[Federal Register Volume 61, Number 79 (Tuesday, April 23, 1996)]
[Rules and Regulations]
[Pages 17825-17826]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-9339]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-121-AD; Amendment 39-9572; AD 96-08-06]


Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Saab Model SAAB SF340A and SAAB 340B series 
airplanes, that requires visual and dye penetrant inspection(s) to 
detect cracks of the nose rib of the rudder, and stop drilling and 
blending of minor cracks. This amendment also requires replacement of 
the nose rib with a new nose rib and reinforcement of the nose rib, if 
extensive cracking is detected or if an operator elects to terminate 
the repetitive inspections. This amendment 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 this 
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: Effective May 23, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 23, 1996.

ADDRESSES: The service information referenced in this AD may be 
obtained from SAAB Aircraft AB, SAAB Aircraft Product Support, S-
581.88, Linkoping, Sweden. This information may be examined at the 
Federal Aviation Administration (FAA), Transport Airplane Directorate, 
Rules Docket, 1601 Lind Avenue SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.

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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Saab Model SAAB SF340A and 
SAAB 340B series airplanes was published in the Federal Register on 
January 9, 1996 (61 FR 640). That action proposed to 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. That action 
also proposed to 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

[[Page 17826]]

operator elects to terminate the repetitive inspections.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the single comment received.
    The commenter supports the proposed rule.
    After careful review of the available data, including the comment 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed.
    The FAA estimates that 221 Saab Model SAAB SF340A and SAAB 340B 
series airplanes of U.S. registry will be affected by this AD, that it 
will take approximately 4 work hours per airplane to accomplish the 
required actions, and that the average labor rate is $60 per work hour. 
Based on these figures, the cost impact of the inspection requirement 
of this AD on U.S. operators is estimated to be $53,040, or $240 per 
airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the requirements of this AD 
action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

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

96-08-06 Saab Aircraft AB: Amendment 39-9572. 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 request approval for an 
alternative method of compliance in accordance with paragraph (b) 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 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 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.
    (d) The actions shall be done in accordance with Saab Service 
Bulletin 340-55-032, dated May 22, 1995. This incorporation by 
reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
obtained from SAAB Aircraft AB, SAAB Aircraft Product Support, S-
581.88, Linkoping, Sweden. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the Office of the Federal Register, 800 North 
Capitol Street NW., suite 700, Washington, DC.
    (e) This amendment becomes effective on May 23, 1996.

    Issued in Renton, Washington, on April 10, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-9339 Filed 4-22-96; 8:45 am]
BILLING CODE 4910-13-U