[Federal Register Volume 65, Number 91 (Wednesday, May 10, 2000)]
[Proposed Rules]
[Pages 30023-30025]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-11723]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-368-AD]
RIN 2120-AA64


Airworthiness Directives; Saab Model SAAB 2000 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 2000 
series airplanes. This proposal would require repetitive detailed 
visual and dye penetrant inspections of the backup struts in the left 
and right nacelles to detect discrepancies; 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 failure of the backup struts in the left and right nacelles due 
to fatigue cracking, which could result in loss of fail-safe redundancy 
in the design of the nacelle in terms of load capability.

DATES: Comments must be received by June 9, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-368-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 99-NM-368-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-368-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Luftfartsverket (LFV), which is the airworthiness authority for 
Sweden, recently notified the FAA that an unsafe condition may exist on 
certain Saab Model SAAB 2000 series airplanes. The LFV advises that 
field experience has revealed fatigue cracking in the internal backup 
struts in the forward part of the nacelle structure. Such cracking was 
found in the area of the welded splices for the upper and lower 
attachment fittings. In the lower end of the attachment fittings, 
cracks were found near the local cut-out in the tube or areas adjacent 
to the welding, and in the upper area in the radius of the attachment 
fittings. On one occasion, fatigue cracks resulted in complete failure 
of the backup strut. Such fatigue cracking, if not corrected, could 
result in failure of the backup struts in the left and right nacelles, 
which could result in loss of fail-safe redundancy in the design of the 
nacelle in terms of load capability.

Explanation of Relevant Service Information

    The manufacturer has issued Saab Service Bulletin 2000-54-023, 
Revision 01, dated January 28, 2000, which describes procedures for 
repetitive detailed visual and dye penetrant inspections of the backup 
struts in the left and right nacelles to detect discrepancies; and 
corrective actions, if necessary. Descriptions of the two types of 
inspections are as follows:
     The initial detailed visual inspection includes the upper 
areas of the backup strut around the welding in the pipe and in the 
attachment fittings.
     The initial dye penetrant inspection, using a Penetrant 
Type 1 (fluorescent dye) sensitivity level 2, includes the lower areas 
of the backup strut around the welding in the pipe and in the 
attachment fittings, and specifies taking special care to check the 
inside edge of the cutouts.
    If any inspection reveals a failed backup strut, procedures include 
the following additional inspections of the engine mount surrounding 
structure:
     Detailed visual inspections of each engine mount strut and 
mounting

[[Page 30024]]

fittings, forward semi-circular collar/frame and aft beam, nacelle 
backup strut opposite side to the failed backup strut and attachment 
fittings at station 176/199, inboard and outboard upper and lower 
longerons of the nacelle, and upper and lower longerons at the 
attachment to the inboard and outboard upper and lower fittings of the 
nacelle.
     General visual inspections of the inner and outer side 
walls and side of the skin panels.
    Discrepancies include fatigue cracking, a failed backup strut, and 
damage to the surrounding structure of the engine mount. Corrective 
actions include replacing any failed backup strut located in the 
hydraulic bay or electrical bay areas with a new backup strut, and 
performing additional inspections of the surrounding structure of the 
engine mount.
    The LFV classified this service bulletin as mandatory and issued 
Swedish airworthiness directive No. 1-150R1, dated January 31, 2000, in 
order to assure the continued airworthiness of these airplanes in 
Sweden.

FAA's Conclusions

    This airplane model is manufactured in Sweden and is 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 repair instructions for 
certain damage conditions, this proposed AD would require the repair of 
those conditions 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 a repair approved 
by either the FAA or the LFV would be acceptable for compliance with 
this proposed AD.

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Cost Impact

    The FAA estimates that 3 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 8 work 
hours per airplane to accomplish the proposed inspections, 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 
$1,440, or $480 per airplane, per inspection cycle.
    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 a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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-368-AD.
    Applicability: Model SAAB 2000 series airplanes, serial numbers 
-004 through -063 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 failure of the backup struts in the left and right 
nacelles due to fatigue cracking, which could result in loss of 
fail-safe redundancy in the design of the nacelle in terms of load 
capability, accomplish the following:
    Repetitive Inspections
    (a) For airplanes on which the dye penetrant inspection of the 
backup struts in the left and right nacelles specified in Saab Alert 
Service Bulletin 2000-A54-022, dated
    October 27, 1999, has not been accomplished prior to the 
effective date of this AD:
    Within 200 flight hours after the effective date of this AD, 
accomplish paragraphs (b)(1) and (b)(2) of this AD in accordance 
with the Accomplishment Instructions of Saab Service Bulletin 2000-
54-023, Revision 01, dated January 28, 2000.
    (b) For airplanes on which the dye penetrant inspection of the 
backup struts in the left and right nacelle specified in Saab Alert 
Service Bulletin 2000-A54-022, dated October 27, 1999, has been 
accomplished prior to the effective date of this AD: Within 450 
flight hours after the effective date of this AD, accomplish 
paragraphs (b)(1) and (b)(2) of this AD in accordance with the 
Accomplishment Instructions of Saab Service Bulletin 2000-54-023, 
Revision 01, dated January 28, 2000.

[[Page 30025]]

    (1) Perform a detailed visual inspection of the upper areas of 
the backup strut around the welding in the pipe and in the 
attachment fittings to detect any discrepancy (including fatigue 
cracking or a failed backup strut) by accomplishing all actions 
specified in paragraph B.(1) of the Accomplishment Instructions of 
the service bulletin, in accordance with that service bulletin. 
Repeat the detailed visual inspection thereafter at intervals not to 
exceed 450 flight hours.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids 
(e.g., mirror, magnifying lenses) may be used. Surface cleaning and 
elaborate access procedures may be required.''

    (2) Perform a dye penetrant inspection, using Penetrant Type 1 
(fluorescent dye) sensitivity level 2, of the lower areas of the 
backup strut around the welding in the pipe and in the attachment 
fittings to detect any discrepancy (including fatigue cracking or a 
failed backup strut) by accomplishing all actions specified in 
paragraphs B.(2) and B.(3) of the service bulletin, as applicable, 
in accordance with that service bulletin.
    (i) For airplanes on which all backup struts have accumulated 
less than 4,500 total flight hours as of the effective date of this 
AD, repeat the dye penetrant inspection thereafter at intervals not 
to exceed 1,650 flight hours, until any backup strut on the airplane 
has accumulated 4,500 total flight hours; then perform the 
repetitive inspection thereafter at the interval specified by 
paragraph (b)(2)(ii) of this AD.
    (ii) For airplanes on which any backup strut has accumulated 
4,500 or more total flight hours as of the effective date of this 
AD, repeat the dye penetrant inspection thereafter at intervals not 
to exceed 900 flight hours.

Corrective Actions

    (c) If any discrepancy (including fatigue cracking, a failed 
backup strut, or damage to the surrounding structure of the engine 
mount) is detected during any inspection required by this AD: Prior 
to further flight, accomplish the applicable corrective actions 
(including performing additional inspections of the engine mount 
surrounding structure, and replacing any discrepant backup strut in 
the hydraulic or electrical bay areas with a new backup strut) 
specified by paragraph C. of the Accomplishment Instructions of Saab 
Service Bulletin 2000-54-023, Revision 01, dated January 28, 2000, 
in accordance with that service bulletin. For any repair condition 
for which the service bulletin specifies to contact the manufacturer 
for appropriate
ACTION: Prior to further flight, repair in accordance with a method 
approved by either the Manager, International Branch, ANM-116, FAA, 
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. 
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. 1-150R1, dated January 31, 2000.


    Issued in Renton, Washington, on May 4, 2000.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-11723 Filed 5-9-00; 8:45 am]
BILLING CODE 4910-13-U