this AD, as applicable. 
Thereafter, repeat only the eddy current and x-ray inspections 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 and an x-ray 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 and an x-ray 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 and an x-ray inspection within 
1,200 flight cycles after the effective date of this AD.

Corrective Actions

    (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.

Terminating Action

    (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).

Alternative Method of Compliance

    (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.

Special Flight Permits

    (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 July 9, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-18100 Filed 7-14-99; 8:45 am]
BILLING CODE 4910-13-U