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[Federal Register: April 12, 2010 (Volume 75, Number 69)]
[Proposed Rules]               
[Page 18446-18449]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr12ap10-16]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0275; Directorate Identifier 2009-NM-231-AD]
RIN 2120-AA64

 
Airworthiness Directives; The Boeing Company Model 747-100, 747-
100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 
747-400F, 747SR, and 747SP Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-
200F, 747-300, 747-400, 747-400F, 747SR, and 747SP series airplanes. 
This proposed AD would require reworking or replacing 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, a material of 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 May 27, 2010.

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 proposed AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, P. 
O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1; fax 206-766-5680; e-mail me.boecom@boeing.com; 
Internet https://www.myboeingfleet.com. You may review copies of the 
referenced service information at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue SW., Renton, Washington. For information 
on the availability of this material at the FAA, call 425-227-1221.

[[Page 18447]]

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: Sue McCormick, Aerospace Engineer, 
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; telephone (303) 342-1082; fax (425) 917-6590.

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-2010-0275; 
Directorate Identifier 2009-NM-231-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

    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 Model 767-200 series airplanes. 
The airplane manufacturer has also notified us that certain Model 767-
200 and 767-300 series airplanes and certain Model 747 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 may spread 
throughout the airplane through the ECS.

Other Relevant Rulemaking

    On January 14, 2008, we issued AD 2008-02-16, amendment 39-15346, 
applicable to certain Model 767-200 and 767-300 series airplanes. That 
AD requires reworking certain duct assemblies in the ECS. That AD 
resulted from reports of duct assemblies in the ECS with burned BMS 8-
39 polyurethane foam insulation. That AD also resulted 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 issued that 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.
    Additionally, on December 14, 2001, we issued AD 2001-26-09, 
amendment 39-12573 (66 FR 66734, December 27, 2001), applicable to 
certain 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 
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.
    We are considering additional rulemaking for Model 737-100, -200, -
200C, and -300 series airplanes, which have been determined to be 
subject to the same unsafe condition.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 747-21A2421, Revision 2, 
dated December 19, 2006. This service bulletin describes procedures for 
reworking the affected duct assemblies in approximately 44 locations 
within the ECS systems. The affected duct assemblies vary depending on 
airplane configuration. These are some examples of affected ECS 
systems:
     Air conditioning, flight deck
     Duct installation, conditioned air
     Duct installation, air distribution system
     Duct installation, individual air system
     Anemostat installation, air distribution system
     Humidifier duct installation
     Heat exchanger installation, air conditioning system
     Recirculation fan installation, flight deck
    We have also reviewed Boeing Service Bulletin 747-21A2422, Revision 
2, dated November 16, 2006. This service bulletin describes procedures 
for reworking or replacing the single duct assembly in the forward 
lower cargo bay. 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)).
    These service bulletins also describe procedures for part-marking 
reworked duct assemblies with new part numbers.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design. 
This proposed AD would require accomplishing the actions specified in 
the service information described previously, except as discussed under 
``Differences Between the Proposed AD and the Service Bulletins.''

Differences Between the Proposed AD and the Service Bulletins

    Boeing Service Bulletin 747-21A2421, Revision 2, dated December 19, 
2006, recommends reworking the affected duct assemblies ``during the 
next heavy maintenance visit, not to

[[Page 18448]]

exceed 30,000 flight-hours'' from the date on that service bulletin. 
Boeing Service Bulletin 747-21A2422, Revision 2, dated November 16, 
2006, does not recommend any compliance time for reworking or replacing 
the affected duct assemblies. This proposed AD would require operators 
to rework or replace the affected duct assemblies within 72 months 
after the effective date of the AD. In developing the compliance time 
for this action, we considered the degree of urgency associated with 
addressing the subject unsafe condition. We also considered the 
availability of required parts and the practical aspect of reworking or 
replacing the affected duct assemblies within an interval that 
parallels normal scheduled maintenance for most affected operators. We 
have determined that the average utilization of the Model 747 fleet is 
approximately 5,000 flight hours each year. Therefore, we have 
determined that 72 months is equivalent to the recommended compliance 
time of 30,000 flight hours and it represents an appropriate interval 
in which an ample number of required parts will be available to modify 
the affected fleet without adversely affecting the safety of these 
airplanes. This difference has been coordinated with Boeing.

Costs of Compliance

    There are about 558 airplanes of the affected design in the 
worldwide fleet. The average labor rate is $85 per work-hour. The 
following table provides the estimated costs for U.S. operators to 
comply with this proposed AD.

                                                                     Estimated Costs
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                                                                 Parts cost, per                               Number of U.S.-
               Action                      Work hours               airplane           Cost per airplane     registered airplanes        Fleet cost
--------------------------------------------------------------------------------------------------------------------------------------------------------
Duct assembly rework, specified in   8 per duct (average of  $12,305 (average).....  $100,705 (average)...  185..................  $18,630,425.
 Boeing Service Bulletin              130 ducts per
 747[dash]21A2421.                    airplane).
Duct assembly rework or              1 per duct (1 duct per  The manufacturer        $85..................  Up to 168............  Up to $14,280.
 replacement, specified in Boeing     airplane).              states that it will
 Service Bulletin 747[dash]21A2422.                           supply required parts
                                                              to the operators at
                                                              no cost..
--------------------------------------------------------------------------------------------------------------------------------------------------------

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 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 this 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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, 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 FAA amends Sec.  39.13 by adding the following new AD:

The Boeing Company: Docket No. FAA-2010-0275; Directorate Identifier 
2009-NM-231-AD.

Comments Due Date

    (a) We must receive comments by May 27, 2010.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to the airplanes specified in paragraphs 
(c)(1) and (c)(2) of this AD, certificated in any category.
    (1) The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 
747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP 
series airplanes identified in Boeing Service Bulletin 747-21A2421, 
Revision 2, dated December 19, 2006.
    (2) The Boeing Company Model 747-100, 747-100B, 747-200B, 747-
200C, 747-200F, 747-300, 747-400F, 747SR, and 747SP series airplanes 
identified in Boeing Service Bulletin 747-21A2422, Revision 2, dated 
November 16, 2006.

Subject

    (d) Air Transport Association (ATA) of America Code 21: Air 
conditioning.

Unsafe Condition

    (e) 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 of the ECS, which could

[[Page 18449]]

propagate a small fire and lead to a larger fire that could spread 
throughout the airplane through the ECS.

Compliance

    (f) 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 or Replacement

    (g) Within 72 months after the effective date of this AD, rework 
or replace the applicable duct assemblies in the ECS specified in 
and in accordance with the Accomplishment Instructions and 
Appendices A through F of Boeing Service Bulletin 747-21A2421, 
Revision 2, dated December 19, 2006 (for Model 747-100, 747-100B, 
747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, 
and 747SP series airplanes); and the Accomplishment Instructions and 
Appendices A through C of Boeing Service Bulletin 747-21A2422, 
Revision 2, dated November 16, 2006 (for Model 747-100, 747-100B, 
747-200B, 747-200C, 747-200F, 747-300, 747-400F, 747SR, and 747SP 
series airplanes).

Parts Installation

    (h) As of the effective date of this AD, no person may install 
an ECS 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 (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. Send information to 
ATTN: Sue McCormick, Aerospace Engineer, Cabin Safety and 
Environmental Systems Branch, ANM-150S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 
98057-3356; telephone (303) 342-1082; fax (425) 917-6590. Or, e-mail 
information to 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (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 principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.

    Issued in Renton, Washington, on April 1, 2010.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-8249 Filed 4-9-10; 8:45 am]
BILLING CODE 4910-13-P
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