Airworthiness Directives; Boeing Model 737-300, -400, and -500 Series Airplanes

[Federal Register Volume 74, Number 215 (Monday, November 9, 2009)]
[Rules and Regulations]
[Pages 57564-57567]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-26581]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2009-1026; Directorate Identifier 2009-NM-197-AD; 
Amendment 39-16084; AD 2009-23-10]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
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 superseding an existing airworthiness directive 
(AD) that applies to all Boeing Model 737-300, -400, and -500 series 
airplanes. The existing AD currently requires inspecting to determine 
if certain carriage spindles are installed, repetitive inspections for 
corrosion and indications of corrosion on affected carriage spindles, 
and if necessary, related investigative and corrective actions. The 
existing AD also provides optional terminating action. For certain 
airplanes, this new AD would reinstate the requirements of the existing 
AD. This AD results from the exclusion of certain carriage spindles 
from the requirements of the existing AD, and additional reports of 
corrosion found on carriage spindles that are located on the outboard 
trailing edge flaps. We are issuing this AD to detect and correct 
corrosion of the carriage spindle, which could result in fracture. 
Fracture of both the inboard and outboard carriage spindles, in the 
forward ends through the large diameters, on a flap, could adversely 
affect the airplane's continued safe flight and landing.

DATES: This AD becomes effective November 24, 2009.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of November 24, 
2009.
    On August 5, 2008 (73 FR 42259, July 21, 2008), the Director of the 
Federal Register approved the incorporation by reference of a certain 
other publication listed in the AD.
    We must receive any comments on this AD by December 24, 2009.

ADDRESSES: You may send comments by any of the following methods:
    <bullet> Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
    <bullet> Fax: 202-493-2251.
    <bullet> 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.
    <bullet> 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 Boeing 
Commercial Airplanes, Attention: Data & Services Management, P.O. Box 
3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, 
extension 1, fax 206-766-5680; e-mail [email protected]; Internet 
https://www.myboeingfleet.com.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov 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: Nancy Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6440; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Discussion

    On July 10, 2008, we issued AD 2008-15-05, amendment 39-15617 (73 
FR 42259, July 21, 2008). That AD applies to all Boeing Model 737-300, 
-400, and -500 series airplanes. That AD requires inspecting to 
determine if certain carriage spindles are installed, repetitive 
inspections for corrosion and indications of corrosion on affected 
carriage spindles, and if necessary,

[[Page 57565]]

related investigative action and corrective action. That AD also 
provides optional terminating action. That AD resulted from a report of 
corrosion found on carriage spindles that are located on the outboard 
trailing edge flaps. The actions specified in that AD are intended to 
detect and correct corrosion of the carriage spindle, which could 
result in fracture. Fracture of both the inboard and outboard carriage 
spindles, in the forward ends through the large diameters, on a flap, 
could adversely affect the airplane's continued safe flight and 
landing.

Actions Since Existing AD Was Issued

    Since we issued AD 2008-15-05, we approved an alternative method of 
compliance (AMOC), dated December 8, 2008, to exclude certain carriage 
spindle serial numbers from the inspection requirements. This approval 
was given based on information received from Boeing indicating that 
only one supplier of the carriage spindles produced discrepant 
coatings, and that the carriages produced by the second supplier did 
not have this unsafe condition.
    Subsequent to the AMOC approval, we were advised that the carriages 
produced by the second supplier may have been incorrectly finished, 
leading to over-grinding of the high velocity oxy-fuel (HVOF) coating 
on the spindle. The over-grinding of the HVOF coating leads to exposure 
of the base metal, which is susceptible to corrosion. We also received 
additional reports of corrosion found on the carriage spindles that 
were excluded from the inspection requirements in the existing AD. 
Investigation of those carriage spindles revealed that discrepant 
surface finishing of the HVOF coating during the production process had 
exposed the base metal. The exposed base metal is susceptible to 
corrosion.
    Subsequently, we have determined that it is necessary to reinstate 
the inspections of certain carriage spindles because those spindles are 
subject to the same unsafe condition.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 737-57A1304, Revision 1, 
dated August 11, 2009. (We referred to Boeing Alert Service Bulletin 
737-57A1304, dated June 2, 2008, as the appropriate source of service 
information for accomplishing the required actions of AD 2008-15-05.) 
The actions specified in Revision 1 are essentially identical to those 
in Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008. 
Revision 1 references the effect of the AMOC letter discussed 
previously and adds a new table (Table 3) to reflect certain serial 
numbers that also are subject to the unsafe condition, but were 
excluded from the inspection requirements under the AMOC discussed 
previously.

FAA's Determination and Requirements of This AD

    The unsafe condition described previously is likely to exist or 
develop on other airplanes of the same type design. For this reason, we 
are issuing this AD to supersede AD 2008-15-05. This new AD retains 
certain requirements of the existing AD. This AD would also require 
accomplishing the actions specified in the Relevant Service Information 
described previously.

Interim Action

    We consider this AD interim action. We are currently considering 
requiring replacement of all HVOF-coated carriage spindles, which will 
constitute terminating action for the repetitive inspections required 
by this AD. 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 replacement.

Change to Existing AD

    This AD would retain certain requirements of AD 2008-15-05; 
however, the inspection report required by paragraph (h) of the 
existing AD is not required by this AD.
    Since AD 2008-15-05 was issued, a new paragraph (d) was added to 
provide the Air Transport Association (ATA) of America subject code. 
This code was added to make this AD parallel with other new AD actions.
    Since AD 2008-15-05 was issued, the AD format has been revised, and 
certain paragraphs have been rearranged. As a result, the corresponding 
paragraph identifiers have changed in this AD, as listed in the 
following table:

                      Revised Paragraph Identifiers
------------------------------------------------------------------------
                                           Corresponding requirement in
      Requirement in AD  2008-15-05                   this AD
------------------------------------------------------------------------
paragraph (d)...........................  paragraph (e).
paragraph (e)...........................  paragraph (f).
paragraph (f)...........................  paragraph (g).
paragraph (g)...........................  paragraph (h).
paragraph (i)...........................  paragraph (j).
paragraph (j)...........................  paragraph (k).
------------------------------------------------------------------------

FAA's Justification and Determination of the Effective Date

    We received additional reports of corrosion found on carriage 
spindles that are located on the outboard trailing edge flaps and were 
removed from the inspection requirements in the existing AD. 
Investigation of those carriage spindles revealed that discrepant 
surface finishing of the HVOF coating done during the production 
process had exposed the base metal. The exposed base metal is 
susceptible to corrosion. Corrosion occurring on the exposed base metal 
can quickly lead to cracking and full fracture of the carriage spindle. 
Fracture of both the inboard and outboard carriage spindles, in the 
forward ends through the large diameters, on a single flap, could 
adversely affect the airplane's continued safe flight and landing. 
Because of our requirement to promote safe flight of civil aircraft and 
thus, the critical need to assure the structural integrity of the 
carriage spindle 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-2009-1026; Directorate Identifier 2009-NM-197-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

[[Page 57566]]

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 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 part 39 of the Federal Aviation Regulations (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 FAA amends Sec.  39.13 by removing amendment 39-15617 (73 FR 
42259, July 21, 2008) and adding the following new AD:

2009-23-10 Boeing: Docket No. FAA-2009-1026; Directorate Identifier 
2009-NM-197-AD; Amendment 39-16084.

Effective Date

    (a) This AD becomes effective November 24, 2009.

Affected ADs

    (b) This AD supersedes AD 2008-15-05, Amendment 39-15617.

Applicability

    (c) This AD applies to all Boeing Model 737-300, -400, and -500 
series airplanes, certificated in any category.

Subject

    (d) Air Transport Association (ATA) of America Code 57: Wings.

Unsafe Condition

    (e) This AD results from the exclusion of certain carriage 
spindles from the requirements of the existing AD, and additional 
reports of corrosion found on carriage spindles that are located on 
the outboard trailing edge flaps. The Federal Aviation 
Administration is issuing this AD to detect and correct corrosion of 
the carriage spindle, which could result in fracture. Fracture of 
both the inboard and outboard carriage spindles, in the forward ends 
through the large diameters, on a flap, could adversely affect the 
airplane's continued safe flight and landing.

Compliance

    (f) 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 2008-15-05, With New Service 
Information

Inspection To Determine Affected Carriage Spindle

    (g) For all airplanes: Within 30 days after August 5, 2008 (the 
effective date of AD 2008-15-05), inspect the carriage sub-assembly 
to determine whether an affected carriage spindle with a high 
velocity oxy-fuel (HVOF) thermal coating is installed, in accordance 
with the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-57A1304, dated June 2, 2008. A review of airplane 
maintenance records is acceptable in lieu of this inspection if the 
part number and/or serial number of the carriage can be conclusively 
determined from that review. If no affected carriage spindle is 
installed, no further action is required by this paragraph.

Repetitive Inspections, Related Investigative Actions, and 
Corrective Action

    (h) For airplanes on which any affected carriage spindle was 
determined to be installed in accordance with Boeing Alert Service 
Bulletin 737-57A1304, dated June 2, 2008, as of the effective date 
of this AD; and the spindle is identified in Table 2 of Boeing 
Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009: At 
the later of the times specified in paragraphs (h)(1) and (h)(2) of 
this AD, do a detailed inspection (or, as an option for the forward 
end of the spindle only, a borescope inspection technique may be 
used) of the spindle for corrosion and potential indications of 
corrosion of the carriage spindle, and do all applicable related 
investigative and corrective actions, in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
57A1304, dated June 2, 2008; or Boeing Service Bulletin 737-57A1304, 
Revision 1, dated August 11, 2009. Do all applicable related 
investigative and corrective actions before further flight. Repeat 
the detailed inspection (or, as an option for the forward end of the 
spindle only, the borescope inspection) and certain related 
investigative actions (i.e., the gap-check or optional non-
destructive test (NDT) ultrasonic inspection) at the applicable 
compliance times specified in paragraph 1.E. of Boeing Alert Service 
Bulletin 737-57A1304, dated June 2, 2008; or Boeing Service Bulletin 
737-57A1304, Revision 1, dated August 11, 2009.
    (1) Within 30 days after August 5, 2008.
    (2) Within 90 days after the installation of a new HVOF-coated 
spindle.

    Note 1: Boeing Alert Service Bulletin 737-57A1304, dated June 2, 
2008; and Boeing Service Bulletin 737-57A1304, Revision 1, dated 
August 11, 2009; reference Boeing Alert Service Bulletin 737-
57A1277, Revision 1, dated November 25, 2003; for further guidance 
on accomplishing the related investigative actions.

New Requirements of This AD

Repetitive Inspections, Related Investigative Actions, and 
Corrective Action for Certain Airplanes

    (i) For airplanes on which a carriage spindle having a serial 
number identified in Table 3 of Appendix A of Boeing Service 
Bulletin 737-57A1304, Revision 1, dated August 11, 2009, is 
installed: At the latest of the times specified in paragraphs 
(i)(1), (i)(2), and (i)(3) of this AD, as applicable, do a detailed 
inspection (or, as an option for the forward end of the spindle 
only, a borescope inspection technique may be used) of the spindle 
for corrosion and potential indications of corrosion of the carriage 
spindle, and do all applicable related investigative and corrective 
actions, in accordance with the Accomplishment Instructions of 
Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 
2009. Do all applicable related investigative and corrective actions 
before further flight. Repeat the detailed inspection (or, as an 
option for the forward end of the spindle only, the borescope 
inspection) and related investigative actions (i.e., the gap-check 
or optional NDT ultrasonic inspection) at the applicable compliance 
times specified in paragraph 1.E. of Boeing Service Bulletin 737-
57A1304, Revision 1, dated August 11, 2009.
    (1) Within 30 days after the effective date of this AD.
    (2) Within 90 days after the installation of a new HVOF-coated 
spindle identified in Table 3 of Appendix A of Boeing Service 
Bulletin 737-57A1304, Revision 1, dated August 11, 2009.
    (3) Within 90 days after doing an inspection in accordance with 
Boeing Alert

[[Page 57567]]

Service Bulletin 737-57A1304, dated June 2, 2008.

Optional Terminating Action

    (j) Replacement of an HVOF-coated carriage spindle with a non-
HVOF coated carriage spindle, or with a serviceable HVOF-coated 
carriage spindle with an `R' suffix on the serial number, in 
accordance with Boeing Alert Service Bulletin 737-57A1304, dated 
June 2, 2008; or Boeing Service Bulletin 737-57A1304, Revision 1, 
dated August 11, 2009; terminates the requirements of this AD for 
that carriage spindle only.

Parts Installation

    (k) As of August 5, 2008, an HVOF-coated spindle without an `R' 
suffix on the serial number may be installed on an airplane provided 
the actions required by paragraph (h) or (i) of this AD, as 
applicable, are done on that spindle.

Alternative Methods of Compliance (AMOCs)

    (l)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. Send information to 
ATTN: Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, 
FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 917-6440; fax (425) 917-6590. Or, e-mail 
information to [email protected].
    (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 principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane.
    (4) AMOCs approved previously in accordance with AD 2008-15-05, 
are not approved as AMOCs for this AD.

Material Incorporated by Reference

    (m) You must use Boeing Alert Service Bulletin 737-57A1304, 
dated June 2, 2008; and Boeing Service Bulletin 737-57A1304, 
Revision 1, dated August 11, 2009; as applicable; to do the actions 
required by this AD, unless the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of Boeing Service Bulletin 737-57A1304, 
Revision 1, dated August 11, 2009, under 5 U.S.C. 552(a) and 1 CFR 
part 51.
    (2) The Director of the Federal Register previously approved the 
incorporation by reference of Boeing Alert Service Bulletin 737-
57A1304, dated June 2, 2008, on August 5, 2008 (73 FR 42259, July 
21, 2008).
    (3) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P. O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 
206-544-5000, extension 1; fax 206-766-5680; e-mail 
[email protected]; Internet https://www.myboeingfleet.com.
    (4) You may review copies of the service information at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington. For information on the availability of this material at 
the FAA, call 425-227-1221 or 425-227-1152.
    (5) You may also review copies of the service information that 
is incorporated by reference 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/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on October 26, 2009.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E9-26581 Filed 11-6-09; 8:45 am]
BILLING CODE 4910-13-P

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