[Federal Register Volume 72, Number 60 (Thursday, March 29, 2007)]
[Proposed Rules]
[Pages 14721-14724]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-5668]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-27713; Directorate Identifier 2006-NM-240-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-100, DHC-8-200, 
and DHC-8-300 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Bombardier Model DHC-8-100, DHC-8-200, and DHC-8-300 series 
airplanes. This proposed AD would

[[Page 14722]]

require, for certain airplanes, modification of the upper bearing of 
the main landing gear (MLG) shock strut. This proposed AD would also 
require, for certain airplanes, revising the DHC-8 Maintenance Program 
Manual to include the MLG shock strut servicing task. This proposed AD 
results from reports of over-extension of the MLG shock strut piston, 
which allows the torque links to go over-center and rest on the piston. 
We are proposing this AD to prevent loss in shock absorption during 
touchdown and failure of the shock strut housing, which could result in 
a subsequent loss of directional control.

DATES: We must receive comments on this proposed AD by April 30, 2007.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, 
Washington, DC 20590.
    <bullet> Fax: (202) 493-2251.
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Bombardier, Inc., Bombardier Regional Aircraft Division, 
123 Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada, for service 
information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT: Mazdak Hobbi, Aerospace Engineer, 
Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft 
Certification Office, 1600 Stewart Avenue, suite 410, Westbury, New 
York 11590; telephone (516) 228-7330; fax (516) 794-5531.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``FAA-2007-
27713; Directorate Identifier 2006-NM-240-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of the proposed AD. We will 
consider all comments received by the closing date and may amend the 
proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may visit http://dms.dot.gov.

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the Docket Management System 
receives them.

Discussion

    Transport Canada Civil Aviation (TCCA), which is the airworthiness 
authority for Canada, notified us that an unsafe condition may exist on 
certain Bombardier Model DHC-8-100, DHC-8-200, and DHC-8-300 series 
airplanes. TCCA advises that there have been six cases reported in 
which the main landing gear (MLG) shock strut piston over-extended, 
allowing the torque links to go over-center and rest on the piston. 
Investigation has revealed that over-extension of the shock strut 
resulted from damage to the upper bearing and seal carrier, caused by a 
loss of internal damping.
    Over-extension of the MLG shock strut piston, if not corrected, 
could result in loss in shock absorption during touchdown and failure 
of the shock strut housing, which could result in a subsequent loss of 
directional control.

Relevant Service Information

    Bombardier has issued Service Bulletin 8-32-144, Revision `A,' 
dated April 29, 2002, including Messier-Dowty Service Bulletin M-DT 
SBDHC8-32-82, Revision 1, dated July 5, 2001 (for Model DHC-8-311, -
314, and -315 airplanes). The service bulletin describes procedures for 
modifying the upper bearing in each MLG. The modification includes an 
inspection of the two halves of the upper bearing for wear and damage, 
the removal of the needle roller from the upper bearing, an inspection 
of the cylinder bore for damage and wear, and corrective action if 
necessary. The corrective action includes replacing the upper bearing 
with a new bearing and contacting the parts manufacturer if damage or 
wear that exceeds the maximum diameter is found on the cylinder bore.
    Bombardier has issued the following de Havilland Dash 8 maintenance 
task cards to the applicable Bombardier DHC-8 Maintenance Program 
Manual (Program Support Manuals 1-8-7, 1-82-7, and 1-83-7). These tasks 
describe procedures for servicing the MLG shock struts:
    <bullet> Dash 8 Series 100 Maintenance Task Card 3210/15, dated 
June 22, 2005;
    <bullet> Dash 8 Series 200 Maintenance Task Card 3210/15, dated 
June 22, 2005; and
    <bullet> Dash 8 Series 300 Maintenance Task Card 3210/15, dated 
November 29, 2005.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition. TCCA mandated the 
service information and issued Canadian airworthiness directive CF-
2006-14, effective July 21, 2006, to ensure the continued airworthiness 
of these airplanes in Canada.

FAA's Determination and Requirements of the Proposed AD

    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 the FAA informed of 
the situation described above. We have examined TCCA's findings, 
evaluated all pertinent information, and determined that we need to 
issue an AD for airplanes of this type design that are certificated for 
operation in the United States.
    Therefore, we are proposing this AD, which would require, for 
certain airplanes, accomplishing the actions specified in the service 
bulletin described previously, and, for certain airplanes, revising the 
applicable DCH-8 Maintenance Program Manual to include the MLG shock 
strut servicing Task 3210/15, except as discussed

[[Page 14723]]

under ``Difference Between the Proposed AD and the Service Bulletin.''

Difference Between the Proposed AD and the Service Bulletin

    The service bulletin specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions using a method that we or TCCA 
(or its delegated agent) approve. In light of the type of repair that 
would be required to address the unsafe condition, and consistent with 
existing bilateral airworthiness agreements, we have determined that, 
for this proposed AD, a repair we or TCCA approve would be acceptable 
for compliance with this proposed AD.

Costs of Compliance

    The following table provides the estimated costs for U.S. operators 
to comply with this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Average
                Action                   Work hours   labor rate     Parts       Cost per     Number of U.S.-registered              Fleet cost
                                                       per hour                  airplane             airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Modification..........................            4          $80         $274         $594  Up to 135....................  Up to $80,190.
Manual Revision.......................            1           80            0           80  135..........................  $10,800.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket No. FAA-2007-
27713; Directorate Identifier 2006-NM-240-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by April 30, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Bombardier Model DHC-8-101, -102, -103, -
106, -201, -202, -301, -311, -314, and -315 airplanes, certificated 
in any category; serial numbers 003 through 618 inclusive.

Unsafe Condition

    (d) This AD results from reports of over-extension of the main 
landing gear (MLG) shock strut piston, which allows the torque links 
to go over-center and rest on the piston. We are issuing this AD to 
prevent loss in shock absorption during touchdown and failure of the 
shock strut housing, which could result in a subsequent loss of 
directional control.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Modification of the Upper Bearing

    (f) For Model DHC-8-311, -314, and -315 airplanes, serial 
numbers 202 through 516 inclusive, with MLG shock struts having any 
serial number DCL3501/90 through DCL3768/97 inclusive installed: 
Within 3,000 flight hours after the effective date of this AD, 
modify the upper bearing in each MLG (including doing inspections of 
the upper bearing and cylinder bore for wear and damage, and doing 
all applicable corrective actions) in accordance with the 
Accomplishment Instructions of Bombardier Service Bulletin 8-32-144, 
Revision `A,' dated April 29, 2002, including Messier-Dowty Service 
Bulletin M-DT SBDHC8-32-82, Revision 1, dated July 5, 2001, except 
if wear exceeds the maximum diameter specified in the service 
bulletin for the cylinder bore or if damage is found on the cylinder 
bore, before further flight, repair using a method approved by 
either the Manager, International Branch, ANM-116, Transport 
Airplane Directorate, FAA; or Transport Canada Civil Aviation (TCCA) 
(or its delegated agent). Do all applicable corrective actions 
before further flight.

Revision of the Maintenance Program Manual

    (g) For Model DHC-8-101, -102, -103, -106, -201, -202, -301, -
311, -314, and -315 airplanes, serial numbers 003 through 614 
inclusive: Within 30 days after the effective date of this AD, 
revise Part 1 of the applicable DHC-8 Maintenance Program Manual by 
incorporating the applicable MLG shock strut servicing Task 3210/15 
specified in Table 1 of this AD.

    Note 1: This may be done by inserting copies of the applicable 
task into the applicable maintenance program manual. When these 
tasks have been included in the general revisions of the applicable

[[Page 14724]]

maintenance program manual, the general revisions may be inserted in 
the applicable maintenance program manual and the copy of the task 
may be removed from the maintenance program manual.


                                                 Table 1.--Tasks
----------------------------------------------------------------------------------------------------------------
                                                                      To the  program
                 Task--                            Dated--            support manual          For model--
                                                                          (PSM)--
----------------------------------------------------------------------------------------------------------------
Dash 8 Series 100 Maintenance Task Card  June 22, 2005.............             1-8-7  DHC-8-100 Series
 3210/15.                                                                               Airplanes.
Dash 8 Series 200 Maintenance Task Card  June 22, 2005.............            1-82-7  DHC-8-200 Series
 3210/15.                                                                               Airplanes.
Dash 8 Series 300 Maintenance Task Card  November 29, 2005.........            1-83-7  DHC-8-300 Series
 3210/15.                                                                               Airplanes.
----------------------------------------------------------------------------------------------------------------

Parts Installation

    (h) After the effective date of this AD, no person may install a 
part identified in paragraphs (h)(1) and (h)(2) of this AD, as a 
replacement during the repair or overhaul of any shock strut 
assembly, on any airplane.
    (1) Upper bearing, part number 10130-3 or 10130-551.
    (2) Damper ring, part number 10129-3 or 10129-551.
    (i) After the effective date of this AD, only the parts 
identified in paragraphs (i)(1) and (i)(2) of this AD may be 
installed on any airplane as replacement upper bearings and damper 
rings during the repair or overhaul of any shock strut assembly, 
except as provided by paragraph (j) of this AD.
    (1) Upper bearing, part number 10130-5.
    (2) Damper ring, part number 10129-5 or 10129-533.
    (j) After the effective date of this AD, only MLGs with a 
reworked, oversize cylinder bore (part number identified in the 
applicable component maintenance manual (CMM)) that have parts 
identified in paragraphs (j)(1), (j)(2), and (j)(3) of this AD used 
in accordance with the applicable CMM may be installed on any 
airplane.
    (1) Upper bearing, part number CRS85-167-11.
    (2) Damper ring, part number CRS85-167-31 or CRS85-167-33.
    (3) Seal carrier, part number CRS85-167-21.

Credit for Actions Done Using Previous Service Information

    (k) Modifications accomplished before the effective date of this 
AD in accordance with Bombardier Service Bulletin 8-32-144, dated 
August 10, 1998, including Messier-Dowty Service Bulletin M-DT 
SBDCH8-32-82, dated March 9, 1998, are considered acceptable for 
compliance with the corresponding actions specified in this AD.

Alternative Methods of Compliance (AMOCs)

    (l)(1) The Manager, New York Aircraft Certification Office, FAA, 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Related Information

    (m) Canadian airworthiness directive CF-2006-14, effective July 
21, 2006, also addresses the subject of this AD.

    Issued in Renton, Washington, on March 20, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-5668 Filed 3-28-07; 8:45 am]
BILLING CODE 4910-13-P