[Federal Register Volume 59, Number 78 (Friday, April 22, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-9727]


[[Page Unknown]]

[Federal Register: April 22, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 94-NM-19-AD]

 

Airworthiness Directives; De Havilland Model DHC-7 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all de Havilland Model DHC-7 
series airplanes. This proposal would require removal of the aluminum 
or brass hardware in the firewall terminal block assembly and 
replacement with steel hardware. This proposal is prompted by the 
results of an investigation, which revealed that corroded aluminum 
washers in the DC firewall terminal block assembly may loosen the 
electrical connections. The actions specified by the proposed AD are 
intended to prevent interruption of DC electrical power due to 
connections that may have loosened from corrosion.

DATES: Comments must be received by June 3, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-19-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9 a.m. and 3 p.m., Monday through Friday, except Federal 
holidays.
    The service information referenced in the proposed rule may be 
obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, 
Garratt Boulevard, Downsview, Ontario M3K 1Y5 Canada. This information 
may be examined at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the FAA Engine and Propeller 
Directorate, New York Aircraft Certification Office, 181 South Franklin 
Avenue, room 202, Valley Stream, New York.

FOR FURTHER INFORMATION CONTACT: Peter Cuneo, Electrical Engineer, 
Systems and Equipment Branch, ANE-173, FAA, Engine and Propeller 
Directorate, New York Aircraft Certification Office, 181 South Franklin 
Avenue, room 202, Valley Stream, New York 11581; telephone (516) 791-
6427; fax (516) 791-9024.

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 shall 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 summarizing 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 Number 94-NM-19-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, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 94-NM-19-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    Transport Canada Aviation, which is the airworthiness authority for 
Canada, recently notified the FAA that an unsafe condition may exist on 
all de Havilland Model DHC-7 series airplanes. Transport Canada 
Aviation advises that the results of an investigation revealed that 
aluminum washers used in the DC firewall terminal block assembly of all 
Model DHC-7 series airplanes could cause corrosion at the electrical 
connections. Such corrosion could either loosen a connection and/or 
generate a high electrical resistance at the connection points. This 
condition, if not corrected, could result in interruption of DC 
electrical power due to connections that may have loosened from 
corrosion.
    Bombardier, Inc., has issued de Havilland Service Bulletin S.B. 7-
24-69, dated October 8, 1993, that describes procedures for removal of 
the aluminum or brass hardware in the firewall terminal block assembly 
and replacement with steel hardware (Modification 7/2617). Transport 
Canada Aviation classified this service bulletin as mandatory and 
issued Canadian Airworthiness Directive CF-93-30, dated December 17, 
1993, in order to assure the continued airworthiness of these airplanes 
in Canada.
    This airplane model is manufactured in Canada and is type 
certificated for operation in the United States under the provisions of 
Sec. 21.29 of the Federal Aviation Regulations and the applicable 
bilateral airworthiness agreement. Pursuant to this bilateral 
airworthiness agreement, Transport Canada Aviation has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of Transport Canada Aviation, reviewed all available 
information, and determined that AD action is necessary for products of 
this type design that are certificated for operation in the United 
States.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, the proposed AD would require removal of the 
aluminum or brass hardware in the firewall terminal block assembly and 
replacement with steel hardware (Modification 7/2617). The actions 
would be required to be accomplished in accordance with the service 
bulletin described previously.
    The FAA estimates that 55 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 3 work 
hours per airplane to accomplish the proposed actions, and that the 
average labor rate is $55 per work hour. Required parts would be 
nominal in cost. Based on these figures, the total cost impact of the 
proposed AD on U.S. operators is estimated to be $9,075, or $165 per 
airplane.
    The total cost impact figure discussed above is based on 
assumptions that no operator has yet accomplished any of the proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    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 proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the 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 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, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 14 
CFR part 39 of the Federal Aviation Regulations 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.


Sec. 39.13  [Amended]

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

De Havilland, Inc.: Docket 94-NM-19-AD.

    Applicability: All Model DHC-7 series airplanes, certificated in 
any category.
    Compliance: Required as indicated, unless accomplished 
previously. To prevent interruption of DC electrical power due to 
connections that may have loosened from corrosion, accomplish the 
following:
    (a) Within 60 days after the effective date of this AD, remove 
the aluminum or brass hardware in the firewall terminal block 
assembly and replace with steel hardware (Modification 7/2617), in 
accordance with de Havilland Service Bulletin S.B. 7-24-69, dated 
October 8, 1993.
    (b) 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, New York Aircraft Certification 
Office (ACO), FAA, Engine and Propeller Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, New York ACO.

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

    (c) Special flight permits may be issued in accordance with 
Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the 
airplane to a location where the requirements of this AD can be 
accomplished.

    Issued in Renton, Washington, on April 18, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-9727 Filed 4-21-94; 8:45 am]
BILLING CODE 4910-13-U