[Federal Register Volume 59, Number 174 (Friday, September 9, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-21361]


[[Page Unknown]]

[Federal Register: September 9, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-234-AD; Amendment 39-9018; AD 94-18-05]

 

Airworthiness Directives; Saab Model 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 SF340A and SAAB 340B series airplanes. 
This amendment requires inspections to detect discrepancies of certain 
main landing gear (MLG) retract actuator bracket retaining bolts; 
replacement of discrepant parts; installation of washers, if necessary; 
and eventual replacement of certain MLG retract actuator bracket 
retaining bolts and certain nose landing gear (NLG) trunnion pin cross 
bolts. This amendment is prompted by reports of extension and 
retraction problems on the MLG, due to loose retract actuator brackets 
on the MLG shock struts. The actions specified by this AD are intended 
to prevent a loose retract actuator bracket from interfering with the 
MLG shock strut trunnion support, which could result in the inability 
of the MLG to extend or retract.

DATES: Effective October 11, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 11, 1994.

ADDRESSES: The service information referenced in this AD may be 
obtained from Saab Aircraft AB, Product Support, S581.88, 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: Mark Quam, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2145; fax (206) 227-1320.

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 SF340A and SAAB 
340B series airplanes was published in the Federal Register on March 
24, 1994 (59 FR 13898). That action proposed to require a one-time 
visual inspection to detect corrosion, cracking, or damage of certain 
MLG retract actuator bracket retaining bolts and to determine if the 
nut is bottoming the threads of certain other bolts; replacement of any 
discrepant bolt; and the installation of washers, if any nut is found 
bottoming the threads. It also proposed to require a one-time visual 
and magnaflux inspection during MLG overhaul to detect any scored, 
cracked, or out-of-tolerance condition of certain MLG retract actuator 
bracket retainer bolts; replacement of any discrepant bolt; and 
eventual replacement of certain MLG retract actuator bracket retaining 
bolts and certain NLG trunnion pin cross bolts.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter supports the proposal.
    Another commenter requests that the proposed rule be revised to 
include reference to Revision 1 of the specified Saab service bulletin. 
The FAA concurs. Since issuance of the notice, Saab has issued Revision 
1 of Service Bulletin 340-32-094, dated March 4, 1994. This revised 
service bulletin is essentially identical to the originally released 
version, which was referenced in the notice, but contains certain 
clarifications, revised illustrations, and provisions for use of an 
alternative washer. The Luftfartsverket, which is the airworthiness 
authority for Sweden, has approved the technical content of this 
revised service bulletin. The FAA has revised the final rule to include 
reference to the revised service bulletin as an additional source of 
appropriate service information.
    This same commenter requests clarification as to whether or not the 
proposed rule would require replacement of corroded bolts if any were 
found during the magnaflux inspection that would be required by 
paragraph (b)(1) of the proposal. The FAA notes that the Saab Service 
Bulletin 340-32-094, which is referenced in the notice, mentions 
hydrogen embrittlement (corrosion) as one of the reasons for fractures 
of the subject retaining bolts; however, that service bulletin does not 
directly address corrosion in its instructions for inspection. That 
service bulletin does contain attachments comprised of several AP 
Precision Hydraulic, Ltd., service bulletins, however, and several of 
those service bulletins do contain instructions for visually inspecting 
the retainer bolts for corrosion, cracking, or damage, and removing any 
bolt that exhibits such discrepancies. Further, the FAA points out 
that, under normal maintenance practices, these bolts are inspected 
visually to detect cracks, corrosion, or other damage whenever they are 
removed, and are replaced if discrepancies exist. Since the bolts must 
be removed for the visual and magnaflux inspections required by 
paragraph (b)(1) of the rule, they would necessarily be inspected for 
corrosion at that time if normal maintenance practices are followed. 
The FAA has added ``Note 1'' to paragraph (b)(1) of the final rule to 
remind operators of the need to visually inspect the bolts for 
corrosion and to replace any corroded bolts.
    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 with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    The FAA estimates that 217 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 $55 per work hour. Required parts will be provided at no cost 
to operators. Based on these figures, the total cost impact of the AD 
on U.S. operators is estimated to be $47,740, or $220 per airplane.
    The total 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 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


39.13  [Amended]

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

94-18-05  Saab Aircraft AB: Amendment 39-9018. Docket 93-NM-234-AD.

    Applicability: Saab Model SF340A series airplanes, serial 
numbers 004 through 159, inclusive; and SAAB 340B series airplanes, 
serial numbers 160 through 346, inclusive; certificated in any 
category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent the inability of the main landing gear (MLG) to 
extend or retract, accomplish the following:
    (a) Within 600 landings after the effective date of this AD, or 
within 120 days after the effective date of this AD, whichever 
occurs earlier, accomplish the requirements of paragraphs (a)(1) and 
(a)(2) in accordance with Paragraphs 2.A. and 2.B. of the 
Accomplishment Instructions of Saab Service Bulletin 340-32-094, 
dated October 29, 1993, or Revision 1, dated March 4, 1994.
    (1) Perform a visual inspection of each MLG retract actuator 
bracket retaining bolt, Item 792A or 792 [part number (P/N) AIR 
124792], as applicable, to detect corrosion, cracking, or damage, in 
accordance with the service bulletin. If any corrosion, cracking, or 
damage is detected during that inspection, prior to further flight, 
replace the existing bolt with a new or serviceable bolt in 
accordance with the service bulletin.
    (2) Perform a visual inspection of each MLG retract actuator 
bracket retaining bolt, Item 840 (P/N AIR 123940), to determine if 
the nut of the bolt is bottoming the threads in accordance with the 
service bulletin. If any nut bottoms the threads, prior to further 
flight, install washers in accordance with the service bulletin.
    (b) At the next MLG overhaul, or within 12,000 landings after 
the effective date of this AD, whichever occurs earlier, accomplish 
the requirements of paragraphs (b)(1) and (b)(2) of this AD in 
accordance with Paragraphs C. through F. of the Accomplishment 
Instructions of Saab Service Bulletin 340-32-094, dated October 29, 
1993, or Revision 1, dated March 4, 1994.
    (1) Perform a visual and magnaflux inspection of each MLG 
retract actuator bracket retainer bolt, Item 792A or 792 (P/N AIR 
124792), as applicable, to detect any scored, cracked, or out-of-
tolerance condition, in accordance with the service bulletin. If any 
bolt is found to be scored, cracked, or out-of-tolerance, prior to 
further flight, replace the bolt with a serviceable magnafluxed bolt 
or with a new bolt, in accordance with the service bulletin.

    Note 1: In accordance with normal maintenance practices, the 
retainer bolts also should be visually inspected for corrosion when 
they are removed during the accomplishment of the inspections 
required by this paragraph. Any corroded bolt that is detected 
should be replaced with a serviceable bolt or a new bolt. 
Instructions for performing visual inspections of the retainer bolts 
to detect corrosion are contained in Attachments 1, 2, 5, 6, and 7 
of Saab Service Bulletin 340-32-094.

    (2) Replace each existing MLG retract actuator bracket retaining 
bolt, Item 840 (P/N AIR 123940), with a new bolt, P/N AIR 134736, in 
accordance with the service bulletin.
    (c) At the next MLG overhaul, or within 12,000 landings after 
the effective date of this AD, whichever occurs earlier, remove the 
existing nose landing gear trunnion pin cross bolt, P/N NAS 1305-
54D, and replace it with a new bolt, P/N NAS 1305-50D, in accordance 
with Paragraphs C. through F. of the Accomplishment Instructions of 
Saab Service Bulletin 340-32-094, dated October 29, 1993, or 
Revision 1, dated March 4, 1994
    (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, 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 Manager, Standardization Branch, ANM-113.

    (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.
    (f) The actions shall be done in accordance with the following 
Saab service bulletins, which contain the following list of 
effective pages: 

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 Saab service bulletin and date-       Page No.-       Revision level -shown on page       Date shown on page   
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340-32-094, Oct. 29, 1993.......  Title page-.......  Original-.......................  Oct. 29, 1993.          
                                  1-5...............  (These pages are not dated.)                              
                                                                                                                
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                                                 -- Attachment 1                                                
                                                                                                                
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-                                 1-4-..............  Original-.......................  Apr. 1993.              
                                                                                                                
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                                                  Attachment 2                                                  
                                                                                                                
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                                  1-4-..............  Original-.......................  Apr. 1993.              
                                                                                                                
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                                                  Attachment 3                                                  
                                                                                                                
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                                  1-6-..............  Original-.......................  Aug. 1993.              
                                                                                                                
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                                                  Attachment 4                                                  
                                                                                                                
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                                  1-6-..............  Original-.......................  Aug. 1993.              
                                                                                                                
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                                                  Attachment 5                                                  
                                                                                                                
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                                  1, 3-.............  (These pages are not dated.)      June 1993.              
                                  2, 4..............  Original........................                          
                                                                                                                
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                                                  Attachment 6                                                  
                                                                                                                
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                                  1-4-..............  (These pages are not dated.)                              
                                                                                                                
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                                                  Attachment 7                                                  
                                                                                                                
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-                                 1-4-..............  (These pages are not dated.)                              
                                                                                                                
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                                                  Attachment 8                                                  
                                                                                                                
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-                                 1-4-..............  (These pages are not dated.)                              
                                                                                                                
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340-32-094, Revision 1, Mar. 4,   Title page-.......  1-..............................  Mar. 4, 1994. -         
 1994.                            1-6...............  1...............................  Mar. 4, 1994.           
                                                                                                                
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                                                   Attachment 1                                                 
                                                                                                                
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-                                 2, 4-.............  1-..............................  Jan. 1994.              
                                  1, 3..............  Original........................  Apr. 1993.              
                                                                                                                
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                                                  Attachment 2                                                  
                                                                                                                
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                                  2, 4-.............  1-..............................  Jan. 1994.              
                                  1, 3..............  Original........................  Apr. 1993.              
                                                                                                                
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                                                  Attachment 3                                                  
                                                                                                                
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                                  1-4, 6-7-.........  1-..............................  Jan. 1994.              
                                  5.................  Original........................  Aug. 1993.              
                                                                                                                
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                                                  Attachment 4                                                  
                                                                                                                
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                                  1-4, 6-7-.........  1-..............................  Jan. 1994.              
                                  5.................  Original........................  Aug. 1993.              
                                                                                                                
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                                                  Attachment 5                                                  
                                                                                                                
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-                                 1-5-..............  2-..............................  Jan. 1994.              
                                                                                                                
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                                                  Attachment 6                                                  
                                                                                                                
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-                                 1-5-..............  2-..............................  Jan. 1994.              
                                                                                                                
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                                                  Attachment 7                                                  
                                                                                                                
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-                                 1-5-..............  2-..............................  Jan. 1994.              
                                                                                                                
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                                                  Attachment 8                                                  
                                                                                                                
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-                                 1-5-..............  2-..............................  Jan. 1994.              
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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, Product Support, 
S581.88, 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.
    (g) This amendment becomes effective on October 11, 1994.

    Issued in Renton, Washington, on August 24, 1994.
N.B. Martenson,
 Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-21361 Filed 9-8-94; 8:45 am]
BILLING CODE 4910-13-U