[Federal Register Volume 71, Number 69 (Tuesday, April 11, 2006)]
[Proposed Rules]
[Pages 18249-18251]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3441]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24368; Directorate Identifier 2005-NM-230-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model DC-9-10, -20, -
30, -40, and -50 Series 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 DC-9-10, -20, -30, -40, and -50 series 
airplanes. This proposed AD would require replacing the clamp bases for 
the fuel vent pipe with improved clamp bases. This proposed AD results 
from reports that the foil wrapping on existing plastic clamp bases has 
migrated out of position, which compromises the bonding of the fuel 
vent lines to the airplane structure. We are proposing this AD to 
ensure that the fuel vent lines are properly bonded to the airplane 
structure. Improper bonding could prevent electrical energy from a 
lightning strike from dissipating to the airplane structure, and create 
an ignition source, which could result in a fuel tank explosion.

DATES: We must receive comments on this proposed AD by May 26, 2006.

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: Serj Harutunian, Aerospace Engineer, 
Propulsion Branch, ANM-140L, FAA, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; 
telephone (562) 627-5254; 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 ``FAA-2006-
24368; Directorate Identifier 2005-NM-230-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'' 
(67 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

[[Page 18250]]

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.
    Foil-wrapped plastic clamp bases are used to bond the fuel vent 
line to the airplane structure in parts of the fuel vent system on 
McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series 
airplanes. We have received reports that the foil wrapping on existing 
plastic clamp bases has migrated out of position on several airplanes, 
which compromises the bonding of the fuel vent lines to the airplane 
structure. Bonding of the fuel vent lines to the airplane structure is 
critical to ensure that the electrical energy from a lightning strike 
dissipates to the airplane structure. This condition, if not corrected, 
could create an ignition source and result in a fuel tank explosion.

Relevant Service Information

    We have reviewed Boeing Service Bulletin DC9-28-211, dated February 
23, 2005. The service bulletin describes procedures for replacing 
existing foil-wrapped plastic clamp bases for the fuel vent line with 
improved metal clamp bases. These replacement procedures include 
verifying the electrical conductivity of the structural bracket and 
vent pipe surfaces using an ohmmeter and taking corrective action if 
necessary. If the ohmmeter reading is more than 2.5 milliohms, the 
corrective action includes prepping and applying chemical conversion 
coating to the surface of the structural bracket and/or vent pipe, as 
applicable. 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, except as discussed under 
``Differences Between the Proposed AD and Service Bulletin.''

Differences Between the Proposed AD and Service Bulletin

    Although the service bulletin recommends accomplishing the 
replacement of clamp bases for the fuel vent line within 10 years after 
the issue date of the service bulletin, we have determined that 
interval would not address the identified unsafe condition soon enough 
to ensure an adequate level of safety for the affected fleet. In 
developing an appropriate compliance time for this AD, we considered 
the manufacturer's recommendation, the degree of urgency associated 
with the subject unsafe condition, and the time necessary to do the 
replacement. In light of all of these factors, we find that a 60-month 
compliance time represents an appropriate interval of time for affected 
airplanes to continue to operate without compromising safety. This 
difference has been coordinated with Boeing, and Boeing concurs.

Costs of Compliance

    There are about 640 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 413 airplanes of 
U.S. registry. The proposed actions would take up to 4 work hours per 
airplane, at an average labor rate of $80 per work hour. Required parts 
would cost between $1,004 and $2,008 per airplane. Based on these 
figures, the estimated cost of the proposed AD for U.S. operators is 
between $546,812 and $961,464, or $1,324 and $2,328 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.

[[Page 18251]]

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-2006-24368; Directorate Identifier 
2005-NM-230-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 26, 
2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all McDonnell Douglas Model DC-9-11, DC-
9-12, DC-9-13, DC-9-14, DC-9-15, DC-9-15F, DC-9-21, DC-9-31, DC-9-
32, DC-9-32 (VC-9C), DC-9-32F, DC-9-32F (C-9A, C-9B), DC-9-33F, DC-
9-34, DC-9-34F, DC-9-41, and DC-9-51 airplanes, certificated in any 
category.

Unsafe Condition

    (d) This AD results from reports that the foil wrapping on 
existing plastic clamp bases has migrated out of position, which 
compromises the bonding of the fuel vent lines to the airplane 
structure. We are issuing this AD to ensure that the fuel vent lines 
are properly bonded to the airplane structure. Improper bonding 
could prevent electrical energy from a lightning strike from 
dissipating to the airplane structure, and create an ignition 
source, which could result in a fuel tank explosion.

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.

Clamp Base Replacement

    (f) Within 60 months after the effective date of this AD, 
replace the existing clamp bases for the fuel vent line with 
improved metal clamp bases, by doing all of the applicable actions 
in accordance with the Accomplishment Instructions of Boeing Service 
Bulletin DC9-28-211, dated February 23, 2005. Any corrective action 
that is required following the conductivity verification, which is 
included in the replacement procedures, must be done before further 
flight.

Alternative Methods of Compliance (AMOCs)

    (g)(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 March 30, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3441 Filed 4-10-06; 8:45 am]
BILLING CODE 4910-13-P