[Federal Register Volume 74, Number 109 (Tuesday, June 9, 2009)]
[Proposed Rules]
[Pages 27254-27257]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-13494]


========================================================================
Proposed Rules
                                                Federal Register
________________________________________________________________________

This section of the FEDERAL REGISTER contains notices to the public of 
the proposed issuance of rules and regulations. The purpose of these 
notices is to give interested persons an opportunity to participate in 
the rule making prior to the adoption of the final rules.

========================================================================


Federal Register / Vol. 74, No. 109 / Tuesday, June 9, 2009 / 
Proposed Rules

[[Page 27254]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2009-0521; Directorate Identifier 2008-NM-187-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes Equipped With a Digital Transient Suppression Device 
(DTSD) Installed in Accordance With Supplemental Type Certificate (STC) 
ST00127BO

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Boeing Model 737-300, -400, and -500 series airplanes. This 
proposed AD would require revising the maintenance program to include 
new fuel system limitations for airplanes modified in accordance with 
STC ST00127BO. This AD also requires inspections and checks of the 
DTSDs and corrective actions, if necessary. This proposed AD results 
from fuel system reviews conducted by the manufacturer. We are 
proposing this AD to prevent a potential of ignition sources inside 
fuel tanks, which, in combination with flammable fuel vapors, could 
result in a fuel tank fire or explosion and consequent loss of the 
airplane.

DATES: We must receive comments on this proposed AD by July 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 Goodrich 
Corporation, Fuel and Utility Systems, 100 Panton Road, Vergennes, 
Vermont 05491-1008; telephone 802-877-4476; e-mail 
<a href="/cdn-cgi/l/email-protection#523e35367c0637313a022730217c1d3339243b3e3e3712353d3d36203b313a7c313d3f"><span class="__cf_email__" data-cfemail="fd919a99d3a9989e95ad889f8ed3b29c968b94919198bd9a9292998f949e95d39e9290">[email protected]</span></a>; Internet http://www.goodrich.com/TechPubs. You may review copies of the referenced 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.

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: Marc Ronell, Aerospace Engineer, ANE-
150, FAA, Boston Aircraft Certification Office, 12 New England 
Executive Park, Burlington, Massachusetts 01803; telephone (781) 238-
7776; fax (781) 238-7170.

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-2009-0521; 
Directorate Identifier 2008-NM-187-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

    The FAA has examined the underlying safety issues involved in fuel 
tank explosions on several large transport airplanes, including the 
adequacy of existing regulations, the service history of airplanes 
subject to those regulations, and existing maintenance practices for 
fuel tank systems. As a result of those findings, we issued a 
regulation titled ``Transport Airplane Fuel Tank System Design Review, 
Flammability Reduction and Maintenance and Inspection Requirements'' 
(66 FR 23086, May 7, 2001). In addition to new airworthiness standards 
for transport airplanes and new maintenance requirements, this rule 
included Special Federal Aviation Regulation No. 88 (``SFAR 88,'' 
Amendment 21-78, and subsequent Amendments 21-82 and 21-83).
    Among other actions, SFAR 88 requires certain type design (i.e., 
type certificate (TC) and supplemental type certificate (STC)) holders 
to substantiate that their fuel tank systems can prevent ignition 
sources in the fuel tanks. This requirement applies to type design 
holders for large turbine-powered transport airplanes and for 
subsequent modifications to those airplanes. It requires them to 
perform design reviews and to develop design changes and maintenance 
procedures if their designs do not meet the new fuel tank safety 
standards. As explained in the preamble to the rule, we intended to 
adopt airworthiness directives to mandate any changes found necessary 
to address unsafe conditions identified as a result of these reviews.
    In evaluating these design reviews, we have established four 
criteria intended to define the unsafe conditions associated with fuel 
tank systems that require corrective actions. The percentage of 
operating time during which fuel tanks are exposed to flammable 
conditions is one of these criteria. The other three criteria address 
the failure types under evaluation: single failures, single failures in 
combination with another latent

[[Page 27255]]

condition(s), and in-service failure experience. For all four criteria, 
the evaluations included consideration of previous actions taken that 
may mitigate the need for further action.
    We have determined that revising the maintenance program to include 
new fuel system limitations for airplanes modified in accordance with 
Supplemental Type Certificate (STC) ST00127BO are necessary to reduce 
the potential of ignition sources inside fuel tanks, which, in 
combination with flammable fuel vapors, could result in fuel tank 
explosions and consequent loss of the airplane.

Relevant Service Information

    We have reviewed Goodrich Instructions for Continued Airworthiness 
(ICA) for Boeing Model 737-300/400/500 Airplanes, Document T2007-0010-
0101, Revision D, dated January 16, 2007. The ICA includes Section 
2.2.3, ``Scheduled Inspections/Operational Checks,'' and Section 10.1, 
``Fuel System Limitations'' (hereafter referred to as ``the 
instructions''). These fuel system limitations are identified as 
critical design configuration control limitations (CDCCLs), which are 
limitation requirements to preserve a critical ignition source 
prevention feature of the fuel tank system design that is necessary to 
prevent the occurrence of an unsafe condition. The purpose of a CDCCL 
is to provide instructions to retain the critical ignition source 
prevention feature during configuration changes that may be caused by 
alterations, repairs, or maintenance actions. A CDCCL is not a periodic 
inspection.
    The scheduled inspections/operational checks are periodic 
inspections/checks of certain features for latent failures that could 
contribute to an ignition source. The instructions describe the 
following procedures to detect discrepancies of the following 
components of the left wing, right wing, and center tanks:
    <bullet> Digital transient suppression devices (DTSD): Initial 
operational check.
    <bullet> DTSD safe-side harnesses: Inspection for critical bond 
damage, which includes measuring the bonding resistance across the 
ground strap and verifying the resistance is less than 2.0 milliohms.
    <bullet> DTSD safe-side harnesses: Inspection for physical 
separation of the harness from other airplane wiring, hydraulic tubing, 
structure, control cables, and bleed air ducts. Separation is required 
to ensure that threat conditions do not develop that could compromise 
the safety of the wiring entering the fuel tank.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design. 
This proposed AD would require revising the maintenance program to 
include the scheduled inspections/operational checks specified in 
Section 2.2.3 and the fuel system limitations specified in Section 10.1 
of the Goodrich ICA for airplanes modified in accordance with STC 
ST00127BO, and accomplishing the actions specified in the scheduled 
inspections/operational checks and the CDCCLs described previously, 
except as described below in ``Differences Between the Instructions and 
This Proposed AD.''

Differences Between the Instructions and This Proposed AD

    The instructions do not specify an initial compliance time for 
doing the scheduled inspections/operational checks. This proposed AD 
would require an operational check of the DTSDs prior to the 
accumulation of 39,000 flight hours after modification in accordance 
with STC ST00127BO, or within 12 months, whichever occurs later. This 
proposed AD would require a general visual inspection for critical bond 
damage of the DTSD safe-side harnesses (critical bond damage includes 
measuring the bonding resistance across the ground strap and verifying 
the resistance is less than 2.0 milliohms) prior to the accumulation of 
4,000 flight hours after modification in accordance with STC ST00127BO, 
or within 6 months, whichever occurs later. This proposed AD would also 
require a general visual inspection for physical separation of the DTSD 
safe-side harnesses from other airplane wiring, hydraulic tubing, 
structure, control cables, and bleed air ducts prior to the 
accumulation of 24,000 flight hours after modification in accordance 
with STC ST00127BO, or within 12 months, whichever occurs later.
    The instructions also do not specify corrective actions if any 
discrepancy is found. This proposed AD would require that if any 
discrepancy is found, applicable corrective actions must be done in 
accordance with the applicable section of the Goodrich Aircraft 
Maintenance Manual (AMM) Supplement with Wiring Diagrams for 737-300/-
400/-500 FQIS with Goodrich Digital Indicators and Transient 
Suppression Device, STC Number: STC ST00127BO, Revision 5, dated 
December 20, 2006, as specified in the instructions.

Costs of Compliance

    We estimate that this proposed AD would affect 12 airplanes of U.S. 
registry. 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
------------------------------------------------------------------------
                                                  Cost per    Fleet cost
              Action                Work hours  product ($)      ($)
------------------------------------------------------------------------
Revision to maintenance program..            8          640        7,680
Operational check, per cycle.....            1           80          960
Bond damage inspection, per cycle            1           80          960
Separation inspection, per cycle.            1           80          960
------------------------------------------------------------------------

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

[[Page 27256]]

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 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 this 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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, 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 FAA amends Sec.  39.13 by adding the following new AD:

Boeing: Docket No. FAA-2009-0521; Directorate Identifier 2008-NM-
187-AD.

Comments Due Date

    (a) We must receive comments by July 24, 2009.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-300, -400, and -500 
series airplanes, certificated in any category, equipped with a 
digital transient suppression device (DTSD) installed in accordance 
with Supplemental Type Certificate (STC) STC ST00127BO.

    Note 1: This AD requires revisions to certain operator 
maintenance documents to include new inspections. Compliance with 
these inspections is required by 14 CFR 91.403(c). For airplanes 
that have been previously modified, altered, or repaired in the 
areas addressed by these inspections, the operator may not be able 
to accomplish the inspections described in the revisions. In this 
situation, to comply with 14 CFR 91.403(c), the operator must 
request approval for an alternative method of compliance according 
to paragraph (m) of this AD. The request should include a 
description of changes to the required inspections that will ensure 
the continued operational safety of the airplane.

Subject

    (d) Air Transport Association (ATA) of America Code 28: Fuel.

Unsafe Condition

    (e) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent a potential of 
ignition sources inside fuel tanks, which in combination with 
flammable fuel vapors, could result in a fuel tank fire or explosion 
and consequent loss of the airplane.

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.

Revision to the Maintenance Program To Add CDCCLs

    (g) Within 30 days after the effective date of this AD, revise 
the maintenance program to incorporate the fuel system limitations 
specified in Section 10.1 of the Goodrich Instructions for Continued 
Airworthiness (ICA) for Boeing Model 737-300/400/500 Airplanes, 
Document T2007-0010-0101, Revision D, dated January 16, 2007.

Revision to the Maintenance Program To Add Scheduled Inspections/
Operational Checks

    (h) Within 30 days after the effective date of this AD: Revise 
the maintenance program to incorporate the scheduled inspections/
operational checks specified in Section 2.2.3 of the Goodrich ICA 
for Boeing Model 737-300/400/500 Airplanes, Document T2007-0010-
0101, Revision D, dated January 16, 2007; except that the initial 
inspections/checks required by paragraphs (i), (j), and (k) of this 
AD must be done at the compliance times specified in those 
paragraphs. Repeat the inspections/checks thereafter at the 
applicable compliance times in the column, ``Frequency,'' of the 
table specified in Section 2.2.3 of the Goodrich ICA for Boeing 
Model 737-300/400/500 Airplanes, Document T2007-0010-0101, Revision 
D, dated January 16, 2007.

Initial Inspections and Repair if Necessary

    (i) Prior to the accumulation of 39,000 flight hours after 
modification in accordance with STC ST00127BO, or within 12 months 
after the effective date of this AD, whichever occurs later: Do an 
operational check of the digital transient suppression devices 
(DTSD) in accordance with Section 2.2.3., ``Scheduled Inspections/
Operational Checks,'' of the Goodrich ICA, for Boeing Model 737-300/
400/500 Airplanes, Document T2007-0010-0101, Revision D, dated 
January 16, 2007. If the DTSD fails the operational check, repair 
before further flight in accordance with the section of the Goodrich 
Aircraft Maintenance Manual (AMM) Supplement with Wiring Diagrams 
for 737-300/-400/-500 FQIS with Goodrich Digital Indicators and 
Transient Suppression Device, STC Number: STC ST00127BO, Revision 5, 
dated December 20, 2006, that corresponds to the operational check 
specified in Goodrich ICA for Boeing Model 737-300/400/500 
Airplanes, Document T2007-0010-0101, Revision D, dated January 16, 
2007.
    (j) Prior to the accumulation of 4,000 flight hours after 
modification in accordance with STC ST00127BO, or within 6 months 
after the effective date of this AD, whichever occurs later: Do a 
general visual inspection for critical bond damage of the DTSD safe-
side harnesses (critical bond damage includes measuring the bonding 
resistance across the ground strap and verifying the resistance is 
less than 2.0 milliohms), in accordance with Section 2.2.3., 
``Scheduled Inspections/Operational Checks,'' of Goodrich ICA for 
Boeing Model 737-300/400/500 Airplanes, Document T2007-0010-0101, 
Revision D, dated January 16, 2007, which includes Items 5, 6, 7, 
and 8 of Table 6 in Section 10.1, ``Fuel System Limitations.'' If 
any damage is found, repair before further flight in accordance with 
the section of the Goodrich Aircraft Maintenance Manual Supplement 
with Wiring Diagrams for 737-300/-400/-500 FQIS with Goodrich 
Digital Indicators and Transient Suppression Device, STC Number: STC 
ST00127BO, Revision 5, dated December 20, 2006, that corresponds to 
the general visual inspection specified in Goodrich ICA for Boeing 
Model 737-300/400/500 Airplanes, Document T2007-0010-0101, Revision 
D, dated January 16, 2007.
    (k) Prior to the accumulation of 24,000 flight hours after 
modification in accordance with STC ST00127BO, or within 12 months 
after the effective date of this AD, whichever occurs later: Do a 
general visual inspection for physical separation of the DTSD safe-
side harnesses from other airplane wiring, hydraulic tubing, 
structure, control cables, and bleed air ducts, in accordance with 
Section 2.2.3., ``Scheduled Inspections/Operational Checks,'' of the 
Goodrich ICA for Boeing Model 737-300/400/500 Airplanes, Document 
T2007-0010-0101, Revision D, dated January 16, 2007. If any damage 
is found, repair before further flight in accordance with the 
section of the Goodrich Aircraft Maintenance Manual Supplement with 
Wiring Diagrams for 737-300/-400/ -500 FQIS with Goodrich Digital 
Indicators and Transient Suppression Device, STC Number: STC 
ST00127BO, Revision 5, dated

[[Page 27257]]

December 20, 2006, that corresponds to the general visual inspection 
specified in Goodrich ICA for Boeing Model 737-300/400/500 
Airplanes, Document T2007-0010-0101, Revision D, dated January 16, 
2007.

No Alternative Inspections/Checks, Inspection/Check Intervals, or 
CDCCLs

    (l) After accomplishing the actions specified in paragraphs (g) 
and (h) of this AD, no alternative inspections/checks, inspection/
check intervals, or CDCCLs may be used unless the inspections/
checks, intervals, or CDCCLs are approved as an Alternative Method 
of Compliance (AMOC) in accordance with the procedures specified in 
paragraph (m) of this AD.

AMOCs

    (m)(1) The Manager, Boston 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: Marc Ronell, Aerospace Engineer, ANE-150, FAA, Boston Aircraft 
Certification Office, 12 New England Executive Park, Burlington, 
Massachusetts 01803; telephone (781) 238-7776; fax (781) 238-7170.
    (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.


    Issued in Renton, Washington, on June 2, 2009.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E9-13494 Filed 6-8-09; 8:45 am]
BILLING CODE 4910-13-P


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