Document ID: FAA-2007-0004-0061
Agency: faa
Document Type: Notice
Title: Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800 and -900 Series Airplanes
Posted Date: 2007-08-31T04:00Z

[Federal Register: August 31, 2007 (Volume 72, Number 169)]
[Proposed Rules]               
[Page 50292-50294]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr31au07-23]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-29087; Directorate Identifier 2007-NM-094-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800 
and -900 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 Boeing Model 737-600, -700, -700C, -800 and -900 series 
airplanes. This proposed AD would require repetitive lubrication of the 
left and right main landing gear (MLG) forward trunnion pins. This 
proposed AD would also require an inspection for discrepancies of the 
transition radius of the MLG forward trunnion pins, and repair or 
replacement if necessary. This proposed AD would also require a one-
time inspection for discrepancies of the lead-in chamfer and cross-bolt 
bore, and repair or replacement if necessary. Doing the applicable 
inspections and repairs/replacements, or overhauling the trunnion pins 
ends the repetitive lubrication requirements of this proposed AD. This 
proposed AD results from a report that the protective finishes on the 
forward trunnion pins for the left and right MLG might have been 
damaged during final assembly. We are proposing this AD to prevent 
cracking of the forward trunnion pin, which could result in fracture of 
the pin and consequent collapse of the MLG.

DATES: We must receive comments on this proposed AD by October 15, 
2007.

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: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Fax: (202) 493-2251.
     Hand Delivery: Room W12-140 on the ground floor of the 
West Building, 1200 New Jersey Avenue, SE., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for the service information identified in this 
proposed AD.

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:

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-
29087; Directorate Identifier 2007-NM-094-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 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 Operations office between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The 
Docket Operations office (telephone (800) 647-5527) is located on the 
ground floor of the West Building at the street address stated in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after the Docket Management System receives them.

[[Page 50293]]

Discussion

    We have received a report indicating that the protective finishes 
on the forward trunnion pins for the main landing gear (MLG) might have 
been damaged during final assembly of Boeing Model 737-600, -700, -
700C, -800 and -900 series airplanes. The protective coating could be 
damaged at two locations because of the use of an unauthorized process, 
and damaged at one location because the pin was not handled correctly. 
Therefore, it is possible that these trunnion pins have been delivered 
to operators with compromised corrosion protection in these critical 
areas:
     The cross-bolt bore and outer diameter surface.
     The lead-in chamfer and outer diameter surface.
     The transition radius between the chrome-plated outer 
diameter and the spherical ball bearing surface.
    Damage to the protective finish puts the base metal of the trunnion 
pin at risk from corrosion pitting. This condition, if not corrected, 
could lead to cracking of the forward trunnion pin, which could result 
in fracture of the pin and consequent collapse of the MLG.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 737-32-1376, Revision 1, 
dated March 19, 2007. The service bulletin describes procedures for 
repetitive lubrication of the MLG forward trunnion pins. The service 
bulletin states that accomplishing the inspections and applicable 
repairs/replacements described below, or overhauling the trunnion pins 
in accordance with Boeing 737 Component Maintenance Manual 57-15-01, 
eliminates the need for the repetitive lubrication.
    The service bulletin also describes procedures for an inspection 
for discrepancies (corrosion, finish damage, surface deformation, or 
scratches) of the transition radius. If any discrepancy is found, the 
service bulletin specifies repairing or replacing the trunnion pin, as 
applicable, depending on the type of discrepancy found. The repair 
includes blending and restoring the protective finish. If the trunnion 
pin is not replaced, the service bulletin specifies an additional 
inspection for discrepancies of the lead-in chamfer and the cross-bolt 
bore. If any discrepancy is found, the service bulletin specifies 
repairing or replacing the trunnion pin, as applicable, depending on 
the type of discrepancy found.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Difference Between the Proposed AD and the Service Bulletin.''

Difference Between the Proposed AD and the Service Bulletin

    Although Boeing Service Bulletin 737-32-1376, Revision 1, dated 
March 19, 2007, specifies to send inspection reports to the 
manufacturer, this proposed AD would not require that action.

Costs of Compliance

    There are about 890 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD. The average labor rate 
is $80 per work hour.

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                Number of
                                      Work                                        U.S.-
              Action                 hours      Parts      Cost per airplane    registered       Fleet cost
                                                                                airplanes
----------------------------------------------------------------------------------------------------------------
Repetitive lubrication...........          1         $0  $80, per lubrication          300  $24,000, per
                                                          cycle.                             lubrication cycle.
Inspections......................          4          0  320.................          300  $96,000.
----------------------------------------------------------------------------------------------------------------

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:

[[Page 50294]]

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):

Boeing: Docket No. FAA-2007-29087; Directorate Identifier 2007-NM-
094-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by October 
15, 2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-600, -700, -700C, -800 
and -900 series airplanes, certificated in any category, as 
identified in Boeing Service Bulletin 737-32-1376, Revision 1, dated 
March 19, 2007.

Unsafe Condition

    (d) This AD results from a report that the protective finishes 
on the forward trunnion pins for the left and right main landing 
gear (MLG) might have been damaged during final assembly. We are 
issuing this AD to prevent cracking of the forward trunnion pin, 
which could result in fracture of the pin and consequent collapse of 
the MLG.

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.

Lubrication or Overhaul

    (f) Within 30 days after the effective date of this AD: 
Lubricate the left and right MLG forward trunnion pins in accordance 
with the Accomplishment Instructions of Boeing Service Bulletin 737-
32-1376, Revision 1, dated March 19, 2007. Repeat the lubrication at 
intervals not to exceed 30 days until all applicable requirements of 
paragraphs (g) and (h) of this AD have been accomplished. 
Overhauling the trunnion pin as given in the Accomplishment 
Instructions of Boeing Service Bulletin 737-32-1376, Revision 1, 
ends the repetitive lubrication requirements of this paragraph for 
that pin.

Inspection and Corrective Actions

    (g) Within 60 months after the date of issuance of the original 
standard airworthiness certificate or date of issuance of the 
original standard export certificate of airworthiness, or within 6 
months after the effective date of this AD, whichever occurs later: 
Do a detailed inspection for discrepancies (corrosion, finish 
damage, surface deformation, or scratches) of the transition radius 
of the left and right MLG trunnion pin; and if any discrepancy is 
found, repair or replace the trunnion pin before further flight. Do 
all actions in accordance with the Accomplishment Instructions of 
Boeing Service Bulletin 737-32-1376, Revision 1, dated March 19, 
2007.
    (h) For any airplane on which a trunnion pin is not replaced in 
accordance with paragraph (g) of this AD, within 96 months after the 
date of issuance of the original standard airworthiness certificate 
or date of issuance of the original standard export certificate of 
airworthiness, or within 12 months after the effective date of this 
AD, whichever occurs later: Do a detailed inspection for 
discrepancies of the lead-in chamfer and cross-bolt bore; and if any 
discrepancy is found, repair or replace the trunnion pin before 
further flight. Do all actions in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 737-32-1376, Revision 1, 
dated March 19, 2007.

No Report Required

    (i) Although Boeing Service Bulletin 737-32-1376, Revision 1, 
dated March 19, 2007, specifies to send inspection reports to the 
manufacturer, this AD does not include that requirement.

Credit for Actions Done Using Previous Issue of Service Information

    (j) Actions done before the effective date of this AD in 
accordance with Boeing Service Bulletin 737-32-1376, dated May 12, 
2005, are acceptable for compliance with the corresponding actions 
of this AD.

Alternative Methods of Compliance (AMOCs)

    (k)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
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.
    (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, and the approval must specifically refer to this 
AD.

    Issued in Renton, Washington, on August 17, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-17285 Filed 8-30-07; 8:45 am]

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