

[Federal Register: October 23, 2007 (Volume 72, Number 204)]
[Proposed Rules]               
[Page 59969-59971]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr23oc07-12]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0074; Directorate Identifier 2007-NM-151-AD]
RIN 2120-AA64

 
Airworthiness Directives; McDonnell Douglas Model MD-90-30 
Airplanes

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

[[Page 59970]]


ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain McDonnell Douglas Model MD-90-30 airplanes. This proposed 
AD would require replacement of the wire harness of the auxiliary 
hydraulic pump with a new wire harness, and routing the new wire 
harness outside of the tire burst area. This proposed AD results from 
fuel system reviews conducted by the manufacturer, as well as reports 
of shorted wires in the right wheel well and evidence of arcing on the 
power cables of the auxiliary hydraulic pump. We are proposing this AD 
to prevent shorted wires or electrical arcing at the auxiliary 
hydraulic pump, which could result in a fire in the wheel well. We are 
also proposing this AD to reduce the potential of an ignition source 
adjacent to the fuel tanks, which, 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 December 7, 
2007.

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, Long Beach Division, 3855 Lakewood Boulevard, 
Long Beach, California 90846, Attention: Data and Service Management, 
Dept. C1-L5A (D800-0024).

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: Cheyenne Del Carmen, Aerospace 
Engineer, Cabin Safety/Mechanical and Environmental Systems Branch, 
ANM-150L, FAA, Los Angeles Aircraft Certification Office, 3960 
Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 
627-5338; fax (562) 627-5210.

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-2007-0074; 
Directorate Identifier 2007-NM-151-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.
    We have received three reports indicating that operators found 
shorted wires in the right wheel well and evidence of arcing on the 
power cables of the auxiliary hydraulic pump, on three McDonnell 
Douglas Model DC-9-82 (MD-82) airplanes. One incident resulted in a 
fire in the wheel well. Investigation revealed that damage to the power 
cables was caused by structural chafing. In addition, SFAR 88 analysis 
determined that extra protection is required on the wire harness of the 
auxiliary hydraulic pump where it comes in close proximity to the 
center fuel tank; Model MD-90-30 airplanes have a similar installation. 
Boeing analysis also determined that the existing wire harness of the 
auxiliary hydraulic pump for Model MD-90-30 airplanes is routed within 
the ``tire burst'' area. Installing a new and longer wire harness for 
the auxiliary hydraulic pump and routing it outside of the tire burst 
area will minimize the possibility of chafing and wire arcing damage. 
Shorted wires or electrical arcing at the auxiliary hydraulic pump, if 
not corrected, could result in a fire in the wheel well. A potential 
ignition source adjacent to the fuel tanks, if not corrected, in 
combination with flammable fuel vapors could result in a

[[Page 59971]]

fuel tank explosion and consequent loss of the airplane.
    The installation of the auxiliary hydraulic pump wire harness on 
Model DC-9-82 (MD-82) airplanes is similar to that on the affected 
Model MD-90-30 airplanes. Therefore, all of these models are subject to 
the same unsafe condition.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin MD90-29A021, dated 
May 15, 2007. The service bulletin describes procedures for replacing 
the wire harness of the auxiliary hydraulic pump with a new wire 
harness, and routing the new wire harness outside of the tire burst 
area. 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 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 110 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 16 airplanes of 
U.S. registry. The proposed actions would take about 7 work hours per 
airplane, at an average labor rate of $80 per work hour. Required parts 
would cost about $3,997 per airplane. Based on these figures, the 
estimated cost of the proposed AD for U.S. operators is $72,912, or 
$4,557 per airplane.

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-2007-0074; Directorate Identifier 
2007-NM-151-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by December 
7, 2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to McDonnell Douglas Model MD-90-30 
airplanes, certificated in any category; as identified in Boeing 
Alert Service Bulletin MD90-29A021, dated May 15, 2007.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer, as well as reports of shorted wires in the right wheel 
well and evidence of arcing on the power cables of the auxiliary 
hydraulic pump. We are issuing this AD to prevent shorted wires or 
electrical arcing at the auxiliary hydraulic pump, which could 
result in a fire in the wheel well. We are also issuing this AD to 
reduce the potential of an ignition source adjacent to the fuel 
tanks, which, in combination with flammable fuel vapors, could 
result in 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.

Replacement

    (f) Within 18 months after the effective date of this AD, 
replace the wire harness of the auxiliary hydraulic pump with a new 
wire harness and route the new wire harness outside of the tire 
burst area, in accordance with the Accomplishment Instructions of 
Boeing Alert Service Bulletin MD90-29A021, dated May 15, 2007.

Alternative Methods of Compliance (AMOCs)

    (g)(1) The Manager, Los Angeles Aircraft Certification Office, 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with 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 12, 2007.
Stephen P. Boyd,
Assistant Manager, Transport Airplane Directorate, Aircraft 
Certification Service.
[FR Doc. E7-20823 Filed 10-22-07; 8:45 am]

BILLING CODE 4910-13-P
