[Federal Register Volume 63, Number 63 (Thursday, April 2, 1998)]
[Proposed Rules]
[Pages 16169-16170]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-8576]



[[Page 16169]]

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-60-AD]
RIN 2120-AA64


Airworthiness Directives; de Havilland Model DHC-8-311 and -315 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain de Havilland Model DHC-8-
311 and -315 series airplanes. This proposal would require replacement 
of the nitrogen cylinder assemblies that inflate the airplane's 
ditching dams with improved nitrogen cylinder assemblies. This proposal 
is prompted by issuance of mandatory continuing airworthiness 
information by a foreign civil airworthiness authority. The actions 
specified by the proposed AD are intended to prevent failure of the 
ditching dams to inflate fully during an emergency water landing, which 
could result in water entering the airplane.

DATES: Comments must be received by May 4, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-60-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9:00 a.m. and 3:00 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, 10 Fifth Street, 
Third Floor, Valley Stream, New York.

FOR FURTHER INFORMATION CONTACT: Ezra Sasson, Aerospace Engineer, 
Systems and Flight Test Branch, ANE-172, FAA, Engine and Propeller 
Directorate, New York Aircraft Certification Office, 10 Fifth Street, 
Third Floor, Valley Stream, New York 11581; telephone (516) 256-7520; 
fax (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 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 98-NM-60-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-114, Attention: Rules 
Docket No. 98-NM-60-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    Transport Canada Aviation (TCA), which is the airworthiness 
authority for Canada, notified the FAA that an unsafe condition may 
exist on certain de Havilland Model DHC-8-311 and -315 series airplanes 
on which the medium and high gross weight configuration is 
incorporated. This airplane model is equipped with ditching dams to 
prevent water from entering the airplane in the event of an emergency 
water landing. A nitrogen cylinder assembly is intended to inflate the 
ditching dams in fewer than six seconds. TCA advises that, during 
functional testing of ditching dams on Model DHC-8-300 series 
airplanes, some of the dams failed to inflate fully. The manufacturer 
also reported several incidents in which the nitrogen cylinder assembly 
failed to inflate the ditching dam. Such failures have been attributed 
to a problem with the design of the nitrogen cylinder assembly, in 
which excessive back pressure in the inflation valve assembly allows 
some of the gas to escape during inflation of the ditching dam. This 
condition, if not corrected, could lead to failure of the ditching dams 
to inflate fully during an emergency water landing, which could result 
in water entering the airplane.

Explanation of Relevant Service Information

    The manufacturer has issued Bombardier Service Bulletin S.B. 8-25-
122, dated October 10, 1997, which describes procedures for replacing 
the existing nitrogen cylinder assemblies on ditching dams with new 
nitrogen cylinder assemblies that incorporate an improved valve 
assembly. Accomplishment of the actions specified in the service 
bulletin is intended to adequately address the identified unsafe 
condition. TCA classified this service bulletin as mandatory and issued 
Canadian airworthiness directive CF-97-21, dated November 13, 1997, in 
order to assure the continued airworthiness of these airplanes in 
Canada.

FAA's Conclusions

    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, TCA has kept the FAA informed of the 
situation described above. The FAA has examined the findings of TCA, 
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.

Explanation of Requirements of Proposed Rule

    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 accomplishment of 
the actions specified in the service bulletin described previously.

Cost Impact

    The FAA estimates that 2 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 4 work 
hours per

[[Page 16170]]

airplane to accomplish the proposed modification, and that the average 
labor rate is $60 per work hour. Required parts would be provided by 
the manufacturer of the nitrogen cylinder assembly at no cost to the 
operator. Based on these figures, the cost impact of the proposed AD on 
U.S. operators is estimated to be $480, or $240 per airplane.
    The 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.

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 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 
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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

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

De Havilland Inc.: Docket 98-NM-60-AD.

    Applicability: Model DHC-8-311 and -315 series airplanes in the 
medium and high gross weight configuration, on which Bombardier 
Change Request CR803SO00001, CR803SO00002, CR803CH00046, 
CR803CH00079, CR803CH00105, CR825CH00847, or CR803CH00051 has been 
incorporated; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 (c) 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 accomplished 
previously.
    To prevent failure of the ditching dams to inflate fully during 
an emergency water landing, which could result in water entering the 
airplane, accomplish the following:
    (a) Within 6 months after the effective date of this AD, replace 
the existing nitrogen cylinder assembly on the ditching dams with a 
new nitrogen cylinder assembly that incorporates an improved valve 
assembly (reference de Havilland Modification 8/3154), in accordance 
with Bombardier Service Bulletin S.B. 8-25-122, dated October 10, 
1997.
    (b) As of the effective date of this AD, no person shall install 
on any airplane any nitrogen cylinder assembly having part number 
410870(BSC) or 410870-1.
    (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.

    Note 3: The subject of this AD is addressed in Canadian 
airworthiness directive CF-97-21, dated November 13, 1997.

    Issued in Renton, Washington, on March 25, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-8576 Filed 4-1-98; 8:45 am]
BILLING CODE 4910-13-U