[Federal Register Volume 72, Number 117 (Tuesday, June 19, 2007)]
[Proposed Rules]
[Pages 33701-33703]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-11781]



[[Page 33701]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-28375; Directorate Identifier 2007-NM-015-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767-200 and 767-300 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 certain Boeing Model 767-200 and 767-300 series airplanes. This 
proposed AD would require reworking certain duct assemblies in the 
environmental control system (ECS). This proposed AD results from 
reports of duct assemblies in the ECS with burned Boeing Material 
Specification (BMS) 8-39 polyurethane foam insulation. This proposed AD 
also results from a report from the airplane manufacturer that 
airplanes were assembled with duct assemblies in the ECS wrapped with 
BMS 8-39 polyurethane foam insulation, which is a material for which 
the fire retardant properties deteriorate with age. We are proposing 
this AD to prevent a potential electrical arc from igniting the BMS 8-
39 polyurethane foam insulation on the duct assemblies of the ECS, 
which could propagate a small fire and lead to a larger fire that might 
spread throughout the airplane through the ECS.

DATES: We must receive comments on this proposed AD by August 3, 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, P.O. Box 3707, Seattle, 
Washington 98124-2207, for the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Patrick Gillespie, Aerospace Engineer, 
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; telephone (425) 917-6429; fax (425) 917-6590.

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-2007-
28375; Directorate Identifier 2007-NM-015-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

    We have received reports of duct assemblies in the environmental 
control system (ECS) with burned Boeing Material Specification (BMS) 8-
39 polyurethane foam insulation on two Boeing Model 767-200 series 
airplanes. The airplane manufacturer has also notified us that certain 
Boeing Model 767-200 and 767-300 series airplanes were assembled with 
duct assemblies in the ECS wrapped with BMS 8-39 polyurethane foam 
insulation. The fire-retardant properties of the BMS 8-39 polyurethane 
foam insulation deteriorate with age. This, along with dust, dirt, and 
other carbon particulate contamination of the insulation on the ducts, 
adds an available fuel source for a potential fire. Once ignited, the 
foam insulation emits noxious smoke, does not self-extinguish, and 
drips droplets of liquefied polyurethane, which can further propagate a 
fire. Because the insulation is wrapped around the duct assemblies, 
which are located throughout the airplane, if the insulation is ignited 
a fire could potentially travel along the ducts and spread throughout 
the airplane. This condition, if not corrected, could result in a 
potential electrical arc igniting the BMS 8-39 polyurethane foam 
insulation on the duct assemblies of the ECS, which could propagate a 
small fire and lead to a larger fire that might spread throughout the 
airplane through the ECS.

Other Relevant Rulemaking

    We are considering additional rulemaking for Boeing Model 737-100, 
-200, -200C, and -300 series airplanes that have been determined to be 
subject to the same unsafe condition.
    Additionally, on December 14, 2001, we issued AD 2001-26-09, 
amendment 39-12573 (66 FR 66734, December 27, 2001), applicable to 
certain Boeing Model 767-200 series airplanes. That AD requires a one-
time inspection for damage of the water line heater tape where it 
passes close to the duct assemblies of the air distribution system for 
the flight compartment. That AD also requires eventual replacement of 
certain duct assemblies or foam insulation on those duct assemblies 
with new assemblies or improved foam insulation. That AD was prompted 
by a report of burned BMS 8-39 polyurethane foam insulation on an air 
distribution system duct located in the electronics and electrical (E/
E) compartment. The actions required by that AD are intended to prevent 
ignition of foam insulation on the air distribution ducts, which could 
result in a fire in the airplane.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 767-21A0167, Revision 1, 
dated December 19, 2006. The service

[[Page 33702]]

bulletin describes procedures for reworking the affected duct 
assemblies in the air distribution system (sections 41, 45, and 46), 
the Gasper air system (sections 41, 43, 45, and 46), the forward E/E 
compartment air supply, and the instrument panel cooling supply. The 
rework includes removing the BMS 8-39 polyurethane foam insulation and 
replacing it with BMS 8-300 polyimide foam insulation that meets 
flammability criteria of Section 25.856 (``Fire Protection: Thermal/
Acoustic Insulation Materials'') of the Federal Aviation Regulations 
(14 CFR 25.856(a)). The service bulletin also describes procedures for 
part-marking the duct assemblies with new part numbers once the rework 
has been accomplished. 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 
``Difference Between the Proposed AD and the Service Bulletin.''

Difference Between the Proposed AD and the Service Bulletin

    Boeing Service Bulletin 767-21A0167, Revision 1, dated December 19, 
2006, recommends accomplishing the duct assembly rework ``during the 
next heavy maintenance visit, not to exceed 24,000 flight-hours from 
the date on this service bulletin.'' This proposed AD would require 
operators to accomplish the rework within 72 months after the effective 
date of this AD. In developing the compliance time for this action, we 
considered the degree of urgency associated with addressing the subject 
unsafe condition, the availability of required parts and the practical 
aspect of reworking the duct assemblies within an interval of time that 
parallels normal scheduled maintenance for most affected operators, and 
the manufacturer's recommendations. We have determined that 72 months 
represents an appropriate interval of time in which to modify the 
affected fleet without adversely affecting the safety of these 
airplanes. Based on the average Model 767 fleet utilization rate of 
approximately 4,000 flight hours per year, we have determined that the 
proposed compliance time of 72 months is equivalent to the 
manufacturer's recommended compliance time of 24,000 flight hours. We 
have coordinated this difference with Boeing.

Costs of Compliance

    There are about 130 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

                                                                     Estimated Costs
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                                                                                                                        Number of U.S.-
                 Action                          Work hours           Average labor    Parts cost per    Average cost      registered     Average fleet
                                                                      rate per hour       airplane       per airplane      airplanes           cost
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Duct assembly rework...................  7, per duct (average 50                $80           $4,955          $32,955               96       $3,163,680
                                          ducts per airplane).
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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):

Boeing: Docket No. FAA-2007-28375; Directorate Identifier 2007-NM-
015-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by August 3, 
2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Model 767-200 and 767-300 series 
airplanes, certificated in any category; as identified in Boeing 
Service

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Bulletin 767-21A0167, Revision 1, dated December 19, 2006.

Unsafe Condition

    (d) This AD results from reports of duct assemblies in the 
environmental control system (ECS) with burned Boeing Material 
Specification (BMS) 8-39 polyurethane foam insulation. This AD also 
results from a report from the airplane manufacturer that airplanes 
were assembled with duct assemblies in the ECS wrapped with BMS 8-39 
polyurethane foam insulation, a material of which the fire retardant 
properties deteriorate with age. We are issuing this AD to prevent a 
potential electrical arc from igniting the BMS 8-39 polyurethane 
foam insulation on the duct assemblies or the ECS, which could 
propagate a small fire and lead to a larger fire that might spread 
throughout the airplane through the ECS.

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.

ECS Duct Assembly Rework

    (f) Except as provided by paragraph (g) of this AD, within 72 
months after the effective date of this AD, rework the duct 
assemblies in the ECS for the air distribution system at sections 
41, 45, and 46; the Gasper air system at sections 41, 43, 45, and 
46; the forward electronic and electrical (E/E) compartment air 
supply; and the instrument panel cooling supply; in accordance with 
the Accomplishment Instructions and Appendices A and B of Boeing 
Service Bulletin 767-21A0167, Revision 1, dated December 19, 2006.

Optional Part Installed

    (g) If an affected duct assembly having a part number other than 
part number 217T2109-12, or a part number other than any part number 
specified in the applicable figure of Boeing Service Bulletin 767-
21A0167, Revision 1, dated December 19, 2006, is found installed, 
and that part number is listed as an optional part number in the 
table in paragraph B.2., ``Optional Part Table,'' of the 
Accomplishment Instructions of the service bulletin: No rework is 
required for that duct assembly only.

Parts Installation

    (h) As of the effective date of this AD, no person may install 
an air distribution system, Gasper air system, forward E/E 
compartment air supply, or instrument panel cooling supply duct 
assembly with BMS 8-39 polyurethane foam insulation on any airplane.

Alternative Methods of Compliance (AMOCs)

    (i)(1) The Manager, Seattle 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 June 8, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-11781 Filed 6-18-07; 8:45 am]
BILLING CODE 4910-13-P