

[Federal Register: February 13, 2008 (Volume 73, Number 30)]
[Rules and Regulations]               
[Page 8187-8190]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr13fe08-2]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0167; Directorate Identifier 2008-NM-029-AD; 
Amendment 39-15374; AD 2008-04-02]
RIN 2120-AA64

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

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

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Bombardier Model DHC-8-400 series airplanes. This AD requires 
inspecting all barrel nuts to determine if the barrel nuts have a 
certain marking, inspecting affected bolts to determine if the bolts 
are pre-loaded correctly, and replacing all hardware if the pre-load is 
incorrect. For airplanes on which the pre-load is correct, this AD 
requires doing repetitive visual inspections for cracking of the barrel 
nuts and cradles and replacing all hardware for all cracked barrel 
nuts. This AD also requires replacement of all hardware for certain 
affected barrel nuts that do not have cracking, which would end the 
repetitive inspections for those airplanes. This AD also provides an 
optional replacement for all affected barrel nuts. This AD results from 
reports of cracking in the barrel nuts at the four primary front spar 
wing-to-fuselage attachment joints. We are issuing this AD to detect 
and correct cracking of the barrel nuts at the wing front spar wing-to-
fuselage joints, which could result in reduced structural integrity of 
the wing-to-fuselage attachments and consequent detachment of the wing.

DATES: This AD becomes effective February 13, 2008.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of February 13, 
2008.
    We must receive comments on this AD by March 14, 2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov.
 Follow the instructions for submitting comments.

     Fax: (202) 493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building, Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building, Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Bombardier, 
Inc., Bombardier Regional Aircraft Division, 123 Garratt Boulevard, 
Downsview, Ontario M3K 1Y5, Canada.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov
; or in person at the Docket Management Facility 

between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this AD, the regulatory evaluation, 
any comments received, and other information. The street address for 
the Docket Office (telephone 800-647-5527) is in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Pong Lee, 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) 228-7324; fax (516) 794-5531.

SUPPLEMENTARY INFORMATION: 

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 that 
during scheduled maintenance, an operator found cracks in the barrel 
nut at one of the four primary front spar wing-to-fuselage attachment 
joints. Investigation

[[Page 8188]]

determined that the cracks were due to hydrogen embrittlement and that 
the problem is likely restricted to a batch of 166 barrel nuts from one 
supplier. In addition, another operator has reported finding cracked 
barrel nuts at three of the four wing front spar wing-to-fuselage 
joints on one aircraft. All three barrel nuts were from the suspect 
batch. Cracking of the barrel nuts, if not detected and corrected, 
could result in reduced structural integrity of the wing-to-fuselage 
attachments and consequent detachment of the wing.

Relevant Service Information

    Bombardier has issued Alert Service Bulletin A84-57-19, Revision A, 
dated February 6, 2008. The service bulletin describes the following 
procedures:
     Determining whether the inboard and outboard bolts are 
correctly pre-loaded.
     Replacing all hardware at locations where the pre-load is 
incorrect.
     Doing a visual inspection of the barrel nut and cradle for 
cracking.
     Replacing cracked barrel nuts with all new hardware.
     Doing an inspection for certain markings of the barrel 
nuts.
     Replacing barrel nuts having the affected markings.

TCCA mandated the service bulletin and issued Canadian emergency 
airworthiness directive CF-2008-11, dated February 5, 2008, to ensure 
the continued airworthiness of these airplanes in Canada.

FAA's Determination and Requirements of This AD

    These airplanes 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 products of this type design that are certificated for 
operation in the United States.
    Therefore, we are issuing this AD to detect and correct cracking of 
the barrel nuts at the wing front spar wing-to-fuselage joints, which 
could result in reduced structural integrity of the wing-to-fuselage 
attachments and consequent detachment of the wing.
    This AD requires the following actions:
     Inspecting all barrel nuts to determine if the barrel nuts 
have a marking of LH7940T SPS 01 (all barrel nuts with this marking 
will also have a yellow dot identifier).
     Inspecting (repetitively) affected bolts to determine if 
the bolts are pre-loaded correctly.
     Replacing all hardware if the pre-load is incorrect.
     Doing repetitive visual inspections for cracking of the 
barrel nuts and cradles for airplanes on which the pre-load is correct.
     Replacing all hardware for all cracked barrel nuts.
     Replacing all hardware for certain affected barrel nuts 
that do not have cracking, which would end the repetitive inspections 
for those airplanes. This AD also provides an optional replacement for 
all affected barrel nuts.

Differences Between the AD and Canadian Emergency Airworthiness 
Directive

    The Canadian emergency airworthiness directive recommends 
accomplishing the inspection of the barrel nuts within 100 flight 
hours. We have determined, however, that the inspection must be done 
within 50 flight hours to adequately address the unsafe condition. In 
developing an appropriate compliance time for all airplanes that are 
affected by this AD, we considered not only the manufacturer's 
recommendation, but the degree of urgency associated with addressing 
the subject unsafe condition, the average utilization of the affected 
fleet, and the time necessary to perform the required inspections. We 
have coordinated this difference with TCCA.
    We consider this AD interim action. We are currently considering 
requiring the replacement of all hardware for all barrel nuts 
identified with a marking of LH7940T SPS 01, as required by the 
Canadian emergency airworthiness directive. However, the planned 
compliance time for the replacement would allow enough time to provide 
notice and opportunity for prior public comment on the merits of the 
modification. In order to ensure continued operational safety in the 
interim, this AD requires repetitive inspections for cracking of the 
suspect barrel nuts every 100 flight hours until the replacement is 
done.

FAA's Justification and Determination of the Effective Date

    Cracking of the barrel nuts at the wing front spar wing-to-fuselage 
joints could result in reduced structural integrity of the wing-to-
fuselage attachments and consequent detachment of the wing. Because of 
our requirement to promote safe flight of civil aircraft and thus, the 
critical need to assure the structural integrity of the front spar 
wing-to-fuselage attachment joints and the short compliance time 
involved with this action, this AD must be issued immediately.
    Because an unsafe condition exists that requires the immediate 
adoption of this AD, we find that notice and opportunity for prior 
public comment hereon are impracticable and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    This AD is a final rule that involves requirements affecting flight 
safety, and we did not provide you with notice and an opportunity to 
provide your comments before it becomes effective. However, we invite 
you to send any written data, views, or arguments about this AD. Send 
your comments to an address listed under the ADDRESSES section. Include 
``Docket No. FAA-2008-0167; Directorate Identifier 2008-NM-029-AD'' at 
the beginning of your comments. We specifically invite comments on the 
overall regulatory, economic, environmental, and energy aspects of this 
AD. We will consider all comments received by the closing date and may 
amend this AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov
, including any personal information you provide. We 

will also post a report summarizing each substantive verbal contact we 
receive about this AD.

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.

[[Page 8189]]

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will 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 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 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

2008-04-02 Bombardier, Inc. (Formerly de Havilland, Inc.): Amendment 
39-15374. Docket No. FAA-2008-0167; Directorate Identifier 2008-NM-
029-AD.

Effective Date

    (a) This AD becomes effective February 13, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Bombardier Model DHC-8-400, DHC-8-401, 
and DHC-8-402 airplanes, certificated in any category; serial 
numbers 4001 and 4003 through 4176 inclusive.

Unsafe Condition

    (d) This AD results from reports of cracking in the barrel nuts 
at the four primary front spar wing-to-fuselage attachment joints. 
We are issuing this AD to detect and correct cracking of the barrel 
nuts at the wing front spar wing-to-fuselage joints, which could 
result in reduced structural integrity of the wing-to-fuselage 
attachments and consequent detachment of the wing.

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.

Inspections and Corrective Actions

    (f) Within 50 flight hours after the effective date of this AD, 
inspect all barrel nuts, part number DSC228-16, to determine if the 
barrel nuts are identified with a marking of LH7940T SPS 01. Inspect 
in accordance with the Accomplishment Instructions of Bombardier 
Alert Service Bulletin A84-57-19, Revision A, dated February 6, 
2008.
    (1) If no barrel nuts are identified with a marking of LH7940T 
SPS 01, no further actions are required by this paragraph.
    (2) If any barrel nut is found that is identified with a marking 
of LH7940T SPS 01, before further flight, inspect the inboard and 
outboard bolts to determine if the bolts are pre-loaded correctly. 
Inspect in accordance with the Accomplishment Instructions of 
Bombardier Alert Service Bulletin A84-57-19, Revision A, dated 
February 6, 2008.
    (i) If the pre-load is incorrect (i.e., the ring can be 
rotated), before further flight, replace all hardware at that 
location in accordance with the Accomplishment Instructions of the 
alert service bulletin.
    (ii) If the preload is correct, before further flight, do a 
visual inspection for cracking of the barrel nuts and cradles in 
accordance with the Accomplishment Instructions of the alert service 
bulletin.
    (A) If no cracking of the barrel nut and cradle is found, do the 
applicable action required by paragraph (g) of this AD.
    (B) If no cracking of the barrel nut is found and only cracking 
of the cradle is found, no action is required by this paragraph 
provided that the applicable corrective action specified in 
paragraph (g) of this AD is done.
    (C) If any cracking of the barrel nut is found, before next 
flight, replace all hardware only at that location in accordance 
with the Accomplishment Instructions of the alert service bulletin.
    (g) For any barrel nuts on which no cracking of the barrel nut 
was found during the inspection required by paragraph (f)(2)(ii) of 
this AD, do the applicable corrective action specified in paragraph 
(g)(1), (g)(2), (g)(3), (g)(4), or (g)(5) of this AD at the 
compliance time specified in the applicable paragraph.
    (1) If four barrel nuts having no cracking are found, do the 
actions specified in paragraphs (g)(1)(i), (g)(1)(ii), and 
(g)(1)(iii) of this AD.
    (i) Within 50 flight hours after doing the inspection required 
by paragraph (f)(2)(ii) of this AD, repeat the inspection specified 
in paragraph (f)(2) of this AD. Thereafter, repeat the inspection at 
intervals not to exceed 50 flight hours until the replacement 
specified in paragraph (g)(1)(ii) of this AD is done.
    (ii) Within 100 flight hours after doing the inspection required 
by paragraph (f)(2)(ii) of this AD, replace all hardware at the 
left-hand outboard location and the right-hand outboard location in 
accordance with the Accomplishment Instructions of Bombardier Alert 
Service Bulletin A84-57-19, Revision A, dated February 6, 2008. 
Replacing the barrel nuts on the outboard locations terminates the 
requirement to do the repetitive inspections specified in paragraph 
(g)(1)(i) of this AD.
    (iii) Within 100 flight hours after doing the replacement 
required by paragraph (g)(1)(ii) of this AD, repeat the inspection 
specified in paragraph (f)(2) of this AD for the remaining barrel 
nuts identified with a marking of LH7940T SPS 01. Thereafter, repeat 
the inspection at intervals not to exceed 100 flight hours until the 
replacement of all hardware at those locations is done. Do the 
inspection and replacement in accordance with the Accomplishment 
Instructions of Bombardier Alert Service Bulletin A84-57-19, 
Revision A, dated February 6, 2008.
    (2) If three barrel nuts having no cracking are found, do the 
actions specified in paragraphs (g)(2)(i), (g)(2)(ii), and 
(g)(2)(iii) of this AD.
    (i) Within 50 flight hours after doing the inspection required 
by paragraph (f)(2)(ii) of this AD, repeat the inspection specified 
in paragraph (f)(2) of this AD. Thereafter, repeat the inspection at 
intervals not to exceed 50 flight hours until the replacement 
specified in paragraph (g)(2)(ii) of this AD is done.
    (ii) Within 100 flight hours after doing the inspection required 
by paragraph (f)(2)(ii) of this AD, replace all hardware for one 
affected barrel nut at the outboard location, on the side with two 
affected barrel nuts, in accordance with the Accomplishment 
Instructions of Bombardier Alert Service Bulletin A84-57-19, 
Revision A, dated February 6, 2008. Replacing the barrel nut on the 
outboard location terminates the requirement to do the repetitive 
inspections specified in paragraph (g)(2)(i) of this AD.
    (iii) Within 100 flight hours after doing the replacement 
required by paragraph (g)(2)(ii) of this AD, repeat the inspection 
specified in paragraph (f)(2) of this AD for the remaining barrel 
nuts identified with a marking of LH7940T SPS 01. Thereafter, repeat 
the inspection at intervals not to exceed 100 flight hours until the 
replacement of all hardware at those locations is done. Do the 
inspection and replacement in accordance with the Accomplishment 
Instructions of Bombardier Alert Service Bulletin A84-57-19, 
Revision A, dated February 6, 2008.
    (3) If two barrel nuts having no cracking are found and both 
nuts are on the same side, do the actions specified in paragraphs 
(g)(3)(i), (g)(3)(ii), and (g)(3)(iii) of this AD.
    (i) Within 100 flight hours after doing the inspection required 
by paragraph (f)(2)(ii) of this AD, repeat the inspection specified 
in paragraph (f)(2) of this AD. Thereafter, repeat the inspection at 
intervals not to exceed 100 flight hours until the replacement 
specified in paragraph (g)(3)(ii) of this AD is done.

[[Page 8190]]

    (ii) Within 500 flight hours after doing the inspection required 
by paragraph (f)(2)(ii) of this AD, replace all hardware for one 
affected barrel nut at the outboard location that has two affected 
barrel nuts in accordance with the Accomplishment Instructions of 
Bombardier Alert Service Bulletin A84-57-19, Revision A, dated 
February 6, 2008. Replacing the barrel nut on the outboard location 
terminates the requirement to do the repetitive inspections 
specified in paragraph (g)(3)(i) of this AD.
    (iii) Within 100 flight hours after doing the replacement 
required by paragraph (g)(3)(ii) of this AD, repeat the inspection 
specified in paragraph (f)(2) of this AD for the remaining barrel 
nut identified with a marking of LH7940T SPS 01. Thereafter, repeat 
the inspection at intervals not to exceed 100 flight hours until the 
replacement of all hardware at that location is done. Do the 
inspection and replacement in accordance with the Accomplishment 
Instructions of Bombardier Alert Service Bulletin A84-57-19, 
Revision A, dated February 6, 2008.
    (4) If two barrel nuts having no cracking are found and are on 
opposite sides, within 100 flight hours after doing the inspection 
required by paragraph (f)(2)(ii) of this AD, repeat the inspection 
specified in paragraph (f)(2) of this AD. Thereafter, repeat the 
inspection at intervals not to exceed 100 flight hours until the 
replacement of all hardware at those locations is done. Do the 
inspection and replacement in accordance with the Accomplishment 
Instructions of Bombardier Alert Service Bulletin A84-57-19, 
Revision A, dated February 6, 2008.
    (5) If one barrel nut having no cracking is found, within 100 
flight hours after doing the inspection required by paragraph 
(f)(2)(ii) of this AD, repeat the inspection specified in paragraph 
(f)(2) of this AD. Thereafter, repeat the inspection at intervals 
not to exceed 100 flight hours until the replacement of all hardware 
at that location is done. Do the inspection and replacement in 
accordance with the Accomplishment Instructions of Bombardier Alert 
Service Bulletin A84-57-19, Revision A, dated February 6, 2008.

Optional Replacement

    (h) Replacement of all hardware for all barrel nuts, part number 
DSC228-16, identified with a marking of LH7940T SPS 01, constitutes 
terminating action for this AD. Replacement must be done in 
accordance with the Accomplishment Instructions of Bombardier Alert 
Service Bulletin A84-57-19, Revision A, dated February 6, 2008.

Actions Accomplished According to Previous Issue of Alert Service 
Bulletin

    (i) Actions accomplished before the effective date of this AD in 
accordance with Bombardier Alert Service Bulletin A84-57-19, dated 
February 1, 2008, are acceptable for compliance with the 
corresponding actions specified in this AD.

Actions Accomplished According to Bombardier Alert Service Bulletin 
A84-57-18

    (j) For airplanes on which the actions specified in Bombardier 
Alert Service Bulletin A84-57-18, dated January 16, 2008, were 
accomplished before the effective date of this AD and on which no 
barrel nuts were found that were identified with a marking of 
LH7940T SPS 01: No further action is required by this AD.

Parts Installation

    (k) As of the effective date of this AD, no person may install a 
barrel nut, part number DSC228-16, identified with a marking of 
LH7940T SPS 01, on any airplane.

Special Flight Permit

    (l) Special flight permits, as described in Section 21.197 and 
Section 21.199 of the Federal Aviation Regulations (14 CFR 21.197 
and 21.199), may be issued to operate the airplane to a location 
where the requirements of this AD can be accomplished but 
concurrence by the Manager, New York Aircraft Certification Office, 
FAA, is required prior to issuance of the special flight permit. 
Before using any approved special flight permits, notify your 
appropriate principal inspector (PI) in the FAA Flight Standards 
District Office (FSDO), or lacking a PI, your local FSDO. Special 
flight permits may be permitted provided that the conditions 
specified in paragraph (l)(1), (l)(2), (l)(3), (l)(4), and (l)(5) of 
this AD are met.
    (1) Both the right-hand side and left-hand side of the airplane 
must have at least one barrel nut that is not within the suspect 
batch (i.e., barrel nut is not identified with a marking of LH7940T 
SPS 01). The barrel nuts that are not within the suspect batch must 
be in good working condition (i.e., no cracking of the barrel nut).
    (2) No passengers and no cargo are onboard.
    (3) Airplane must operate in fair weather conditions with a low 
risk of turbulence.
    (4) Airplane must operate with reduced airspeed. For further 
information, contact Bombardier, Q Series 24 Hour Service Customer 
Response Center, at: Tel: 1-416-375-4000; Fax: 1-416-375-4539; E-
mail: thd.qseries@aero.bombardier.com.
    (5) All of the conditions specified in paragraphs (l)(1), 
(l)(2), (l)(3), and (l)(4) of this AD are on a case-by-case basis. 
Contact your appropriate principal inspector (PI) in the FAA Flight 
Standards District Office (FSDO), or lacking a PI, your local FSDO, 
for assistance.

Alternative Methods of Compliance (AMOCs)

    (m)(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) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

Related Information

    (n) Canadian emergency airworthiness directive CF-2008-11, dated 
February 5, 2008.

Material Incorporated by Reference

    (o) You must use Bombardier Alert Service Bulletin A84-57-19, 
Revision A, dated February 6, 2008, to perform the actions that are 
required by this AD, unless the AD specifies otherwise. The Director 
of the Federal Register approved the incorporation by reference of 
this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
Contact Bombardier, Inc., Bombardier Regional Aircraft Division, 123 
Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada, for a copy of 
this service information. You may review copies at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html
.


    Issued in Renton, Washington, on February 7, 2008.
Kevin Hull,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-2747 Filed 2-12-08; 8:45 am]

BILLING CODE 4910-13-P
