[Federal Register Volume 60, Number 113 (Tuesday, June 13, 1995)]
[Rules and Regulations]
[Pages 31063-31065]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-14050]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-104-AD; Amendment 39-9262; AD 95-12-12]


Airworthiness Directives; de Havilland Model DHC-8-102, -103, and 
-106 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain de Havilland Model DHC-8-102, -103, and -106 
series airplanes. This action requires repetitive operational testing 
of the stall warning computers to ensure activation of the associated 
stick shakers, and replacement of non-operational stall warning 
computers with new or serviceable units. This action also provides an 
optional terminating action for the repetitive operational tests. This 
amendment is prompted by a report that, during a routine test, the 
stick shakers of the stall warning system did not activate, due to 
contamination of the weight-on-wheels contacts in the stall warning 
computer. The actions specified in this AD are intended to ensure that 
such contamination is detected. Contamination of the stall warning 
computers could lead to incorrect logic detection of the weight-on-
wheels signal, and subsequent loss of the stick shaker function.

DATES: Effective on June 28, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 28, 1995.
    Comments for inclusion in the Rules Docket must be received on or 
before August 14, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-104-AD, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056.
    The service information referenced in this AD 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, New York Aircraft Certification 
Office, Engine and Propeller Directorate, 10 Fifth Street, Third Floor, 
Valley Stream, New York; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Peter Cuneo, Aerospace Engineer, 
Systems and Equipment Branch, ANE-172, FAA, New York Aircraft 
Certification Office, Engine and Propeller Directorate, 10 Fifth 
Street, Third Floor, Valley Stream, New York 11581; telephone (516) 
256-7506; fax (516) 568-2716.

SUPPLEMENTARY INFORMATION: Transport Canada Aviation, which is the 
airworthiness authority for Canada, recently notified the FAA that an 
unsafe condition may exist on certain de Havilland Model DHC-8-102, -
103, and -106 series airplanes equipped with Safe Flight stall warning 
computers having part number (P/N) 3605-4, -5, or -6, and on which 
Modification 8/2072 has not been installed. Transport Canada Aviation 
advises that, during a routine ``air mode'' test of the stall warning 
system, the stick shakers did not activate. Investigation revealed that 
the weight-on-wheels relay contacts within the stall warning computer 
had become contaminated. This condition, if not corrected, could lead 
to incorrect logic detection of the weight-on-wheels signal, and 
subsequent loss of the stick shaker function.
    Bombardier has issued Alert Service Bulletin S.B. A8-27-73, dated 
November 25, 1993, which describes procedures for repetitive 
operational testing to ensure activation of the stick shakers of the 
No. 1 and No. 2 stall warning computers, and replacement of non-
operational stall warning computers with new or serviceable units. 
Transport Canada Aviation classified the alert service bulletin as 
mandatory and issued Canadian airworthiness directive CF-95-06, dated 
April 10, 1995, in order to assure the continued airworthiness of these 
airplanes in Canada.
    Bombardier has also issued Service Bulletin S.B. 8-27-76, dated 
October 31, 1994, which describes procedures for replacing Safe Flight 
stall warning computers having P/N 3506-5, -6, or -7 with new stall 
warning computers having P/N 3506-8 (Modification 8/2072). The new 
stall warning computers have additional internal monitoring; 
installation of the new computers will increase reliability. 
Accomplishment of this replacement would eliminate the need for the 
repetitive operational tests.
    This airplane model is manufactured in Canada and is type 
certificated for operation in the United States under the 
[[Page 31064]] 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 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, this AD is being issued to detect contamination 
of the weight-on-wheels relay contacts in the stall warning computer; 
such contamination could lead to incorrect logic detection of the 
weight-on-wheels signal, and subsequent loss of the stick shaker 
function. This AD requires repetitive operational testing of the No. 1 
and No. 2 stall warning computers to ensure activation of the 
associated stick shaker, and replacement of non-operational stall 
warning computers with new units. This AD also provides an optional 
terminating action for the repetitive operational test requirements. 
The actions are required to be accomplished in accordance with the 
service bulletins described previously.
    The FAA is considering further rulemaking action to require the 
replacement of Safe Flight stall warning computers with units having P/
N 3506-8. However, the proposed compliance time (6 months) for this 
replacement is sufficiently long so that notice and time for public 
comment would be practicable.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been included in this rule to clarify this long-standing requirement.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 95-NM-104-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from 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 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:

95-12-12  de Havilland, Inc.: Amendment 39-9262. Docket 95-NM-104-
AD.

    Applicability: Model DHC-8-102, -103, and -106 series airplanes, 
serial numbers 003 and subsequent; equipped with Safe Flight stall 
warning computers having part number (P/N) 3605-4, -5, or -6; and on 
which Modification 8/2072 has not been installed; certificated in 
any category.

    Note 1: 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 use the authority 
provided in paragraph (c) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition; or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
[[Page 31065]] case does the presence of any modification, 
alteration, or repair remove any airplane from the applicability of 
this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent incorrect logic detection of the weight-on-wheels 
signal, and subsequent loss of the stick shaker function, accomplish 
the following:
    (a) Within 50 hours time-in-service after the effective date of 
this AD, unless previously accomplished within the last 400 hours 
time-in-service: Perform an operational test to determine activation 
of the stick shakers of the No. 1 and No. 2 stall warning computers, 
in accordance with Bombardier Alert Service Bulletin S.B. A8-27-73, 
dated November 25, 1993. Thereafter, repeat the operational test at 
intervals not to exceed 450 hours time-in-service. If any stick 
shaker does not activate, prior to further flight, replace the non-
operational stall warning computer with a new or serviceable unit in 
accordance with the alert service bulletin.
    (b) Replacement of stall warning computers having part number 
(P/N) 3605-5, -6, or -7 with new stall warning computers having P/N 
3605-8, in accordance with Bombardier Service Bulletin S.B. 8-27-76, 
dated October 31, 1994, constitutes terminating action for the 
repetitive operational test requirements of this AD.
    (c) 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the New York ACO.

    (d) 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.
    (e) The operational test and replacement shall be done in 
accordance with Bombardier Alert Service Bulletin S.B. A8-27-73, 
dated November 25, 1993, and Bombardier Service Bulletin 8-27-76, 
dated October 31, 1994. 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 Bombardier, 
Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, 
Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, New York Aircraft Certification Office, 
Engine and Propeller Directorate, 10 Fifth Street, Third Floor, 
Valley Stream, New York; or at the Office of the Federal Register, 
800 North Capitol Street NW., suite 700, Washington, DC.
    (f) This amendment becomes effective on June 28, 1995.

    Issued in Renton, Washington, on June 2, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-14050 Filed 6-12-95; 8:45 am]
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