[Federal Register Volume 64, Number 129 (Wednesday, July 7, 1999)]
[Proposed Rules]
[Pages 36624-36626]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-17177]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-58-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-100 and -300 
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 certain Bombardier Model DHC-8-100 
and -300 series airplanes. This proposal would require modification of 
certain hydraulic systems that provide hydraulic pressure for the 
control of the rudder and for the main landing gear brakes. 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 damage to certain 
hydraulic system components in the number 2 engine nacelle, which could 
result in loss of the number 1 and number 2 hydraulic systems, and 
consequent reduced controllability of the airplane.

DATES: Comments must be received by August 6, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-58-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: Anthony Gallo, Aerospace Engineer, 
Systems and Flight Test Branch, ANE-172, FAA, Engine and Propeller

[[Page 36625]]

Directorate, New York Aircraft Certification Office, 10 Fifth Street, 
Third Floor, Valley Stream, New York 11581; telephone (516) 256-7510; 
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 97-NM-58-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. 97-NM-58-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 Bombardier Model DHC-8-100 and -300 series airplanes. 
TCA advises that it has received reports of hydraulic system damage in 
the number 2 engine nacelle caused by in-flight, fuel-fed engine fires; 
and in one incident, the complete hull of the airplane was lost. In 
each incident, the fire was caused by leaking and igniting fuel. 
However, the source of the fuel leak in each incident was a different 
source, as was the source of ignition.
    Investigation revealed that the hydraulic system did not cause the 
fire in any of the incidents, however, the damage from the fires 
resulted in a total loss of hydraulic pressure in both hydraulic 
systems 1 and 2. These hydraulic systems supply hydraulic power for the 
control of the rudder and for the main landing gear (MLG) brakes. 
Further investigation revealed that the location of the number 2 
standby power unit (SPU) and certain hydraulic components of the 
parking brake system (i.e., parking brake accumulator, charging valve, 
and viewing gauge) may have contributed to the hydraulic system damage. 
Such damage, if not corrected, could result in loss of the number 1 and 
number 2 hydraulic systems, and consequent reduced controllability of 
the airplane.

Explanation of Relevant Service Information

    Bombardier has issued the following service bulletins which 
describe procedures for modification of certain hydraulic systems that 
provide hydraulic pressure for the control of the rudder and for the 
main landing gear brakes:
    Bombardier Service Bulletin S.B. 8-32-128, Revision `C,' dated 
March 27, 1998, describes procedures for modification of the parking 
brake accumulator and charging valve of the parking brake system. This 
service bulletin is divided into two parts, A and B, respectively.
    Part A of the Accomplishment Instructions (Bombardier Modification 
8/1982) is applicable to airplanes on which Bombardier Modification 8/
1152 has been installed. Part A of the Accomplishment Instructions 
describes procedures for relocation of the parking brake charging valve 
from the number 2 engine nacelle to the right-hand wing root, 
modification of the wing root and installation of a new front access 
panel, support, cleat, and associated hydraulic tubes.
    Part B of the Accomplishment Instructions (Bombardier Modifications 
8/1152 and 8/1982) is applicable to airplanes on which Bombardier 
Modification 8/1152 has not been installed. Part B of the 
Accomplishment Instructions describes procedures for relocation of the 
parking brake accumulator, charging valve, and viewing gauge; and 
installation of a new support assembly, panel assembly, viewing port, 
and tube assemblies in the right-hand wing root.
    Bombardier Service Bulletin S.B. 8-29-23, dated December 6, 1996, 
describes procedures for relocation of the number 2 SPU of the number 2 
engine nacelle to the rear fuselage; and installation of a new support 
assembly, hydraulic isolation valve, tube assemblies, wiring, circuit 
breaker, caution indicator, and associated relays.
    Bombardier Service Bulletin S.B. 8-29-29, dated February 27, 1998, 
describes procedures for installation of a hydraulic rudder isolation 
system that involves installation of two new hydraulic isolation 
valves, electrical wiring, caution lights, and tube assemblies. 
Accomplishment of Service Bulletin S.B. 8-29-29 is an alternative to 
the modification described in Service Bulletin S.B. 8-29-23.
    Accomplishment of the actions specified in these service bulletins 
is intended to adequately address the identified unsafe condition. TCA 
has approved these service bulletins and issued Canadian airworthiness 
directives CF-96-25R1, dated January 16, 1997, and CF-96-25R2, dated 
September 10, 1998, 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 
Sec. 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 bulletins described previously.

Cost Impact

    The FAA estimates that 148 airplanes of U.S. registry would be 
affected by this proposed AD.
    For airplanes identified in Bombardier Service Bulletin S.B. 8-32-
128, Revision `C,' it would take between 15 and 40 work hours per 
airplane to accomplish the proposed modification, at an average labor 
rate of $60 per work hour. Required parts would be provided by the 
manufacturer at no cost to the

[[Page 36626]]

operators. Based on these figures, the cost impact of the modification 
proposed by this AD on U.S. operators is estimated to be between 
$133,200 and $355,200, or between $900 and $2,400 per airplane.
    For airplanes identified in Bombardier Service Bulletin S.B. 8-29-
23, it would take approximately 346 work hours per airplane to 
accomplish the proposed relocation, at an average labor rate of $60 per 
work hour. Required parts would be provided by the manufacturer at no 
cost to the operators. Based on these figures, the cost impact of the 
modification proposed by this AD on U.S. operators is estimated to be 
$3,072,480, or $20,760 per airplane.
    For airplanes identified in Bombardier Service Bulletin S.B. 8-29-
29, it would take approximately 120 work hours per airplane to 
accomplish the proposed installation, at an average labor rate of $60 
per work hour. Required parts would be provided by the manufacturer at 
no cost to the operators. Based on these figures, the cost impact of 
the installation proposed by this AD on U.S. operators is estimated to 
be $1,065,600, or $7,200 per airplane.
    The cost impact figures discussed above are 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:

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket 97-NM-58-AD.
    Applicability: Model DHC-8-100 and -300 series airplanes having 
serial numbers 003 through 405; except those airplanes on which 
Bombardier Modifications 8/1152 and 8/1982 have been installed, and 
on which either Bombardier Modification 8/1983 or 8/2781 has 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 
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 damage to certain hydraulic system components in the 
number 2 engine nacelle, which could result in loss of the number 1 
and number 2 hydraulic systems, and consequent reduced 
controllability of the airplane, accomplish the following:
    (a) Within 18 months after the effective date of this AD, modify 
certain hydraulic systems that provide hydraulic pressure for the 
control of the rudder and for the main landing gear brakes by 
accomplishing the requirements of paragraph (a)(1) or (a)(2), as 
applicable, in accordance with Bombardier Service Bulletin S.B. 8-
32-128, Revision `C,' dated March 27, 1998.
    (1) For all airplanes on which Bombardier Modification 8/1152 
has been installed: Accomplish Part A of the Accomplishment 
Instructions of the service bulletin.
    (2) For all airplanes on which Bombardier Modification 8/1152 
has not been installed: Accomplish Part B of the Accomplishment 
Instructions of the service bulletin.
    (b) Within 18 months after the effective date of this AD, 
accomplish the actions specified in either paragraph (b)(1) or 
(b)(2) of this AD.
    (1) Relocate the number 2 standby power unit (SPU) of the number 
2 hydraulic system in accordance with Bombardier Service Bulletin 
S.B. 8-29-23, dated December 6, 1996; or
    (2) Install a hydraulic rudder isolation system in the number 1 
and number 2 hydraulic systems in accordance with Bombardier Service 
Bulletin S.B. 8-29-29, dated February 27, 1998.
    (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 directives CF-96-25R1, dated January 16, 1997, and CF-
96-25R2, dated September 10, 1998.

    Issued in Renton, Washington, on June 30, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-17177 Filed 7-6-99; 8:45 am]
BILLING CODE 4910-13-P