[Federal Register Volume 71, Number 213 (Friday, November 3, 2006)]
[Proposed Rules]
[Pages 64651-64653]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-18573]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-26241; Directorate Identifier 2006-NM-155-AD]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model DHC-8-400 Series 
Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Bombardier Model DHC-8-400 series airplanes. This proposed 
AD would require inspecting to determine the manufacturer's date of 
certain V-band clamps on the engine exhaust shroud assembly, and doing 
related investigative/corrective actions if necessary. This proposed AD 
results from a report of a discrepancy found during a maintenance 
inspection on a V-band clamp located on the engine exhaust duct shroud. 
The clamp ends were touching (although the correct fastener torque had 
been applied), resulting in reduced clamp force on the flanges. We are 
proposing this AD to prevent vibration in the duct shroud and fretting 
of the V-band clamp and flanges, which could result in cracking of the 
flanges and consequent release of hot exhaust gases from the engine 
tailpipe and damage to adjacent structure. This situation could trigger 
the fire warning system and result in an in-flight emergency, such as 
the flightcrew shutting down the engine and activating the fire 
suppression system.

DATES: We must receive comments on this proposed AD by December 4, 
2006.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590.
     Fax: (202) 493-2251.
     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: Richard Fiesel, 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) 228-7304; 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-2006-
26241; Directorate Identifier 2006-NM-155-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.

[[Page 64652]]

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-8-400 series airplanes. TCCA advises of a 
report of a discrepancy found during a maintenance inspection on a V-
band clamp located on the engine exhaust duct shroud. The clamp ends 
were touching (although the correct fastener torque had been applied), 
resulting in reduced clamp force on the flanges. Investigation revealed 
that a batch of V-band clamps were not manufactured to the drawing 
specifications. These clamps may cause vibration and fretting of the V-
band clamp flanges to occur, leading to flange cracking and local area 
overheating. These conditions, if not corrected, could result in 
cracking of the flanges and consequent release of hot exhaust gases 
from the engine tailpipe and damage to adjacent structure. This 
situation could trigger the fire warning system and result in an in-
flight emergency, such as the flightcrew shutting down the engine and 
activating the fire suppression system.

Relevant Service Information

    Bombardier has issued Service Bulletin 84-78-01, Revision `A,' 
dated September 15, 2005. The service bulletin describes procedures for 
inspecting to determine the manufacturer's date of certain V-band 
clamps on the engine exhaust shroud assembly, and doing related 
investigative and corrective actions if necessary. The related 
investigative action is measuring the gap between the clamp loops at 
the T-bolt and trunnion. The related corrective actions are as follows:
     If both clamp loops touch when the clamp is tightened to 
the specified torque value: Replace the V-band clamp with a serviceable 
clamp.
     If the gap between the clamp loops is less than 0.050 inch 
when the clamp is tightened to the specified torque value: Replace the 
V-band clamp on or before the next C-check.
    The corrective actions also include inspecting the flange of the 
shroud assemblies for any of the following discrepancies:
     Indication(s) of exhaust gas leakage.
     Damage to surrounding structure or adjacent assemblies as 
a result of gas leakage.
     Indication(s) of chafing, fretting, or cracking at the 
flanges of the related shrouds.
    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-
2006-06, dated April 4, 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 
accomplishing the actions specified in the service information 
described previously, except as discussed under ``Differences Between 
the Proposed AD and Service Information.''

Differences Between the Proposed AD and Service Information

    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.
    The service bulletin specifies replacing the V-band clamp ``on or 
before the next C-check'' as part of the corrective actions. This 
proposed AD would require doing all corrective actions before further 
flight.

Costs of Compliance

    This proposed AD would affect about 21 airplanes of U.S. registry. 
The proposed actions would take about 3 work hours per airplane, at an 
average labor rate of $80 per work hour. Required parts cost would be 
minimal. Based on these figures, the estimated cost of the proposed AD 
for U.S. operators is $5,040, or $240 per airplane.

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

[[Page 64653]]

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-2006-
26241; Directorate Identifier 2006-NM-155-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by December 
4, 2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Bombardier Model DHC-8-400 series 
airplanes, certificated in any category; as identified in Bombardier 
Service Bulletin 84-78-01, Revision `A,' dated September 15, 2005.

Unsafe Condition

    (d) This AD results from a report of a discrepancy found during 
a maintenance inspection on a V-band clamp located on the engine 
exhaust duct shroud. The clamp ends were touching (although the 
correct fastener torque had been applied), resulting in reduced 
clamp force on the flanges. We are issuing this AD to prevent 
vibration in the duct shroud and fretting of the V-band clamp and 
flanges, which could result in cracking of the flanges and 
consequent release of hot exhaust gases from the engine tailpipe and 
damage to adjacent structure. This situation could trigger the fire 
warning system and result in an in-flight emergency, such as the 
flightcrew shutting down the engine and activating the fire 
suppression system.

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.

Inspection/Investigative and Corrective Actions

    (f) Within 5,000 flight hours after the effective date of this 
AD: Inspect to determine the part number (P/N) of the V-band clamps 
on the engine exhaust duct shroud in accordance with the 
Accomplishment Instructions of Bombardier Service Bulletin 84-78-01, 
Revision `A,' dated September 15, 2005. For any V-band clamp having 
P/N VC1642A-2030-A or VC1642A-1875-A, before further flight, 
determine the manufacturer's date and do all applicable related 
investigative and corrective actions (including inspecting the 
flange of the shroud assemblies for discrepancies), by accomplishing 
all the actions specified in the Accomplishment Instructions of the 
service bulletin; except as provided by paragraph (g) of this AD. Do 
all applicable related investigative and corrective actions before 
further flight.
    (g) If, during the accomplishment of the corrective actions 
required by paragraph (f) of this AD, the service bulletin specifies 
contacting the manufacturer for repair instructions, before further 
flight, repair in accordance with a method approved by either the 
Manager, New York Aircraft Certification Office (ACO), FAA; or 
Transport Canada Civil Aviation (TCCA) (or its delegated agent).

Actions Accomplished According to Previous Issue of Service Bulletin

    (h) Actions accomplished before the effective date of this AD 
according to Bombardier Service Bulletin 84-78-01, dated March 22, 
2005, are considered acceptable for compliance with the 
corresponding actions specified in paragraph (f) of this AD.

Parts Installation

    (i) As of the effective date of this AD, no person may install a 
V-band clamp, P/N VC1642A-2030-A or VC1642A-1875-A, with a 
manufacturer batch stamp dated before ``08-02,'' on any airplane.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, New York ACO, 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

    (k) Canadian airworthiness directive CF-2006-06, dated April 4, 
2006, also addresses the subject of this AD.

    Issued in Renton, Washington, on October 26, 2006.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-18573 Filed 11-2-06; 8:45 am]
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