[Federal Register Volume 68, Number 196 (Thursday, October 9, 2003)]
[Proposed Rules]
[Pages 58283-58285]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-25590]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 68, No. 196 / Thursday, October 9, 2003 / 
Proposed Rules  

[[Page 58283]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-266-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-102, -103, -106, 
-201, -202, -301, -311, and -315 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Bombardier DHC-8-
102, -103, -106, -201, -202, -301, -311, and -315 airplanes, that 
currently requires inspections to detect breakage in the struts of the 
rear mount strut assemblies on the left and right engine nacelles, and 
replacement of any broken struts. The existing AD also requires 
eventual replacement of all currently installed struts with new and/or 
reworked struts, as terminating action for the inspections. This action 
would require new repetitive inspections of the strut assemblies for 
cracking of struts replaced per the existing AD, and replacement of any 
cracked strut with a new, machined strut. This action also would change 
the applicability of the existing AD by adding certain airplanes and 
removing certain other airplanes, and would include an optional 
terminating action for the repetitive inspections. The actions 
specified by the proposed AD are intended to prevent failure of the 
engine rear mount struts, which could result in reduced structural 
integrity of the nacelle and engine support structure. This action is 
intended to address the identified unsafe condition.

DATES: Comments must be received by November 10, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-266-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-266-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 or 2000 or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Bombardier, Inc., Bombardier Regional Aircraft Division, 
123 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, 10 Fifth Street, Third Floor, Valley 
Stream, New York.

FOR FURTHER INFORMATION CONTACT: Jon Hjelm, Aerospace Engineer, 
Airframe Branch, ANE-171, FAA, New York Aircraft Certification Office, 
10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone 
(516) 256-7523; 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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
    [sbull] Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2001-NM-266-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. 2001-NM-266-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On February 14, 1994, the FAA issued AD 94-04-09, amendment 39-8829 
(59 FR 8393, February 22, 1994), applicable to certain Bombardier Model 
DHC-8-100 and DHC-8-300 airplanes, to require inspections to detect 
breakage in the engine rear mount strut assemblies, and replacement of 
broken struts. That AD also requires eventual replacement of all 
currently installed struts with new and/or reworked struts, as 
terminating action for the inspections. That action was prompted by 
several reports of failure of the engine rear mount struts, due to 
fracture at one of the rosette welds on the shank of the strut where 
full weld depth was not achieved during manufacture. The requirements 
of that AD are intended to prevent failure of the engine rear mount 
struts, which could reduce the structural integrity of the nacelle and 
engine support structure.

[[Page 58284]]

Actions Since Issuance of Previous Rule

    Since the issuance of AD 94-04-09, we have been advised by 
Transport Canada Civil Aviation (TCCA), which is the airworthiness 
authority for Canada, of reports from the manufacturer and operators of 
Model DHC-8-100 and DHC-8-300 airplanes indicating that replacement 
struts installed per that AD have developed cracks. Therefore, the 
engine rear mount strut has been redesigned and is pressed fit 
assembled instead of welded which improves the endurance of the strut 
to prevent failure due to cracking and/or fracture.

Explanation of Relevant Service Information

    Bombardier has issued Service Bulletin 8-71-24, dated August 21, 
2001, which describes procedures for replacing the existing rear mount 
struts in a nacelle with new, improved struts. TCCA previously issued 
Canadian airworthiness directive CF-2001-20, dated May 16, 2001, to 
ensure the continued airworthiness of these airplanes in Canada.

FAA's Conclusions

    These airplane models are manufactured in Canada and are 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, TCCA has kept us informed of the 
situation described above. We have examined the findings of TCCA, 
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 supersede AD 94-04-09 to 
require new repetitive inspections of the strut assemblies for cracking 
of the struts replaced per the existing AD, and replacement of any 
cracked strut with a new, machined strut. This proposed AD also would 
change the applicability of the existing AD by adding certain airplanes 
and removing certain other airplanes, and would include an optional 
terminating action for the repetitive inspections.
    Consistent with the findings of TCCA, this proposed AD would allow 
repetitive inspections to continue in lieu of the terminating action. 
In making this determination we considered that long-term continued 
operational safety in this case will be adequately ensured by 
repetitive inspections to find cracking before it represents a hazard 
to the airplane.

Changes to the Applicability of the Existing AD

    This proposed AD would expand the applicability in the existing AD 
to include Model DHC-8-102, -103, -106, -201, -202, -301, -311, and -
315 airplanes; serial numbers 003 through 509 inclusive. Model DHC-8-
102 and -103 series airplanes, serial numbers 003 through 310 
inclusive; and Model DHC-8-301, -311, and -314 series airplanes, serial 
numbers 100 through 311 inclusive, were identified in the existing AD.
    Additionally, this proposed AD would remove Model DHC-8-314 
airplanes, which were added to the applicability of the existing AD but 
are not U.S. type-certificated.

Cost Impact

    There are approximately 192 airplanes of U.S. registry that would 
be affected by this proposed AD.
    The actions that are currently required by AD 94-04-09 take 
approximately 16 work hours per airplane to accomplish, at an average 
labor rate of $65 per work hour. Required parts are provided by the 
manufacturer at no cost to the operators. Based on these figures, the 
cost impact of the currently required actions is estimated to be $1,040 
per airplane.
    The new detailed inspection that is proposed in this AD action 
would take approximately 1 work hour per airplane to accomplish, at an 
average labor rate of $65 per work hour. Based on these figures, the 
cost impact of the proposed inspection on U.S. operators is estimated 
to be $12,480, or $65 per airplane, per inspection cycle.
    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. The cost impact figures 
discussed in AD rulemaking actions represent only the time necessary to 
perform the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.
    The optional terminating action, if done, would take approximately 
16 work hours per strut to accomplish, at an average labor rate of $65 
per work hour. Required parts would cost approximately $800 per strut. 
Based on these figures, the cost impact of the optional terminating 
action is estimated to be $1,840 per strut, per airplane.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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 removing amendment 39-8829 (59 FR 
8393, February 22, 1994), and by adding a new airworthiness directive 
(AD), to read as follows:

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket 2001-NM-266-
AD. Supersedes AD 94-04-09, amendment 39-8829.

    Applicability: Model DHC-8-102, -103, -106, -201, -202, -301, -
311, and -315

[[Page 58285]]

airplanes; serial numbers 003 through 509 inclusive; certificated in 
any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the engine rear mount struts on the left 
and right engine nacelles, which could result in reduced structural 
integrity of the nacelle and engine support structure, accomplish 
the following:

Repetitive Inspections

    (a) Within 1,000 flight hours since installation of any new or 
reworked rear mount strut per the replacement required by paragraph 
(b) of AD 94-04-09, amendment 39-8829, or within 250 flight hours 
after the effective date of this AD, whichever is later; do a 
detailed inspection for cracking of each rear mount strut in the 
left and right engine nacelles.

    Note 1: Bombardier Service Bulletin 8-71-24, dated August 21, 
2001, does not contain inspection procedures for the detailed 
inspection required by paragraph (a) of this AD; however, the 
definition of a detailed inspection is specified in Note 2 of this 
AD.


    Note 2: For the purposes of this AD, a detailed inspection is 
defined as: ``An intensive visual examination of a specific 
structural area, system, installation, or assembly to detect damage, 
failure, or irregularity. Available lighting is normally 
supplemented with a direct source of good lighting at intensity 
deemed appropriate by the inspector. Inspection aids such as mirror, 
magnifying lenses, etc., may be used. Surface cleaning and elaborate 
access procedures may be required.''

    (1) If no crack is found, repeat the inspection at intervals not 
to exceed 250 flight hours, until accomplishment of paragraph (b) of 
this AD.
    (2) If any crack is found, before further flight, replace the 
strut with a new, improved strut per Bombardier Service Bulletin 8-
71-24, dated August 21, 2001. Repeat the inspection thereafter at 
intervals not to exceed 500 flight hours, for that nacelle only.

Optional Terminating Action

    (b) Replacement of both rear mount struts in a nacelle with new, 
improved struts, by doing all the actions specified in the Job Set-
up, Procedure, and Close-out sections of the Accomplishment 
Instructions of Bombardier Service Bulletin 8-71-24, dated August 
21, 2001, ends the repetitive inspections required by this AD for 
that nacelle only. Replacement of both rear mount struts on both the 
left and right engine nacelles ends the repetitive inspections 
required by this AD.

Parts Installation

    (c) As of the effective date of this AD, no person shall install 
an engine rear mount strut, P/N 87110016-001, -003, -005, -007, -
009, or -011, on any airplane.

Alternative Methods of Compliance

    (d) In accordance with 14 CFR 39.19, the Manager, New York 
Aircraft Certification Office, FAA, is authorized to approve 
alternative methods of compliance for this AD.

    Note 3: The subject of this AD is addressed in Canadian 
airworthiness directive CF-2001-20, dated May 16, 2001.


    Issued in Renton, Washington, on October 3, 2003.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-25590 Filed 10-8-03; 8:45 am]
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