
[Federal Register: October 16, 2008 (Volume 73, Number 201)]
[Proposed Rules]               
[Page 61369-61372]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr16oc08-21]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-1098; Directorate Identifier 2008-NM-108-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP 
Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-
200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. This 
proposed AD would require adding two new indicator lights on the P10 
panel to inform the captain and first officer of a low pressure 
condition in the left and right override/jettison pumps of the center 
wing tanks. This proposed AD would also require replacing the left and 
right override/jettison switches on the M154 fuel control module on the 
P4 panel with improved switches and doing the associated wiring 
changes. This proposed AD would also require a revision to the FAA-
approved maintenance program to incorporate airworthiness limitation 
No. 28-AWL-22. This proposed AD results from fuel system reviews 
conducted by the manufacturer. We are proposing this AD to prevent 
uncommanded operation of the override/jettison pumps of the center wing 
tanks, which could lead to an unwanted ignition source inside the 
center wing tank. This condition, in combination with flammable fuel 
vapors, could result in a center fuel tank explosion and consequent 
loss of the airplane.

DATES: We must receive comments on this proposed AD by December 1, 
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 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

[[Page 61370]]

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: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6501; fax (425) 917-6590.

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-2008-1098; 
Directorate Identifier 2008-NM-108-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 a latent 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 the actions identified in this AD 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.
    Currently, there are lights on the flight engineer's P4 panel to 
provide pressure indication for the override/jettison pumps of the left 
and right center wing tanks. These lights are illuminated to inform the 
flight engineer that a low pressure or no fuel flow condition exists. A 
pump uncommanded-on is an event that may result in the pump running dry 
and illumination of the associated low pressure light. This event 
requires the flight engineer to manually pull the pump circuit breaker 
to shut off the pump. To limit the potential of the pump running dry 
for an extended period of time, Boeing has found that two new indicator 
lights must be added to the forward panel on the flight deck to inform 
the captain and first officer of a low pressure condition in the 
override/jettison pumps. The P4 panel must also be modified to provide 
the flight engineer with switches to shut off the override/jettison 
pumps and the new indicator lights.
    Uncommanded operation of the override/jettison pumps of the center 
wing tanks could lead to an unwanted ignition source inside the center 
wing tank. These conditions, if not corrected, in combination with 
flammable fuel vapors, could result in a center fuel tank explosion and 
consequent loss of the airplane.

Other Related Rulemaking

    On April 28, 2008, we issued AD 2008-10-07, amendment 39-15513 (73 
FR 25977, May 8, 2008), applicable to certain Boeing Model 747-100, 
747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, 
and 747SP series airplanes. That AD requires revising the FAA-approved 
maintenance program by incorporating new airworthiness limitations 
(AWLs) for fuel tank systems to satisfy SFAR 88 requirements. That AD 
also requires the initial accomplishment of certain repetitive AWL 
inspections to phase in those inspections, and repair if necessary. As 
an optional action, that AD also allows incorporating AWL No. 28-AWL-22 
into the FAA-approved maintenance program. Incorporating AWL No. 28-
AWL-22 into the FAA-approved maintenance program in accordance with 
paragraph (g) of AD 2008-10-07 would terminate the action specified in 
paragraph (g) of this proposed AD.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-28A2288, dated 
March 20, 2008. The service bulletin describes procedures for adding 
two indicator lights on the P10 panel to inform the captain and first 
officer of a low pressure condition in the left and right override/
jettison pumps of the center wing tanks. The service bulletin also 
describes procedures for replacing the left and right override/jettison 
switches on certain M154 fuel control modules on the P4 panel with 
improved switches, and doing the associated wiring changes.
    For airplanes equipped with certain other M154 fuel control 
modules, Boeing Alert Service Bulletin 747-28A2288 refers to the BAE 
Systems service bulletins in the following table as additional sources 
of service information for replacing the switches and doing the 
associated wiring changes, as applicable:

[[Page 61371]]



                Additional Sources of Service Information
------------------------------------------------------------------------
          Service Bulletin                           Date
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BAE Systems Service Bulletin          February 16, 2006.
 65B46124-28-01.
BAE Systems Service Bulletin          March 28, 2007.
 65B46124-28-02.
BAE Systems Service Bulletin          March 28, 2007.
 65B46124-28-03.
BAE Systems Service Bulletin          February 16, 2006.
 65B46214-28-01.
BAE Systems Service Bulletin          March 28, 2007.
 65B46214-28-02.
BAE Systems Service Bulletin          March 28, 2007.
 65B46214-28-03.
------------------------------------------------------------------------

    We have also reviewed the Boeing 747-100/200/300/SP Airworthiness 
Limitations (AWLs) and Certification Maintenance Requirements (CMRs), 
D6-13747-CMR, Revision March 2008 (hereafter referred to as ``Document 
D6-13747-CMR''). (For the purposes of Document D6-13747-CMR, the Model 
747SR series airplane is basically a Model 747-100 series airplane with 
certain modifications to improve fatigue life.) Section D of Document 
D6-13747-CMR describes AWLs for fuel tank systems. Section D of 
Document D6-13747-CMR includes fuel system AWL No. 28-AWL-22, which is 
a repetitive inspection (test) to verify continued functionality of the 
low pressure indicator lights on the P10 panel for the override/
jettison pumps of the center wing tanks.

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(se) same type 
design(s). This proposed AD would require accomplishing the following 
actions:
     Adding two new indicator lights on the P10 panel to inform 
the captain and first officer of a low pressure condition in the left 
and right override/jettison pumps of the center wing tanks.
     Replacing the left and right override/jettison switches on 
the M154 fuel control module on the P4 panel with improved switches and 
doing the associated wiring changes.
     Revising the FAA-approved maintenance program to 
incorporate AWL No. 28-AWL-22, which is a repetitive inspection to 
verify continued functionality of the low pressure indicator lights on 
the P10 panel for the override/jettison pumps of the center wing tanks.

Costs of Compliance

    We estimate that this proposed AD would affect 185 airplanes of 
U.S. registry. We also estimate that it would take up to 28 work-hours 
per product to comply with this proposed AD. The average labor rate is 
$80 per work-hour. Required parts would cost up to $2,668 per product. 
Based on these figures, we estimate the cost of this proposed AD to the 
U.S. operators up to $907,980, or $4,908 per product.

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 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, 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-2008-1098; Directorate Identifier 2008-NM-
108-AD.

Comments Due Date

    (a) We must receive comments by December 1, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B 
SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series 
airplanes, certificated in any category; as identified in Boeing 
Alert Service Bulletin 747-28A2288, dated March 20, 2008.

    Note 1: This AD requires revisions to certain operator 
maintenance documents to include a new inspection. Compliance with 
this inspection is required by 14 CFR 91.403(c). For airplanes that 
have been previously modified, altered, or repaired in the areas 
addressed by this inspection, 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 (AMOC) 
according to paragraph (j) of this AD. The request should include a 
description of changes to the required inspection that will ensure 
the continued operational safety of the airplane.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent uncommanded 
operation of the override/jettison pumps of

[[Page 61372]]

the center wing tanks, which could lead to an unwanted ignition 
source inside the center wing tank. This condition, in combination 
with flammable fuel vapors, could result in a center fuel tank 
explosion and consequent loss of the airplane.

Compliance

    (e) Comply with this AD within the compliance times specified, 
unless already done.

Installation of Indicator Lights and Replacement of Switches

    (f) Within 36 months after the effective date of this AD: Add 
two new indicator lights on the P10 panel to inform the captain and 
first officer of a low pressure condition in the left and right 
override/jettison pumps of the center wing tanks; and replace the 
left and right override/jettison switches on the M154 fuel control 
module on the P4 panel with improved switches and do the associated 
wiring changes; by accomplishing all of the applicable actions 
specified in the Accomplishment Instructions of Boeing Alert Service 
Bulletin 747-28A2288, dated March 20, 2008.

    Note 2: For airplanes equipped with certain M154 fuel control 
modules, paragraph 2.C.2 of Boeing Alert Service Bulletin 747-
28A2288 refers to the BAE Systems service bulletins identified in 
Table 1 of this AD, as applicable, as additional sources of service 
information for replacing the switches.


           Table 1--Additional Sources of Service Information
------------------------------------------------------------------------
          Service Bulletin                           Date
------------------------------------------------------------------------
BAE Systems Service Bulletin          February 16, 2006.
 65B46124-28-01.
BAE Systems Service Bulletin          March 28, 2007.
 65B46124-28-02.
BAE Systems Service Bulletin          March 28, 2007.
 65B46124-28-03.
BAE Systems Service Bulletin          February 16, 2006.
 65B46214-28-01.
BAE Systems Service Bulletin          March 28, 2007.
 65B46214-28-02.
BAE Systems Service Bulletin          March 28, 2007.
 65B46214-28-03.
------------------------------------------------------------------------

Maintenance Program Revision

    (g) Concurrently with accomplishing the actions required by 
paragraph (f) of this AD, revise the FAA-approved maintenance 
program by incorporating Airworthiness Limitation (AWL) No. 28-AWL-
22 of Section D of the Boeing 747-100/200/300/SP Airworthiness 
Limitations (AWLs) and Certification Maintenance Requirements 
(CMRs), D6-13747-CMR, Revision March 2008.

No Alternative Inspections or Inspection Intervals

    (h) After accomplishing the action specified in paragraph (g) of 
this AD, no alternative inspections or inspection intervals may be 
used unless the inspections or inspection intervals are approved as 
an AMOC in accordance with the procedures specified in paragraph (j) 
of this AD.

Terminating Action for Maintenance Program Revision

    (i) Incorporating AWL No. 28-AWL-22 into the FAA-approved 
maintenance program in accordance with paragraph (g) of AD 2008-10-
07, amendment 39-15513, terminates the action required by paragraph 
(g) of this AD.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle ACO, FAA, ATTN: Sulmo Mariano, 
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle ACO, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6501; fax (425) 917-659; 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 October 7, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-24542 Filed 10-15-08; 8:45 am]

BILLING CODE 4910-13-P
