Document ID: FAA-2008-1267-0003
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Viking Air Limited Model DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 Airplanes
Posted Date: 2009-02-19T05:00Z

[Federal Register: February 19, 2009 (Volume 74, Number 32)]
[Rules and Regulations]               
[Page 7641-7643]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr19fe09-1]                         

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[[Page 7641]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-1267; Directorate Identifier 2008-CE-069-AD; 
Amendment 39-15815; AD 2009-04-09]
RIN 2120-AA64

 
Airworthiness Directives; Viking Air Limited Model DHC-6-1, DHC-
6-100, DHC-6-200, and DHC-6-300 Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: We are superseding an existing airworthiness directive (AD) 
for the products listed above. This AD results from mandatory 
continuing airworthiness information (MCAI) issued by an aviation 
authority of another country to identify and correct an unsafe 
condition on an aviation product. The MCAI describes the unsafe 
condition as:

    There have been reports of inter-rivet cracking on several wing 
front spar adapter assemblies (P/N C6WM1027-1) on the horizontal and 
vertical flanges. It was determined that the cracking was caused by 
stress corrosion in the short transverse grain initiated by local 
riveting induced stresses.

We are issuing this AD to require actions to correct the unsafe 
condition on these products.

DATES: This AD becomes effective March 26, 2009.
    As of August 5, 2008 (73 FR 37353, July 1, 2008), the Director of 
the Federal Register approved the incorporation by reference of Viking 
DHC-6 Twin Otter Service Bulletins No. V6/540, dated October 1, 2007; 
No. V6/541, dated October 1, 2007; and No. V6/542, dated October 1, 
2007; and R.W. Martin, Inc. Service Bulletin No. 00160/2, Revision A, 
dated November 15, 2007, listed in this AD.

ADDRESSES: You may examine the AD docket on the Internet at http://
www.regulations.gov or in person at the Docket Management Facility, 
U.S. Department of Transportation, Docket Operations, M-30, West 
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., 
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Pong Lee, Aerospace Engineer, FAA, New 
York Aircraft Certification Office, ANE-171, 1600 Stewart Avenue, Suite 
410, Westbury, New York 11590; telephone: (516) 228-7324; fax: (516) 
794-5531.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an AD that would apply to the specified products. 
That NPRM was published in the Federal Register on December 3, 2008 (73 
FR 73618), and proposed to supersede AD 2008-11-10, Amendment 39-15532 
(73 FR 37353, July 1, 2008). That NPRM proposed to correct an unsafe 
condition for the specified products. The MCAI states that:

    There have been reports of inter-rivet cracking on several wing 
front spar adapter assemblies (P/N C6WM1027-1) on the horizontal and 
vertical flanges. It was determined that the cracking was caused by 
stress corrosion in the short transverse grain initiated by local 
riveting induced stresses. This directive mandates modification and 
inspection of the wing front spar adapter fitting and replacement of 
cracked fittings.

Since we issued AD 2008-11-10, Amendment 39-15532 (73 FR 37353, July 1, 
2008), we have added to the Applicability section additional wing box 
part numbers that may incorporate a P/N C6WM1027-1 front spar adapter 
assembly with 10 or more years of service.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We received no comments on the NPRM or on the determination of 
the cost to the public.

Conclusion

    We reviewed the available data and determined that air safety and 
the public interest require adopting the AD as proposed.

Differences Between This AD and the MCAI or Service Information

    We have reviewed the MCAI and related service information and, in 
general, agree with their substance. But we might have found it 
necessary to use different words from those in the MCAI to ensure the 
AD is clear for U.S. operators and is enforceable. In making these 
changes, we do not intend to differ substantively from the information 
provided in the MCAI and related service information.
    We might also have required different actions in this AD from those 
in the MCAI in order to follow FAA policies. Any such differences are 
highlighted in a NOTE within the AD.

Costs of Compliance

    We estimate that this AD will affect 157 products of U.S. registry. 
We also estimate that it will take about 18 work-hours per product to 
comply with the basic requirements of this AD. The average labor rate 
is $80 per work-hour. Based on these figures, we estimate the cost of 
this AD to the U.S. operators to be $226,080 or $1,440 per product.
    In addition, we estimate that any necessary follow-on actions would 
take about 200 work-hours and require parts costing $3,696, for a cost 
of $19,696 per product. We have no way of determining the number of 
products that may need these actions.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. ``Subtitle VII: Aviation 
Programs,'' describes in more detail the scope of the Agency's 
authority.
    We are issuing this rulemaking under the authority described in 
``Subtitle VII, Part A, Subpart III, Section 44701: General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on

[[Page 7642]]

products identified in this rulemaking action.

Regulatory Findings

    We determined that this AD will not have federalism implications 
under Executive Order 13132. This AD will 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.
    For the reasons discussed above, I certify this AD:
    (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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this AD and placed it in the AD Docket.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains the NPRM, the regulatory evaluation, 
any comments received, and other information. The street address for 
the Docket Office (telephone (800) 647-5527) is in the ADDRESSES 
section. Comments will be available in the AD docket shortly after 
receipt.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by removing Amendment 39-15532 (73 FR 
37353, July 1, 2008) and adding the following new AD:

2009-04-09 Viking Air Limited: Amendment 39-15815; Docket No. FAA-
2008-1267; Directorate Identifier 2008-CE-069-AD.

Effective Date

    (a) This airworthiness directive (AD) becomes effective March 
26, 2009.

Affected ADs

    (b) This AD supersedes AD 2008-11-10, Amendment 39-15532 (73 FR 
37353, July 1, 2008).

Applicability

    (c) This AD applies to the following Models DHC-6-1, DHC-6-100, 
DHC-6-200, and DHC-6-300 airplanes, all serial numbers, that are 
certificated in any category:
    (1) Group 1: Equipped with wing boxes, part numbers (P/Ns) 
C6W1002-1, C6W1002-3, WR6-1002-59 or WR6-1002-61 that incorporate a 
P/N C6WM1027-1 front spar adapter assembly with 10 or more years of 
service; and
    (2) Group 2: Equipped with wing boxes, P/Ns C6W1002-5, C6W1002-
7, C6W1002-9, C6W1002-11, C6W1002-13, C6W1002-15, C6W1002-17, 
C6W1002-19, C6W1002-21, C6W1002-23, C6W1002-51, C6W1002-53, C6W1002-
55, C6W1002-57 or C6W1002-61 that incorporate a P/N C6WM1027-1 front 
spar adapter assembly with 10 or more years of service.

Subject

    (d) Air Transport Association of America (ATA) Code 57: Wings.

Reason

    (e) The mandatory continuing airworthiness information (MCAI) 
states:

    ``There have been reports of inter-rivet cracking on several 
wing front spar adapter assemblies (P/N C6WM1027-1) on the 
horizontal and vertical flanges. It was determined that the cracking 
was caused by stress corrosion in the short transverse grain 
initiated by local riveting induced stresses. This directive 
mandates modification and inspection of the wing front spar adapter 
fitting and replacement of cracked fittings.''

Since we issued AD 2008-11-10, Amendment 39-15532 (73 FR 37353, July 
1, 2008), we have added to the Applicability section additional wing 
box part numbers that may incorporate a P/N C6WM1027-1 front spar 
adapter assembly with 10 or more years of service.

Actions and Compliance

    (f) Unless already done, do the following actions:
    (1) For Group 1 airplanes, within the next 180 days after August 
5, 2008 (the effective date of AD 2008-11-10), install inspection 
holes in the left-hand (LH) and right-hand (RH) lower wing skins 
following Viking DHC-6 Twin Otter Service Bulletin Number V6/541, 
dated October 1, 2007.
    (2) For Group 2 airplanes, within the next 180 days after the 
effective date of this AD, install inspection holes in the LH and RH 
lower wing skins following Viking DHC-6 Twin Otter Service Bulletin 
Number V6/541, dated October 1, 2007.
    (3) For Group 1 and Group 2 airplanes, before further flight 
after installing the inspection holes required in paragraph (f)(1) 
or (f)(2) of this AD, initially inspect the LH and RH front spar 
adapter assemblies for cracks, and repetitively thereafter inspect 
all affected wing box P/Ns at intervals not to exceed 1,200 hours 
time-in-service or 12 months, whichever occurs first, until the 
replacement required in paragraph (f)(4) of this AD is done.
    (i) For wing box P/Ns C6W1002-1, C6W1002-3, C6W1002-5, C6W1002-
7, C6W1002-9, C6W1002-11, C6W1002-13, C6W1002-15, C6W1002-17, 
C6W1002-19, C6W1002-21, C6W1002-23, C6W1002-51, C6W1002-53, C6W1002-
55, C6W1002-57, C6W1002-59, and C6W1002-61, inspect following Viking 
DHC-6 Twin Otter Service Bulletin Number V6/540, dated October 1, 
2007.
    (ii) For wing box P/Ns WR6-1002-59 or WR6-1002-61, inspect 
following R.W. Martin, Inc. Service Bulletin No. 00160/2, Revision 
A, dated November 15, 2007.
    (4) For Group 1 and 2 airplanes, before further flight after 
doing any inspection required in paragraph (f)(3) of this AD where 
cracks are found, replace the cracked front spar adapter assembly 
with a front spar adapter assembly, P/N C6WM1027-3. Do the 
replacement following Viking DHC-6 Twin Otter Service Bulletin 
Number V6/542, dated October 1, 2007. This replacement terminates 
the repetitive inspections required in paragraph (f)(3) of this AD 
for the replaced front spar adapter assembly.
    (5) As a terminating action for the repetitive inspections 
required in paragraph (f)(3) of this AD, at any time after the 
initial inspection required in paragraph (f)(3) of this AD, you may 
replace P/N C6WM1027-1 with P/N C6WM1027-3, except it must be 
replaced prior to further flight as required by paragraph (f)(4) of 
this AD.

FAA AD Differences

    Note: This AD differs from the MCAI and/or service information 
as follows:
    (1) MCAI Transport Canada AD No. CF-2007-31, dated December 17, 
2007, is applicable to airplane models with front spar adapter 
assembly P/N C6WM1027-3 that incorporate task C57-10-18 of the DHC-6 
Corrosion Prevention and Control Manual (CPCM), PSM 1-6-5.
    (2) The applicability of this AD does not include airplane 
models with front spar adapter assembly P/N C6WM1027-3 that 
incorporate task C57-10-18 of the DHC-6 CPCM, PSM 1-6-5, which is 
required in the Transport Canada AD No. CF-94-12R1, dated April 13, 
1999, and AD No. CF-99-11, dated May 28, 1999. We have addressed the 
Corrosion Prevention and Control Program in AD 2008-13-11 (73 FR 
37355, July 1, 2008), which identifies specific areas that must be 
inspected to ensure the structural integrity of the DHC-6 fleet.

Other FAA AD Provisions

    (g) The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager, New 
York Aircraft Certification Office, FAA, has the authority to

[[Page 7643]]

approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. Send information to ATTN: Pong Lee, Aerospace 
Engineer, FAA, New York Aircraft Certification Office, ANE-171, 1600 
Stewart Avenue, Suite 410, Westbury, New York 11590; telephone: 
(516) 228-7324; fax: (516) 794-5531. Before using any approved AMOC 
on any airplane to which the AMOC applies, notify your appropriate 
principal inspector (PI) in the FAA Flight Standards District Office 
(FSDO), or lacking a PI, your local FSDO.
    (2) Airworthy Product: For any requirement in this AD to obtain 
corrective actions from a manufacturer or other source, use these 
actions if they are FAA-approved. Corrective actions are considered 
FAA-approved if they are approved by the State of Design Authority 
(or their delegated agent). You are required to assure the product 
is airworthy before it is returned to service.
    (3) Reporting Requirements: For any reporting requirement in 
this AD, under the provisions of the Paperwork Reduction Act (44 
U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has 
approved the information collection requirements and has assigned 
OMB Control Number 2120-0056.

Related Information

    (h) Refer to MCAI Transport Canada AD No. CF-2007-31, dated 
December 17, 2007; Viking DHC-6 Twin Otter Service Bulletins No. V6/
540, dated October 1, 2007; No. V6/541, dated October 1, 2007; and 
No. V6/542, dated October 1, 2007; and R.W. Martin, Inc. Service 
Bulletin No. 00160/2, Revision A, dated November 15, 2007, for 
related information.

Material Incorporated by Reference

    (i) You must use Viking DHC-6 Twin Otter Service Bulletins No. 
V6/540, dated October 1, 2007; No. V6/541, dated October 1, 2007; 
and No. V6/542, dated October 1, 2007; and R.W. Martin, Inc. Service 
Bulletin No. 00160/2, Revision A, dated November 15, 2007, to do the 
actions required by this AD, unless the AD specifies otherwise.
    (1) On August 5, 2008 (73 FR 37353, July 1, 2008), the Director 
of the Federal Register previously approved the incorporation by 
reference of Viking DHC-6 Twin Otter Service Bulletins No. V6/540, 
dated October 1, 2007; No. V6/541, dated October 1, 2007; and No. 
V6/542, dated October 1, 2007; and R.W. Martin, Inc. Service 
Bulletin No. 00160/2, Revision A, dated November 15, 2007.
    (2) For service information identified in this AD, contact 
Viking Air Limited, 9574 Hampden Road, Sidney, B.C., Canada V8L 5V5; 
telephone: (250) 656-7227; fax: (250) 656-0673; Internet: http://
www.vikingair.com; or R.W. Martin, Inc., 37552 Winchester Road, 
Hangar 20, Murrieta, California 92563; telephone: (951) 600-0009; 
fax: (951) 600-1005; Internet: http://www.rwmi.net.
    (3) You may review copies of the service information 
incorporated by reference for this AD at the FAA, Central Region, 
Office of the Regional Counsel, 901 Locust, Kansas City, Missouri 
64106. For information on the availability of this material at the 
Central Region, call (816) 329-3768.
    (4) You may also review copies of the service information 
incorporated by reference for this AD at the National Archives and 
Records Administration (NARA). For information on the availability 
of this material at NARA, call (202) 741-6030, or go to: http://
www.archives.gov/federal_register/code_of_federal_regulations/
ibr_locations.html.

    Issued in Kansas City, Missouri, on February 6, 2009.
Kim Smith,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. E9-3115 Filed 2-18-09; 8:45 am]

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