Document ID: FAA-2008-0368-0004
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Viking Air Limited Models DHC-6-1, DHC- 6-100, DHC-6-200, and DHC-6-300 Airplanes
Posted Date: 2008-07-01T04:00Z

[Federal Register: July 1, 2008 (Volume 73, Number 127)]
[Rules and Regulations]               
[Page 37353-37355]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr01jy08-1]                         

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[[Page 37353]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0368 Directorate Identifier 2008-CE-007-AD; 
Amendment 39-15532; AD 2008-11-10]
RIN 2120-AA64

 
Airworthiness Directives; Viking Air Limited Models 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.

-----------------------------------------------------------------------

SUMMARY: We are adopting a new 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 August 5, 2008.
    On August 5, 2008, the Director of the Federal Register approved 
the incorporation by reference of certain publications listed in this 
AD.

ADDRESSES: You may examine the AD docket on the Internet at http://
www.regulations.gov or in person at Document 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, 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 March 31, 2008 (73 
FR 16782). That NPRM proposed to correct an unsafe condition for the 
specified products. The 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.

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 on U.S. 
operators to be $226,080 or $1,440 per product.
    In addition, we estimate that any necessary follow-on actions will 
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 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

[[Page 37354]]

    (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 adding the following new AD:

2008-11-10 Viking Air Limited: Amendment 39-15532; Docket No. FAA-
2008-0368; Directorate Identifier 2008-CE-007-AD.

Effective Date

    (a) This airworthiness directive (AD) becomes effective August 
5, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Models DHC-6-1, DHC-6-100, DHC-6-200, and 
DHC-6-300 airplanes, all serial numbers, that are:
    (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) Certificated in any category.

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.

Actions and Compliance

    (f) Unless already done, do the following actions:
    (1) Within the next 180 days after August 5, 2008 (the effective 
date of this AD), 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) Before further flight after installing the inspection holes 
required in paragraph (f)(1) of this AD, inspect the LH and RH front 
spar adapter assemblies for cracks. For wing box P/Ns C6W1002-1 and 
C6W1002-3, inspect following Viking DHC-6 Twin Otter Service 
Bulletin Number V6/540, dated October 1, 2007. For wing box P/Ns 
WR6-1002-59 and WR6-1002-61, inspect following R.W. Martin, Inc. 
Service Bulletin No. 00160/2, Revision A, dated November 15, 2007. 
Repetitively inspect all affected wing box P/Ns thereafter at 
intervals not to exceed 1,200 hours time-in-service or 12 months, 
whichever occurs first, until the replacement required in paragraph 
(f)(3) of this AD is done.
    (3) Before further flight after doing any inspection required in 
paragraph (f)(2) 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)(2) of this AD for the replaced front spar adapter 
assembly.
    (4) As a terminating action for the repetitive inspections 
required in paragraph (f)(2) of this AD, at any time after the 
initial inspection required in paragraph (f)(2) of this AD, you may 
replace P/N C6WM1027-1 with P/N C6WM1027-3.

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, requires incorporating task C57-10-18 of the DHC-
6 Corrosion Prevention and Control Manual (CPCM), PSM 1-6-5, within 
90 days after the effective date of this AD.

    (2) We are not incorporating task C57-10-18 of the DHC-6 CPCM, 
PSM 1-6-5, into this AD because we are currently examining Transport 
Canada AD No. CF-94-12R1, dated April 13, 1999, and AD No. CF-99-11, 
dated May 28, 1999. Transport Canada issued these ADs to incorporate 
a Corrosion Prevention and Control Program that 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 
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, 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 Bulletin No. 
V6/540, dated October 1, 2007; Viking DHC-6 Twin Otter Service 
Bulletin No. V6/541, dated October 1, 2007; Viking DHC-6 Twin Otter 
Service Bulletin 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) The Director of the Federal Register approved the 
incorporation by reference of this service information under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (2) For service information identified in this AD, contact 
Viking Air Limited, 9574 Hampden Road, Sidney, B.C., Canada V8L 5V5 
or R.W. Martin, Inc., 37552 Winchester Road, Hangar 20, Murrieta, 
California 92563.

[[Page 37355]]

    (3) You may review copies at the FAA, Central Region, Office of 
the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri 
64106; or 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/cfr/ibr-locations.html.

    Issued in Kansas City, Missouri, on May 15, 2008.
David R. Showers,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-13844 Filed 6-30-08; 8:45 am]

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