[Federal Register Volume 61, Number 6 (Tuesday, January 9, 1996)]
[Proposed Rules]
[Pages 640-642]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-263]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-121-AD]


Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B

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 visual and dye 
penetrant inspection(s) to detect cracks of the nose rib of the rudder, 
and stop drilling and blending of minor cracks. The proposal would also 
require replacement of the nose rib with a new nose rib and 
reinforcement of the nose rib, if estensive cracking is detected or if 
an operator elects to terminate the repetitive inspections. This 
proposal is prompted by the result of an inspection that revealed a 
cracked nose rib on the front spar of the rudder due to vibration-
related stress. The actions specified by the proposed AD are intended 
to prevent such stress and cracking, which could result in the 
deformation of the nose rib; this condition may lead to friction and 
jamming between the fin and the rudder and subsequent reduced 
controllability of the airplane.

DATES: Comments must be received by February 20, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-121-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: Ruth Harder, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-1721; fax (206) 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 95-NM-121-AD.'' The 

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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-103, Attention: Rules 
Docket No. 95-NM-121-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 SF340A and SAAB 340B series airplanes. The LFV 
advises that, during a normal zonal inspection of one of these 
airplanes, a cracked nose rib was found on the front spar of the 
rudder. The cause of such cracking has been attributed to vibration-
related stress to the nose rib. This condition, if not corrected, could 
result in cracking and subsequent deformation of the nose rib; this 
condition consequently may lead to friction and jamming between the fin 
and the rudder, and subsequent reduced controllability of the airplane.
    Saab has issued Service Bulletin 340-55-032, dated May 22, 1995, 
which describes procedures for visual and dye penetrant inspection(s) 
to detect cracks of the nose rib of the rudder, and stop drilling and 
blending of minor cracks. The service bulletin also describes 
procedures for replacement of the nose rib with a new nose rib and 
reinforcement of the nose rib, if any extensive crack is detected or if 
an operator elects to terminate the repetitive inspections. The 
reinforcement will thicken the nose rib, and, thus, dampen the 
vibration. The LFV classified this service bulletin as mandatory and 
issued Swedish airworthiness directive (SAD) 1-074, effective date May 
22, 1995, in order to assure the continued airworthiness of these 
airplanes in Sweden.
    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.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, the 
proposed AD would require visual and dye penetrant inspection(s) to 
detect cracks of the nose rib of the rudder, and stop drilling and 
blending of minor cracks. The proposed AD would also require 
replacement of the nose rib with a new nose rib and reinforcement of 
the nose rib, if any extensive crack is detected or if an operator 
elects to terminate the repetitive inspections. The actions would be 
required to be accomplished in accordance with the service bulletin 
described previously.
    The FAA estimates that 221 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 4 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 inspection proposed AD on U.S. operators is 
estimated to be $53,040, or $240 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.
    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), 40101, 40113, 44701.


Sec. 39.13  [Amended]

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

Saab Aircraft AB: Docket 95-NM-121-AD.

    Applicability: Model SAAB SF340A series airplanes having serial 
numbers (S/N) 004 through 159 inclusive, and Model SAAB 340B having 
S/N's 160 through 369 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 use the authority 
provided in paragraph (b) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent vibration-related stress and cracking and consequent 
deformation of the nose rib, which could result in friction and 
jamming between the fin and the rudder and subsequent reduced 
controllability of the airplane, accomplish the following:
    (a) Prior to the accumulation of 2,400 total flight hours, or 
within 800 flight hours after the effective date of this AD, 
whichever occurs later, perform a visual and dye penetrant 
inspection to detect cracks of the nose rib of the rudder, in 
accordance with Saab Service Bulletin 340-55-032, dated May 22, 
1995.
    (1) If no cracks are detected, repeat the inspection thereafter 
at intervals not to exceed 800 flight hours, or replace the nose rib 
with a new nose rib and reinforce it, in accordance with the service 
bulletin. Accomplishment of the replacement and reinforcement 
constitutes terminating action for this AD.
    (2) If any minor crack [less than 25.4 mm (1.0 inch) long] is 
detected, prior to further 

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flight, stop drill and blend the crack in accordance with the service 
bulletin. Repeat the inspection thereafter at intervals not to 
exceed 800 flight hours, or replace the nose rib with a new nose rib 
and reinforce it, in accordance with the service bulletin. 
Accomplishment of the replacement and reinforcement constitutes 
terminating action for this AD.
    (3) If any extensive crack [greater than or equal to 25.4 mm 
(1.0 inch) long] is detected, prior to further flight, replace the 
nose rib with a new nose rib and reinforce it, in accordance with 
the service bulletin. Accomplishment of this replacement and 
reinforcement constitutes terminating action for this AD.
    (b) 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, Standardization Branch, ANM-113, 
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, 
Standardization Branch, ANM-113.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    (c) 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.

    Issued in Renton, Washington, on January 3, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-263 Filed 1-8-96; 8:45 am]
BILLING CODE 4910-13-U