FR Doc E7-3169

[Federal Register: February 26, 2007 (Volume 72, Number 37)]
[Proposed Rules]
[Page 8311-8313]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26fe07-29]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-27341; Directorate Identifier 2006-NM-272-AD]
RIN 2120-AA64

Airworthiness Directives; McDonnell Douglas Model MD-11 and MD-
11F 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 all McDonnell Douglas Model MD-11 and MD-11F airplanes. This
proposed AD would require installing bracket assemblies and jumper
wires in the center main wheel well to improve the bonding path between
the structure (wall) of the lower auxiliary fuel tank and its internal
fuel pumps; measuring the electrical resistance between the fuel pump
housings and the fuel tank structure; and doing corrective actions if
necessary. This proposed AD results from fuel system reviews conducted
by the manufacturer. We are proposing this AD to detect and correct an
inadequate bond between the internal fuel pump housings and the
structure of the lower auxiliary fuel tank. This condition, if not
corrected, could fail to meet fault current requirements and result in
a potential ignition source that, in combination with flammable fuel
vapors, could cause a fuel tank explosion and consequent loss of the
airplane.

[[Page 8312]]

DATES: We must receive comments on this proposed AD by April 12, 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: Docket Management Facility, U.S. Department of
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401,
Washington, DC 20590.
Fax: (202) 493-2251.
Hand Delivery: Room PL-401 on the plaza level of the
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
Contact Boeing Commercial Airplanes, Long Beach Division, 3855
Lakewood Boulevard, Long Beach, California 90846, Attention: Data and
Service Management, Dept. C1-L5A (D800-0024), for the service
information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT: Samuel Lee, Aerospace Engineer,
Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification
Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137;
telephone (562) 627-5262; fax (562) 627-5210.

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 ``Docket No.
FAA-2007-27341; Directorate Identifier 2006-NM-272-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 Management Facility office

between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT
street address stated in the ADDRESSES section. Comments will be
available in the AD docket shortly after the Docket Management System
receives them.

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.
We have received a report indicating that the electrical bond may
not be adequate between the internal fuel pumps of the lower auxiliary
fuel tank and the fuel tank structure (wall), on Model MD-11 and MD-11F
airplanes. This condition, if not corrected, could fail to meet fault
current requirements and result in a potential ignition source that, in
combination with flammable fuel vapors, could cause a fuel tank
explosion and consequent loss of the airplane.

Related Rulemaking

Operators should note that the same unsafe condition exists in
certain McDonnell Douglas Model DC-10 airplanes and that we may issue a
separate rulemaking to address those airplanes.

Relevant Service Information

We have reviewed Boeing Service Bulletin MD11-28-127, dated
September 19, 2006. The service bulletin describes procedures for
installing bracket assemblies and jumper wires between the lower
auxiliary fuel tank and its internal fuel pumps; for doing an
electrical resistance measurement between the fuel pump housings and
the auxiliary fuel tank wall; and for doing corrective actions if
necessary. Corrective actions, if any resistance measurement exceeds
2.5 milliohms, include reworking the electrical bonding between the
fuel pump housings and the fuel tank wall. 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

[[Page 8313]]

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.

Costs of Compliance

There are about 195 airplanes of the affected design in the
worldwide fleet. This proposed AD would affect about 107 airplanes of
U.S. registry. The following table provides the estimated costs for
U.S. operators to comply with this proposed AD, at an average labor
rate of $80 per work hour.

Estimated Costs
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Work Cost per
Action hours Parts airplane Fleet cost
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Install bracket assemblies and jumper wires. 4 $1,928......................... $2,248 $240,536
Do electrical resistance measurement........ 1 None required.................. 80 8,560
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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:

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):

McDonnell Douglas: Docket No. FAA-2007-27341; Directorate Identifier
2006-NM-272-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by April 12,
2007.

Affected ADs

(b) None.

Applicability

Unsafe Condition

(d) This AD results from fuel system reviews conducted by the
manufacturer. We are issuing this AD to detect and correct an
inadequate bond between the internal fuel pump housings and the
structure (wall) of the lower auxiliary fuel tank. This condition,
if not corrected, could fail to meet fault current requirements and
result in a potential ignition source that, in combination with
flammable fuel vapors, could cause a fuel tank explosion and
consequent loss of the airplane.

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.

Installation of Brackets and Jumpers, and Resistance Measurement

(f) Within 60 months after the effective date of this AD, do the
actions described in paragraphs (f)(1) and (f)(2) of this AD, in
accordance with the Accomplishment Instructions of Boeing Service
Bulletin MD11-28-127, dated September 19, 2006.
(1) Install bracket assemblies and jumper wires between the
structure of the lower auxiliary fuel tank and its internal fuel
pumps.
(2) Do an electrical resistance measurement between the fuel
pump housings and the lower auxiliary fuel tank wall.

Corrective Action

(g) If any resistance measurement done in accordance with
paragraph (f)(2) of this AD is greater than 2.5 milliohms on either
fuel pump housing: Before further flight, rework the electrical
bonding between the fuel pump housings and the lower auxiliary fuel
tank wall as needed to achieve a resistance measurement of 2.5
milliohms or less on both fuel pump housings, as described in Boeing
Service Bulletin MD11-28-127, dated September 19, 2006.

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Los Angeles 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) Before using any AMOC approved in accordance with Sec.
39.19 on any airplane to which the AMOC applies, notify the
appropriate principal inspector in the FAA Flight Standards
Certificate Holding District Office.

Issued in Renton, Washington, on February 16, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-3169 Filed 2-23-07; 8:45 am]

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