Document ID: FAA-2008-0356-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes
Posted Date: 2008-03-25T04:00Z

[Federal Register: March 25, 2008 (Volume 73, Number 58)]
[Proposed Rules]               
[Page 15682-15685]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr25mr08-14]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0356; Directorate Identifier 2008-NM-042-AD]
RIN 2120-AA64

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

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

[[Page 15683]]

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that applies to certain Bombardier Model DHC-8-400 
series airplanes. The existing AD currently 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, the existing AD requires 
doing repetitive visual inspections for cracking of the barrel nuts and 
cradles and replacing all hardware for all cracked barrel nuts. The 
existing 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. The existing AD also 
provides an optional replacement for all affected barrel nuts. This 
proposed AD would require replacement of all affected barrel nuts. This 
proposed AD results from reports of cracking in the barrel nuts at the 
four primary front spar wing-to-fuselage attachment joints. We are 
proposing 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: We must receive comments on this proposed AD by April 24, 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 proposed 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:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2008-0356; 
Directorate Identifier 2008-NM-042-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed 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 proposed AD.

Discussion

    On February 7, 2008, we issued AD 2008-04-02, amendment 39-15374 
(73 FR 8187, February 13, 2008), for certain Bombardier Model DHC-8-400 
series airplanes. That 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, that AD requires doing repetitive visual 
inspections for cracking of the barrel nuts and cradles and replacing 
all hardware for all cracked barrel nuts. That 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. That AD also provides an optional replacement for all 
affected barrel nuts. That AD resulted from reports of cracking in the 
barrel nuts at the four primary front spar wing-to-fuselage attachment 
joints. We issued that 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.

Actions Since Existing AD Was Issued

    The preamble to AD 2008-04-02 explains that we consider the 
requirements ``interim action'' and were considering further rulemaking 
to require the replacement of all hardware for all barrel nuts 
identified with a marking of LH7940T SPS 01. We now have determined 
that further rulemaking is indeed necessary, and this proposed AD 
follows from that determination.

FAA's Determination and Requirements of the Proposed 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, Transport Canada Civil Aviation 
(TCCA) has kept the FAA informed of the situation described above. We 
have examined the TCCA's findings, evaluated all pertinent information, 
and determined that AD action is necessary for airplanes of this type 
design that are certificated for operation in the United States.
    This proposed AD would supersede AD 2008-04-02 and would retain the 
requirements of the existing AD. This proposed AD would also require 
replacement of all affected barrel nuts.

Costs of Compliance

    This proposed AD would affect about 48 airplanes of U.S. registry.
    The actions that are required by AD 2008-04-02 and retained in this 
proposed AD take about 3 work hours per airplane, at an average labor 
rate of $80 per work hour. Based on these figures, the estimated cost 
of the currently required actions is $11,520, or $240 per airplane, per 
inspection cycle.
    Replacement of the hardware of a barrel nut, if required, will take 
about 12 work hours per airplane, at an average labor rate of $80 per 
work hour. Required parts will cost about $800 per airplane. Based on 
these figures, we estimate the cost of a replacement to be $1,760 per 
barrel nut.

[[Page 15684]]

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 
removing amendment 39-15374 (73 FR 8187, February 13, 2008) and adding 
the following new airworthiness directive (AD):

Bombardier, Inc. (Formerly de Havilland, Inc.): Docket No. FAA-2008-
0356; Directorate Identifier 2008-NM-042-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by April 24, 
2008.

Affected ADs

    (b) This AD supersedes AD 2008-04-02.

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.

Restatement of Requirements of AD 2008-04-02

Inspections and Corrective Actions

    (f) Within 50 flight hours after February 13, 2008 (the 
effective date of AD 2008-04-02), 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 pre-load 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

[[Page 15685]]

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.
    (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.

Actions Accomplished According to Previous Issue of Alert Service 
Bulletin

    (h) Actions accomplished before February 13, 2008, 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

    (i) For airplanes on which the actions specified in Bombardier 
Alert Service Bulletin A84-57-18, dated January 16, 2008, were 
accomplished before February 13, 2008 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

    (j) As of February 13, 2008, no person may install a barrel nut, 
part number DSC228-16, identified with a marking of LH7940T SPS 01, 
on any airplane.

New Requirement of This AD

Replacement of All Affected Barrel Nuts

    (k) For airplanes on which barrel nuts are inspected in 
accordance with paragraph (g)(1)(iii), (g)(2)(iii), (g)(3)(iii), 
(g)(4), or (g)(5) of this AD: Within 3,000 flight hours after the 
effective date of this AD, replace all hardware for all remaining 
barrel nuts, part number DSC228-16, identified with a marking of 
LH7940T SPS 01. Do the replacement in accordance with the 
Accomplishment Instructions of Bombardier Alert Service Bulletin 
A84-57-19, Revision A, dated February 6, 2008. Replacement of all 
hardware for all affected barrel nuts constitutes terminating action 
for this AD.

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), 
(1)(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.

    Issued in Renton, Washington, on March 17, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.

 [FR Doc. E8-6054 Filed 3-24-08; 8:45 am]

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