[Federal Register Volume 61, Number 193 (Thursday, October 3, 1996)]
[Proposed Rules]
[Pages 51619-51621]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-25304]


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


DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-CE-45-AD]
RIN 2120-AA64


Airworthiness Directives, de Havilland DHC-6 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes to adopt a new airworthiness directive

[[Page 51620]]

(AD) that would apply to de Havilland DHC-6 series airplanes that do 
not have a certain wing strut modification (Modification 6/1581) 
incorporated. The proposed action would require inspecting the wing 
struts for cracks or damage (chafing, etc.), replacing wings struts 
that are found damaged beyond certain limits or are found cracked, and 
incorporating Modification No. 6/1581 to prevent future chafing damage. 
Several reports of wing strut damage caused by the upper fairing 
rubbing against the wing strut prompted the proposed action. The 
actions specified by the proposed AD are intended to prevent failure of 
the wing struts, which could result in loss of control of the airplane.

DATES: Commens must be received on or before December 5, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 93-CE-45-AD, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106. Comments may be inspected at 
this location between 8 a.m. and 4 p.m., Monday through Friday, 
holidays excepted.
    Service information that applies to the proposed AD may be obtained 
from de Havilland, Inc., 123 Garratt Boulevard, Downsview, Ontario, 
Canada, M3K 1Y5. This information also may be examined at the Rules 
Docket at the address above.

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: 

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report that summarizes each FAA-public contact concerned 
with the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 93-CE-45-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Central Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 93-CE-45-AD, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106.

Discussion

    Transport Canada, which is the airworthiness authority for Canada, 
has notified the FAA that an unsafe condition may exist on de Havilland 
DHC-6 series airplanes. Transport Canada reports that the upper fairing 
has rubbed against the wing struts on several of the above referenced 
airplanes, which has resulted in wing strut damage.

Explanation of the Relevant Service Information

    De Havilland has issued Service Bulletin (SB) No. 6/342, dated 
February 23, 1976, which specifies procedures for (1) inspecting the 
wing struts for cracks and damage (chafing, etc.); and (2) 
incorporating Modification No. 6/1581 to prevent further chafing 
damage. 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. Transport Canada classified this service bulletin 
as mandatory and issued Transport Canada AD CF-91-30, dated August 8, 
1991, in order to assure the continued airworthiness of these airplanes 
in Canada.

Evaluation of all Applicable Information

    This airplane model is manufactured in Canada and is type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, Transport Canada has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of Transport Canada; reviewed all available information, 
including the service information referenced above; and determined that 
AD action is necessary for products of this type design that are 
certificated for operation in the United States.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other de Havilland DHC-6 series airplanes of the 
same type design that do not have Modification 6/1581 incorporated, the 
proposed AD would 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. 
Accomplishment of the proposed inspection and modification would be 
required in accordance with de Havilland SB No. 6/342, dated February 
23, 1976.

FAA's Aging Commuter Aircraft Policy

    This action is consistent with the FAA/s aging commuter airplane 
policy. This policy simply states that reliance on repetitive 
inspection 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 inspection to detect damaged wing struts.

Cost Impact

    The FAA estimates that 169 airplanes in the U.S. registry would be 
affected by the proposed AD, that it would take approximately 8 
workhours per airplane to accomplish the proposed 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 proposed AD on U.S. operators is estimated to be 
$106,470. This figure is based upon the assumption 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. 
Assuming that each set of parts is incorporated on an effected 
airplane, the cost impact upon U.S. operators/owners would be reduced 
by $6,930 from $106,470 to $99,540.

[[Page 51621]]

Regulatory Impact

    The regulations proposed herein would 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 
proposal would 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) if promulgated, 
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 draft regulatory evaluation 
prepared for this action has been placed 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, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 
to read as follows:

de Havilland: 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 closet 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, 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, but does not exceed 0.25-inch in depth, does not exceed a 
total length of 5 inches, and where any two places of damage are 
separate 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) All persons affected by this directive may obtain copies of 
the document referred to herein upon request to de Havilland, Inc., 
123 Garratt Boulevard, Downsview, Ontario M3K 1Y5 Canada; or may 
examine this document at the FAA, Central Region, Office of the 
Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, 
Missouri 64106.

    Issued in Kansas City, Missouri, on September 26, 1996.
James E. Jackson,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-25304 Filed 10-2-96; 8:45 am]
BILLING CODE 4910-13-M