[Federal Register Volume 71, Number 59 (Tuesday, March 28, 2006)]
[Proposed Rules]
[Pages 15351-15354]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-4443]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24256; Directorate Identifier 2006-NM-010-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model 717-200 
Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain McDonnell Douglas Model 717-200 airplanes. This proposed AD 
would require replacing the lightning critical clamp bases of the fuel 
tank vent system with improved clamp bases; and checking the electrical 
bond of the modified self-bonding mounting clamps. This proposed AD 
results from an investigation that revealed the aluminum foil strip on 
the nylon base of the ground clamps can fracture or separate from the 
base. We are proposing this AD to ensure that the fuel pipes are 
properly bonded to the airplane structure. Improper bonding could 
prevent electrical energy from a lightning strike from dissipating to 
the airplane structure, which could result in a fuel tank explosion.

[[Page 15352]]


DATES: We must receive comments on this proposed AD by May 12, 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-
24256; Directorate Identifier 2006-NM-010-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 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 another 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 bonds of 
in-tank fuel system components were degrading on McDonnell Douglas DC-9 
and MD-80 airplanes. Investigation revealed that the aluminum foil 
strip on the nylon base of the ground clamps can fracture or separate 
from the base. These grounded clamp bases are used to bond the fuel 
pipe to the airplane structure in the wing leading edge, main fuel 
tanks, center fuel tank, and aft fuselage on Model 717-200 airplanes. 
Bonding of the fuel pipes to the airplane structure is critical to 
ensure that electrical energy from a lightning strike dissipates to the 
airplane structure. This condition, if not corrected, could result in a 
fuel tank explosion.
    The grounded clamp bases on certain Model 717-200 airplanes are 
identical to those on the affected Model DC-9 and MD-80 airplanes. 
Therefore, all of these models may be subject to the same unsafe 
condition.

Other Related Rulemaking

    Boeing has issued Service Bulletin DC9-28-211, dated February 23, 
2005, to address replacing the clamp bases for the fuel vent pipe with 
improved clamp bases on all McDonnell Douglas Model DC-9-10, -20, -30, 
-40, and -50 series airplanes; we are planning to address the unsafe 
condition of that service bulletin with a separate rulemaking action.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 717-28-0004, Revision 2, 
dated March 11, 2005. The service bulletin describes procedures for 
replacing the grounded clamp bases for the fuel pipes located in the 
wing leading edge, main fuel tanks, center fuel tank, and aft fuselage 
with improved clamp bases; and checking the electrical bond of the 
modified self-bonding mounting

[[Page 15353]]

clamps. Accomplishing the actions specified in the service information 
is intended to adequately address the unsafe condition.
    The service bulletin refers to Chapter 28-00-00 of Boeing 717 
Aircraft Maintenance Manual and Chapter 20-50-01, Class ``L,'' of the 
Boeing 717 Standard Wiring Practices Manual as additional sources of 
service information for checking the electrical bond of the modified 
self-bonding clamps.

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 NPRM and Service Bulletin.''

Differences Between the NPRM and Service Bulletin

    The service bulletin describes procedures for replacing 43 grounded 
clamp bases with improved clamp bases, as identified in Tables 1 and 2 
of the Accomplishment Instructions. This NPRM, however, proposes to 
require replacing only the lightning critical clamp bases identified in 
Table 1. We have determined that replacement of the lightning critical 
clamp bases adequately addresses the unsafe condition identified in 
this NPRM.
    The service bulletin specifies checking the electrical bond of the 
modified self-bonding mounting clamps, but does not specify what 
corrective action to take if an electrical bond fails that check. This 
NPRM proposes to require, before further flight, repairing any 
electrical bond of the mounting clamp according to a method approved by 
the Manager, Los Angeles Aircraft Certification Office, FAA. Chapter 
28-00-00 of Boeing 717 Aircraft Maintenance Manual and Chapter 20-50-01 
of the Boeing 717 Standard Wiring Practices Manual are one approved 
method for repairing an electrical bond.
    Although the service bulletin recommends accomplishing the 
replacements ``at a scheduled maintenance period when manpower, 
materials, and facilities are available,'' we have determined that this 
imprecise compliance time would not address the identified unsafe 
condition in a timely manner. In developing an appropriate compliance 
time for this AD, we considered not only the manufacturer's 
recommendation, but the degree of urgency associated with addressing 
the subject unsafe condition, the average utilization of the affected 
fleet, and the time necessary to perform the modifications. In light of 
all of these factors, we find a compliance time of 78 months for 
completing the required actions to be warranted, in that it represents 
an appropriate interval of time for affected airplanes to continue to 
operate without compromising safety. This difference has been 
coordinated with the airplane manufacturer.

Costs of Compliance

    There are about 120 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 92 airplanes of 
U.S. registry. The proposed actions would take about 16 work hours per 
airplane, at an average labor rate of $80 per work hour. Required parts 
would cost about $239 per airplane. Based on these figures, the 
estimated cost of the proposed AD for U.S. operators is $139,748, or 
$1,519 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-2006-24256; Directorate Identifier 
2006-NM-010-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 12, 
1006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to McDonnell Douglas Model 717-200 
airplanes, certificated in any category; as identified in Boeing 
Service Bulletin 717-28-0004, Revision 2, dated March 11, 2005.

Unsafe Condition

    (d) This AD results from an investigation that revealed the 
aluminum foil strip on the nylon base of the ground clamps can 
fracture or separate from the base. We are issuing this AD to ensure 
that the fuel pipes are properly bonded to the airplane structure. 
Improper bonding could prevent electrical energy from a lightning 
strike from dissipating to the airplane structure, which could 
result in a fuel tank explosion.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within

[[Page 15354]]

the compliance times specified, unless the actions have already been 
done.

Replace the Grounded Clamp Bases

    (f) Within 78 months after the effective date of this AD, 
replace the lightning critical clamp bases of the fuel tank vent 
system with improved clamp bases, in accordance with Table 1 of 
Figure 1 of the Accomplishment Instructions of Boeing Service 
Bulletin 717-28-0004, Revision 2, dated March 11, 2005. Before 
further flight after the replacement, check the electrical bond of 
the modified self-bonding mounting clamps in accordance with the 
service bulletin. If any electrical bond fails the check, before 
further flight, repair the electrical bond of the mounting clamp 
according to a method approved by the Manager, Los Angeles Aircraft 
Certification Office (ACO), FAA. Chapter 28-00-00 of the Boeing 717 
Aircraft Maintenance Manual and Chapter 20-50-01 of the Boeing 717 
Standard Wiring Practices Manual are one approved method.

Alternative Methods of Compliance (AMOCs)

    (g)(1) The Manager, Los Angeles 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 20, 2006.

Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E6-4443 Filed 3-27-06; 8:45 am]
BILLING CODE 4910-13-P