[Federal Register Volume 62, Number 62 (Tuesday, April 1, 1997)]
[Rules and Regulations]
[Pages 15373-15375]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-8249]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-CE-45-AD; Amendment 39-9984; AD 97-07-10]
RIN 2120-AA64


Airworthiness Directives; De Havilland DHC-6 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
applies to de Havilland DHC-6 series airplanes that do not have a 
certain wing strut modification (Modification 6/1581) incorporated. 
This action requires inspecting the wing struts for cracks or damage 
(chafing, etc.), replacing wing struts that are found damaged beyond 
certain limits or are found cracked, and incorporating Modification No. 
6/1581 to prevent future chafing damage. This AD results from several 
reports of wing strut damage caused by the upper fairing rubbing 
against the wing strut. The actions specified by this AD are intended 
to prevent failure of the wing struts, which could result in loss of 
control of the airplane.

DATES: Effective May 23, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 23, 1997.

ADDRESSES: Service information that applies to this AD may be obtained 
from de Havilland, Inc., 123 Garratt Boulevard, Downsview, Ontario, 
Canada, M3K 1Y5. This information may also be examined at the Federal 
Aviation Administration (FAA), Central Region, Office of the Assistant 
Chief Counsel, Attention: Rules Docket 93-CE-45-AD, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106; or at the Office of the 
Federal Register, 800 North Capitol Street, NW., suite 700, Washington, 
DC.

FOR FURTHER INFORMATION CONTACT: Jon Hjelm, Aerospace Engineer, FAA, 
New York Aircraft Certification Office, 10 Fifth Street, 3rd Floor, 
Valley Stream, New York 11581; telephone (516) 256-7523; facsimile 
(516) 568-2716.

SUPPLEMENTARY INFORMATION:

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to include an AD that would apply to de Havilland DHC-6 
series airplanes that do not have a certain wing strut modification 
(Modification 6/1581) incorporated was published in the Federal 
Register as a notice of proposed rulemaking (NPRM) on October 3, 1996 
(61 FR 51619). The NPRM proposed to require inspecting the wing struts 
for cracks or damage (chafing, etc.), replacing wing struts that are 
found damaged beyond certain limits or are found cracked, and 
incorporating Modification No. 6/1581 to prevent future chafing damage. 
Modification No. 6/1581 consists of installing a preformed nylon shield 
around the area of each wing strut of the upper end closest to the 
wing. Accomplishment of the proposed inspection and modification as 
specified in the NPRM would be required in accordance with de Havilland 
Service Bulletin No. 6/342, dated February 23, 1976.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were received on the 
proposed rule or the FAA's determination of the cost to the public.

The FAA's Determination

    After careful review of all available information related to the 
subject presented above, the FAA has determined that air safety and the 
public interest require the adoption of

[[Page 15374]]

the AD as proposed except for minor editorial corrections. The FAA has 
determined that these minor corrections will not change the meaning of 
the AD and will not add any additional burden upon the public than was 
already proposed.

FAA's Aging Commuter Aircraft Policy

    This AD is consistent with the FAA's aging commuter airplane 
policy. This policy simply states that reliance on repetitive 
inspections of critical areas on airplanes utilized in commuter service 
carries an unnecessary safety risk when a design change exists that 
could eliminate or, in certain instances, reduce the number of those 
critical inspections. The alternative to incorporating Modification No. 
6/1581 on de Havilland DHC-6 series airplanes would be relying on 
repetitive inspections to detect damaged wing struts.

Cost Impact

    The FAA estimates that 169 airplanes in the U.S. registry will be 
affected by this AD, that it will take approximately 8 workhours per 
airplane to accomplish the required action, and that the average labor 
rate is approximately $60 an hour. Parts cost approximately $150 per 
airplane. Based on these figures, the total cost impact of the AD on 
U.S. operators is estimated to be $106,470. This figure is based upon 
the presumption that no affected airplane owner/operator has 
incorporated Modification No. 6/1581.
    De Havilland has informed the FAA that enough parts have been 
distributed to equip approximately 11 of the affected airplanes. 
Presuming that each set of parts is incorporated on an affected 
airplane, the cost impact upon U.S. operators/owners would be reduced 
by $6,930 from $106,470 to $99,540.

Regulatory Impact

    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 copy of the final 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, 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 a new airworthiness directive 
(AD) to read as follows:

97-07-10 Dehavilland: Amendment 39-9984; Docket No. 93-CE-45-AD.

    Applicability: Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-
300 airplanes (all serial numbers), certificated in any category, 
that do not have Modification No. 6/1581 incorporated.

    Note 1: Modification No. 6/1581 consists of installing a 
preformed nylon shield around the area of each wing strut at the 
upper end closest to the wing.
    Note 2: 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 (d) 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 already accomplished.
    To prevent failure of the wing struts, which could result in 
loss of control of the airplane, accomplish the following:
    (a) Within the next 100 hours time-in-service (TIS) after the 
effective date of this AD, inspect the wing struts, part number (P/
N) C6W1005 (or FAA-approved equivalent), for cracks or damage 
(chafing, etc.) in accordance with the ACCOMPLISHMENT INSTRUCTIONS 
section of de Havilland Service Bulletin (SB) No. 6/342, dated 
February 23, 1976.
    (1) If damage is found on a wing strut that exceeds 0.025-inch 
in depth, exceeds a total length of 5 inches, or where any two 
places of damage are separated by less than 10 inches of undamaged 
surface over the length of the strut, prior to further flight, 
replace the wing strut with an airworthy FAA-approved part in 
accordance with the applicable maintenance manual.
    (2) If any crack is found, prior to further flight, replace the 
wing strut with an airworthy FAA-approved part in accordance with 
the applicable maintenance manual.
    (3) If damage is found on a wing strut that exceeds 0.010-inch 
in depth, provided the damage does not exceed 0.025-inch in depth, 
the damage does not exceed a total length of 5 inches, and where any 
two places of damage are separated by a minimum of 10 inches 
undamaged surface over the length of the strut, within 500 hours TIS 
after the inspection specified in paragraph (a) of this AD, replace 
the wing strut with an airworthy FAA-approved part in accordance 
with the applicable maintenance manual.
    (b) Within the next 600 hours TIS after the effective date of 
this AD, incorporate Modification No. 6/1581 in accordance with the 
ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB No. 6/342, 
dated February 23, 1976.
    (1) Incorporating Modification No. 6/1581 eliminates the 
repetitive inspection requirement of this AD.
    (2) Incorporating Modification No. 6/1581 may be accomplished at 
any time prior to 600 hours TIS after the effective date of this AD, 
at which time it must be incorporated.
    (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) An alternative method of compliance or adjustment of the 
compliance times that provides an equivalent level of safety may be 
approved by the Manager, New York Aircraft Certification Office 
(ACO), FAA, 10 Fifth Street, 3rd Floor, Valley Stream, New York 
11581. The request shall be forwarded through an appropriate FAA 
Maintenance Inspector, who may add comments and then send it to the 
Manager, New York ACO.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the New York ACO.

    (e) The inspections and modification required by this AD shall 
be done in accordance de Havilland Service Bulletin No. 6/342, dated 
February 23, 1976. 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 de Havilland, 
Inc., 123 Garratt Boulevard, Downsview, Ontario M3K 1Y5 Canada. 
Copies may be inspected at the FAA, Central Region, Office of the 
Assistant Chief Counsel,

[[Page 15375]]

Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.
    (f) This amendment (39-9984) becomes effective on May 23, 1997.

    Issued in Kansas City, Missouri, on March 26, 1997.
James E. Jackson,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-8249 Filed 3-31-97; 8:45 am]
BILLING CODE 4910-13-U