[Federal Register Volume 75, Number 14 (Friday, January 22, 2010)]
[Proposed Rules]
[Pages 3662-3664]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-1176]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0046; Directorate Identifier 2009-NM-086-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Model 737-300, -400, 
-500, -600, -700, and -800 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Model 737-300, -400, -500, -600, -700, and -800 series 
airplanes. This proposed AD would require inspecting to verify the part 
number of the low-pressure flex-hoses of the crew oxygen system 
installed under the oxygen mask stowage boxes located within the flight 
deck, and replacing the flex-hose with a new non-conductive low-
pressure flex-hose if necessary. This proposed AD results from reports 
of low-pressure flex-hoses of the crew oxygen system that burned 
through due to inadvertent electrical current from a short circuit in 
the audio select panel. We are proposing this AD to prevent inadvertent 
electrical current, which can cause the low-pressure flex-hoses of the 
crew oxygen system to melt or burn, causing oxygen system leakage and 
smoke or fire.

DATES: We must receive comments on this proposed AD by March 8, 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 [email protected]; 
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 or 
425-227-1152.

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: Robert Hettman, Aerospace Engineer, 
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle 
ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6457; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about

[[Page 3663]]

this proposed AD. Send your comments to an address listed under the 
ADDRESSES section. Include ``Docket No. FAA-2010-0046; Directorate 
Identifier 2009-NM-086-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 low-pressure flex-hoses of the crew 
oxygen system that burned through due to inadvertent electrical current 
from a short circuit in the audio select panel on a Model 757 airplane. 
An electrical current went through the support structure to the flight 
crew mask stowage box and through the low-pressure oxygen hose. This 
caused the spring inside the low-pressure oxygen hose to act as an 
electrical conductor and heat up, causing the hose to burn through. 
This condition, if not corrected, could result in the low-pressure 
flex-hose of the crew oxygen system to melt or burn, causing oxygen 
system leakage and smoke or fire.

Relevant Service Information

    We have reviewed Boeing Service Bulletin 737-35A1053, Revision 1, 
dated June 1, 2000; and Boeing Service Bulletin 737-35A1058, Revision 
1, dated June 1, 2000. The service bulletins describe procedures for 
replacing the existing low-pressure flex-hoses of the crew oxygen 
system installed under the oxygen mask stowage boxes in the flight deck 
with new non-conductive low-pressure flex-hoses of the oxygen system.

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 these same type 
designs. 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

    Although Boeing Service Bulletins 737-35A1053, Revision 1; and 737-
35A1058, Revision 1; both dated June 1, 2000; recommend accomplishing 
the replacement ``at the earliest opportunity when manpower, material 
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 
proposed 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 36 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 Boeing.

Other Rulemaking

    The oxygen mask installations on certain Boeing Company Model 747, 
757, and 767 airplanes are almost identical to those on the affected 
Model 737 airplanes. Therefore, all of these airplanes may be subject 
to the identified unsafe condition. We are considering similar 
rulemaking related to the identified unsafe condition for certain Model 
747, 757, and 767 airplanes.

Costs of Compliance

    We estimate that this proposed AD would affect 851 airplanes of 
U.S. registry. We also estimate that it would take about 1 work-hour 
per product to comply with this proposed AD. The average labor rate is 
$80 per work-hour. Based on these figures, we estimate the cost of this 
proposed AD to the U.S. operators to be $68,080, or $80 per product.

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-2010-0046; Directorate Identifier 
2009-NM-086-AD.

Comments Due Date

    (a) We must receive comments by March 8, 2010.

Affected ADs

    (b) None.

[[Page 3664]]

Applicability

    (c) This AD applies to the airplanes identified in paragraphs 
(c)(1) and (c)(2) of this AD, certificated in any category.
    (1) The Boeing Company Model 737-300, -400, and -500 series 
airplanes, as identified in Boeing Service Bulletin 737-35A1053, 
Revision 1, dated June 1, 2000.
    (2) The Boeing Company Model 737-600, -700, and -800 series 
airplanes, as identified in Boeing Service Bulletin 737-35A1058, 
Revision 1, dated June 1, 2000.

Subject

    (d) Air Transport Association (ATA) of America Code 35: Oxygen.

Unsafe Condition

    (e) This AD results from reports of low-pressure flex-hoses of 
the crew oxygen system that burned through due to inadvertent 
electrical current from a short circuit in the audio select panel. 
The Federal Aviation Administration is issuing this AD to prevent 
inadvertent electrical current, which can cause the low-pressure 
flex-hoses of the crew oxygen system to melt or burn, resulting in 
oxygen system leakage and smoke or fire.

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.

Inspection and Replacement

    (g) Within 36 months after the effective date of this AD, do an 
inspection to determine whether any low-pressure flex-hose of the 
crew oxygen system installed under the oxygen mask stowage box in 
the flight deck has a part number identified in Table 1 of this AD. 
A review of airplane maintenance records is acceptable in lieu of 
this inspection if the part number of the low-pressure flex-hoses of 
the crew oxygen system can be conclusively determined from that 
review.
    (1) For any hose having a part number identified in Table 1 of 
this AD, before further flight, replace the hose with a new or 
serviceable part, in accordance with the Accomplishment Instructions 
of Boeing Service Bulletin 737-35A1053, Revision 1, dated June 1, 
2000; or Boeing Service Bulletin 737-35A1058, Revision 1, dated June 
1, 2000; as applicable.
    (2) For any hose not having a part number identified in Table 1 
of this AD no further action is required by this paragraph.

                    Table 1--Applicable Part Numbers
------------------------------------------------------------------------
                                       Equivalent Boeing supplier part
                                                   numbers
 Boeing specification part number  -------------------------------------
                                       Puritan Bennett       Hydraflow
------------------------------------------------------------------------
10-60174-31.......................  173470-31...........        37001-31
10-60174-35.......................  173470-35...........        37001-35
10-60174-46.......................  Not Applicable......        37001-46
60B50059-99.......................  Not Applicable......        38001-99
60B50059-124......................  Not Applicable......       38001-124
------------------------------------------------------------------------

Parts Installation

    (h) As of the effective date of this AD, no person may install a 
crew oxygen hose with a part number identified in Table 1 of this 
AD, on any airplane.

Actions Accomplished According to Previous Issue of Service Bulletin

    (i) Actions accomplished before the effective date of this AD in 
accordance with Boeing Alert Service Bulletin 737-35A1053, dated 
September 2, 1999; or Boeing Alert Service Bulletin 737-35A1058, 
dated September 2, 1999; as applicable; are considered acceptable 
for compliance with the corresponding actions specified in this AD.

Alternative Methods of Compliance (AMOCs)

    (j)(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: Robert Hettman, Aerospace Engineer, Cabin Safety and 
Environmental Systems Branch, ANM-150S, FAA, Seattle ACO, 1601 Lind 
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-
6457; fax (425) 917-6590. Or, e-mail information to [email protected].
    (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 January 8, 2010.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2010-1176 Filed 1-21-10; 8:45 am]
BILLING CODE 4910-13-P