
[Federal Register: August 7, 2008 (Volume 73, Number 153)]
[Proposed Rules]               
[Page 45893-45895]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr07au08-16]                         

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0847; Directorate Identifier 2008-NM-056-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 777 Airplanes

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 777 airplanes. This proposed AD would require 
doing an inspection of the motor operated valve (MOV) actuators of the 
main and center fuel tanks for a certain part number; replacing the MOV 
actuator with a new MOV actuator if necessary; and measuring the 
electrical resistance of the bond from the adapter plate to the 
airplane structure, and corrective actions if necessary. This proposed 
AD would also require revising the Airworthiness Limitations section of 
the Instructions for Continued Airworthiness. This proposed AD results 
from fuel system reviews conducted by the manufacturer. We are 
proposing this AD to prevent electrical current from flowing through a 
MOV actuator into a fuel tank, which could create a potential ignition 
source inside the fuel tank. This condition, in combination with 
flammable fuel vapors, could result in a fuel tank explosion and 
consequent loss of the airplane.

DATES: We must receive comments on this proposed AD by September 22, 
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 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: Margaret Langsted, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6500; 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-2008-0847; 
Directorate Identifier 2008-NM-056-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

[[Page 45894]]

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.
    Boeing has found that, under specific conditions, it is possible 
for electrical current to flow through a motor operated valve (MOV) 
actuator into a fuel tank, which could create a potential ignition 
source inside the fuel tank. This condition, if not corrected, in 
combination with flammable fuel vapors, could result in a fuel tank 
explosion and consequent loss of the airplane.

Other Related Rulemaking

    On May 14, 2008, we issued AD 2008-11-13, amendment 39-15536 (73 FR 
30737, May 29, 2008), applicable to certain Boeing Model 777-200, -
200LR, -300, and -300ER series airplanes. That AD requires revising the 
Airworthiness Limitations (AWLs) section of the Instructions for 
Continued Airworthiness (ICA) by incorporating new limitations for fuel 
tank systems to satisfy SFAR 88 requirements. That AD also requires the 
initial performance of certain repetitive inspections specified in the 
AWLs to phase in those inspections, and repair if necessary. That AD 
resulted from a design review of the fuel tank systems. We issued that 
AD to prevent the potential for ignition sources inside fuel tanks 
caused by latent failures, alterations, repairs, or maintenance 
actions, which, in combination with flammable fuel vapors, could result 
in fuel tank explosions and consequent loss of the airplane. 
Incorporating AWL No. 28-AWL-19 and No. 28-AWL-20 into the AWLs section 
of the ICA in accordance with paragraph (g)(2) of AD 2008-11-13, 
terminates the action required by paragraph (h) of this AD.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 777-28A0034, dated 
August 2, 2007. The service bulletin describes procedures for doing an 
inspection of the MOV actuators of the main and center fuel tanks for a 
certain part number; replacing the MOV actuator with a new MOV actuator 
if necessary; and measuring the electrical resistance of the bond from 
the adapter plate to the airplane structure, and corrective actions if 
necessary. The corrective actions include reworking the bracket, 
cleaning and refinishing the bracket area, removing and reworking the 
index plate, and electrically bonding and installing the index plate.
    We have also reviewed Section 9, Revision 28, dated February 2006, 
of Boeing 777 Maintenance Planning Data (MPD) Document, D622W001-9 
(hereafter referred to as ``Boeing 777 MPD''). Subsection E of Section 
9 of the Boeing 777 MPD adds new AWLs No. 28-AWL-19 and No. 28-AWL-20, 
which are critical design configuration control limitations (CDCCLs) to 
address inspection and repair of the MOV actuators.

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 actions 
specified in the service information described previously.

Costs of Compliance

    We estimate that this proposed AD would affect 197 airplanes of 
U.S. registry. We also estimate that it would take about 352 or 452 
work-hours per product to comply with this proposed AD, depending on 
the product configuration. The average labor rate is $80 per work-hour. 
Based on these figures, we estimate the cost of this proposed AD to the 
U.S. operators to be $5,547,520 to $7,123,520, or $28,160 to $36,160 
per product, depending on the product configuration.

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-2008-0847; Directorate Identifier 2008-NM-
056-AD.

Comments Due Date

    (a) We must receive comments by September 22, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 777-200, -200LR, -300, and -
300ER series airplanes, certificated in any category; as identified 
in Boeing Alert Service Bulletin 777-28A0034, dated August 2, 2007.

    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

[[Page 45895]]

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 (k) 
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.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent electrical current 
from flowing through a motor operated valve (MOV) actuator into a 
fuel tank, which could create a potential ignition source inside the 
fuel tank. This condition, in combination with flammable fuel 
vapors, could result in a fuel tank explosion and consequent loss of 
the airplane.

Compliance

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

Inspection

    (f) Within 60 months after the effective date of this AD, do an 
inspection of the MOV actuators of the main and center fuel tanks 
for part number MA20A1001-1, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 777-28A0034, dated 
August 2, 2007.

Replacement

    (g) If any part number MA20A1001-1 is found during the 
inspection required by paragraph (f) of this AD, within 60 months 
after the effective date of this AD, do the actions specified in 
paragraphs (g)(1) and (g)(2) of this AD by accomplishing all the 
applicable actions specified in the Accomplishment Instructions of 
Boeing Alert Service Bulletin 777-28A0034, dated August 2, 2007. Do 
all applicable corrective actions before further flight.
    (1) Replace the MOV actuator with a new MOV actuator, part 
number MA030A1001.
    (2) Measure the electrical resistance of the bond from the 
adapter plate to the airplane structure, and do all applicable 
corrective actions.

Airworthiness Limitations (AWLs): Revision for AWL No. 28-AWL-19 and 
28-AWL-20

    (h) Concurrently with accomplishing the actions required by 
paragraph (g) of this AD, revise the AWLs section of the 
Instructions for Continued Airworthiness (ICA) by incorporating AWL 
No. 28-AWL-19 and No. 28-AWL-20 of Subsection E of Section 9, 
Revision 28, dated February 2006, of the Boeing 777 Maintenance 
Planning Data (MPD) Document, D622W001-9.

No Alternative Critical Design Configuration Control Limitations 
(CDCCLs)

    (i) After accomplishing the action specified in paragraph (h) of 
this AD, no alternative CDCCLs may be used unless the CDCCLs are 
approved as an AMOC in accordance with the procedures specified in 
paragraph (k) of this AD.

Terminating Action for AWLs Revision

    (j) Incorporating AWL No. 28-AWL-19 and No. 28-AWL-20 into the 
AWLs section of the ICA in accordance with paragraph (g)(2) of AD 
2008-11-13, amendment 39-15536, terminates the action required by 
paragraph (h) of this AD.

Alternative Methods of Compliance (AMOCs)

    (k)(1) The Manager, Seattle ACO, FAA, ATTN: Margaret Langsted, 
Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, SACO, 1601 
Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6500; 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 July 29, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-18211 Filed 8-6-08; 8:45 am]

BILLING CODE 4910-13-P
