[Federal Register Volume 73, Number 171 (Wednesday, September 3, 2008)]
[Proposed Rules]
[Pages 51382-51384]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-20341]



[[Page 51382]]

=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-25001; Directorate Identifier 2006-NM-079-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -
800, -900 and -900ER Series Airplanes

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

ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of 
comment period.

-----------------------------------------------------------------------

SUMMARY: The FAA is revising an earlier proposed airworthiness 
directive (AD) for certain Boeing Model 737-600, -700, -700C, -800 and 
-900 series airplanes. The original NPRM would have required replacing 
the aero/fire seals of the blocker doors on the thrust reverser torque 
boxes on the engines with new, improved aero/fire seals. The original 
NPRM resulted from a report that the top three inches of the aero/fire 
seals of the blocker doors on the thrust reverser torque boxes are not 
fireproof. This action revises the original NPRM by adding airplanes to 
the applicability statement and requiring a one-time inspection to 
determine the part numbers of the aero/fire seals. We are proposing 
this supplemental NPRM to prevent a fire in the fan compartment (a fire 
zone) from migrating through the seal to a flammable fluid in the 
thrust reverser actuator compartment (a flammable fluid leakage zone), 
which could result in an uncontrolled fire.

DATES: We must receive comments on this supplemental NPRM by September 
29, 2008.

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.
    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 proposed AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.

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: Samuel Spitzer, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue SW., Renton, Washington 98057-3356; telephone 
(425) 917-6510; 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 under the ADDRESSES section. Include ``Docket No. FAA-2006-
25001; Directorate Identifier 2006-NM-079-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

    We issued a notice of proposed rulemaking (NPRM) (the ``original 
NPRM'') to amend 14 CFR part 39 to include an airworthiness directive 
(AD) that would apply to certain Boeing Model 737-600, -700, -700C, -
800 and -900 series airplanes. The original NPRM was published in the 
Federal Register on June 13, 2006 (71 FR 34025). The original NPRM 
proposed to require replacing the aero/fire seals of the blocker doors 
on the thrust reverser torque boxes on the engines with new, improved 
aero/fire seals.

Actions Since Original NPRM Was Issued

    Since we issued the original NPRM, we have received information on 
the rotability of the affected aero/fire seals. Also, Model 737-900ER 
series airplanes have been added to the U.S. type certificate data 
sheet and could be affected by the rotability of the seals.

Comments

    We have considered the following comments on the original NPRM.

Support for the Original NPRM

    Boeing concurs with the contents of the original NPRM.

Request To Revise the Applicability Statement To Address Rotable Parts

    AirTran Airways requests that we revise the applicability statement 
of the original NPRM to apply to the part number/serial number of the 
affected thrust reverser assembly instead of the serial number of 
airplanes. AirTran is concerned that the proposed applicability does 
not address the possibility that an affected thrust reverser assembly 
might be installed on an airplane not addressed in that applicability 
statement. AirTran states that the thrust reverser assembly is a 
rotable component, which can be removed from an airplane affected by 
this proposed AD and installed on an airplane not affected by this 
proposed AD. AirTran also notes that the thrust reverser assemblies 
have serialized numbers and are tracked by most airlines.
    We agree that it is possible to rotate the affected component onto 
another Model 737-600, -700, -700C, -800, -900, or -900ER series 
airplane that is not affected by the applicability proposed in the 
original NPRM. We have revised the applicability statement in this 
supplemental NPRM to apply to all Model 737-600, -700, -700C, -800, -
900 and -900ER series airplanes. We have also added a new paragraph (f) 
to this supplemental NPRM to require a record check or inspection to 
determine the part number of the installed assembly. If an affected 
part number is installed, or the part number cannot be confirmed, then 
operators would be required to replace the assemblies. We have 
coordinated this issue with Boeing.

Request To Address Spare Parts

    AirTran notes that the original NPRM does not address thrust 
reverser assemblies that were purchased as spare parts. AirTran states 
that the original NPRM does not require any modifications to any thrust 
reverser

[[Page 51383]]

assembly not currently installed on an airplane.
    We infer that AirTran is concerned about the possibility that an 
affected and unmodified spare thrust reverser assembly may be installed 
on an airplane.We do not agree that revising the supplemental NPRM to 
address spare parts is necessary. We have confirmation from Boeing that 
all affected spare assemblies have been purged from the parts supply 
system. In addition, no affected/unsafe part is allowed to be installed 
on an airplane after the compliance time of an AD has passed. We have 
revised this supplemental NPRM to address the rotability concern 
expressed in the previous comment. For these reasons, we consider 
revising the AD to address spare parts unnecessary. We have not changed 
the supplemental NPRM in this regard.

Request To Incorporate by Reference During NPRM Process

    The Modification and Replacement Parts Association (MARPA) requests 
that the applicable service information be incorporated by reference in 
the NPRM phase of rulemaking and posted on the Federal Docket 
Management System (FDMS) for public access. MARPA states that since the 
service information has additional information that is not public, the 
proposed rule is not enforceable.
    We do not agree that documents should be incorporated by reference 
during the NPRM phase of rulemaking. The Office of the Federal Register 
requires that documents that are necessary to accomplish the 
requirements of the AD be incorporated by reference during the final 
rule phase of rulemaking. This supplementary NPRM is not a final rule 
and does not incorporate the relevant service information by reference. 
Further, we point out that while documents that are incorporated by 
reference do become public information, they do not lose their 
copyright protection. For that reason, we advise the public to contact 
the manufacturer to obtain copies of the referenced service 
information.
    In regard to the commenter's request to post service bulletins on 
the Department of Transportation's FDMS, we are currently in the 
process of reviewing issues surrounding the posting of service 
information on-line as part of an AD docket. Once we have thoroughly 
examined all aspects of this issue and have made a final determination, 
we will consider whether our current practice needs to be revised. No 
change to the supplemental NPRM is necessary in this regard.

Request To Address Defective Parts Manufacturer Approval (PMA) Parts

    The same commenter also requests that the Transport Airplane 
Directorate (TAD) develop a policy to address possible defective or 
replacement PMA alternative parts, regardless of the manufacturing 
source (original equipment manufacturer (OEM), PMA, or repair station), 
so that all defective PMA parts are also subject to the proposed AD and 
are removed from the parts stream.
    The FAA recognizes the need for standardization of this issue and 
is currently in the process of reviewing issues that address the use of 
PMAs in ADs at the national level. However, the Transport Airplane 
Directorate considers that to delay this particular AD action would be 
inappropriate, since we have determined that an unsafe condition exists 
and that replacement of certain parts must be accomplished to ensure 
continued safety. Therefore, no change has been made to the 
supplemental NPRM in this regard.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

    We are proposing this supplemental NPRM because we evaluated all 
pertinent information and determined an unsafe condition exists and is 
likely to exist or develop on other products of the same type design. 
Certain changes described above expand the scope of the original NPRM. 
As a result, we have determined that it is necessary to reopen the 
comment period to provide additional opportunity for the public to 
comment on this supplemental NPRM.

Costs of Compliance

    There are about 2,442 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.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                        Number of U.S.-
                      Action                           Work hours     Average labor        Parts           Cost per        registered       Fleet cost
                                                                      rate per hour                        airplane        airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspection to determine part number (new proposed                1              $80               $0              $80              803          $64,240
 action)..........................................
--------------------------------------------------------------------------------------------------------------------------------------------------------

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 supplemental NPRM and placed it in the AD docket. See 
the ADDRESSES section for a location to examine the regulatory 
evaluation.

[[Page 51384]]

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):

Boeing: Docket No. FAA-2006-25001; Directorate Identifier 2006-NM-
079-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by September 
29, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Boeing Model 737-600, -700, -700C, -
800, -900 and -900ER series airplanes, certificated in any category.

Unsafe Condition

    (d) This AD results from a report that the top three inches of 
the aero/fire seals of the blocker doors on the thrust reverser 
torque boxes are not fireproof. We are issuing this AD to prevent a 
fire in the fan compartment (a fire zone) from migrating through the 
seal to a flammable fluid in the thrust reverser actuator 
compartment (a flammable fluid leakage zone), which could result in 
an uncontrolled fire.

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 To Determine Part Number (P/N)

    (f) Within 60 months or 8,200 flight cycles after the effective 
date of this AD, whichever occurs first: Perform a one-time detailed 
inspection to determine the color of the aero/fire seals of the 
blocker doors on the thrust reverser torque boxes on the engines. 
For any aero/fire seal having a completely gray color (which is the 
color of seals with P/N 315A2245-1 or 315A2245-2), with no red at 
the upper end of the seal, do the actions specified in paragraph (g) 
of this AD. For any aero/fire seal having a red color at the upper 
end of the seal (which indicates a different part number), no 
further action is required by this AD. A review of airplane 
maintenance records is acceptable in lieu of this inspection if the 
part number of the correct aero/fire seals (P/Ns 315A2245-7 or -8) 
can be conclusively determined to be installed from that review.

    Note 1: For the purposes of this AD, a detailed inspection is: 
``An intensive examination of a specific item, installation, or 
assembly to detect damage, failure, or irregularity. Available 
lighting is normally supplemented with a direct source of good 
lighting at an intensity deemed appropriate. Inspection aids such as 
mirror, magnifying lenses, etc., may be necessary. Surface cleaning 
and elaborate procedures may be required.''

Replace the Aero/Fire Seals

    (g) For any aero/fire seal identified during the inspection/
records check in paragraph (f) of this AD as having an affected P/N: 
Within 60 months or 8,200 flight cycles after the effective date of 
this AD, whichever occurs first, replace the aero/fire seals of the 
blocker doors on the thrust reverser torque boxes on the engines 
with new, improved aero/fire seals in accordance with the 
Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 737-78-1074, Revision 1, dated September 15, 2005.

Credit for Actions Done Using Previous Service Information

    (h) Replacements done before the effective date of this AD in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-78-1074, dated April 7, 2005, are 
acceptable for compliance with the requirements of paragraph (g) of 
this AD.

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle Aircraft Certification Office, FAA, 
ATTN: Samuel Spitzer, Aerospace Engineer, Propulsion Branch, ANM-
140S, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; 
telephone (425) 917-6510; fax (425) 917-6590; has the authority to 
approve AMOCs for this AD, if requested using 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.

    Issued in Renton, Washington, on August 25, 2008.
Dionne Palermo,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-20341 Filed 9-2-08; 8:45 am]
BILLING CODE 4910-13-P