[Federal Register Volume 72, Number 243 (Wednesday, December 19, 2007)]
[Proposed Rules]
[Pages 71830-71832]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-24521]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0346; Directorate Identifier 2007-NM-202-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
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 Model 737-300, -400, and -500 series airplanes. This 
proposed AD would require an inspection to determine the manufacturer 
and manufacture date of the oxygen masks in the passenger service unit 
and the lavatory and attendant box assemblies, corrective action if 
necessary, and other specified action. This proposed AD results from a 
report that several passenger masks with broken in-line flow indicators 
were found following a mask deployment. We are proposing this AD to 
prevent the in-line flow indicators of the passenger oxygen masks from 
fracturing and separating, which could inhibit oxygen flow to the masks 
and consequently result in exposure of the passengers and cabin 
attendants to hypoxia following a depressurization event.

DATES: We must receive comments on this proposed AD by February 4, 
2008.

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 AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

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: Susan Letcher, 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) 917-6474; 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-2007-0346; 
Directorate Identifier 2007-NM-202-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 a report indicating that several passenger masks 
with broken in-line flow indicators were found following a mask 
deployment, on a Boeing Model 777-200 series airplane. Operators 
subsequently found several more broken in-line flow indicators after 
examining the oxygen mask assemblies on other Model 777 series 
airplanes and on Model 747-400 series airplanes. Investigation revealed 
that certain flow indicators are weaker and can fracture because of 
internal residual stresses caused by the flow indicator joint design 
and manufacturing processes. Fractures cause the in-line flow indicator 
to separate and consequently prevent oxygen flow to the mask during an 
emergency. This condition, if not corrected, could result in exposure 
of the passengers and cabin attendants to hypoxia following a 
depressurization event.
    The oxygen masks on certain Model 777 airplanes and Model 747-400 
series airplanes have the same flow indicators as those installed on 
certain Model 737-300, -400, and -500 series airplanes. Therefore, the 
Model 737-300, -400, and -500 series airplanes may be subject to the 
identified unsafe condition.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 737-35-
1099, dated April 9, 2007. The service bulletin describes procedures 
for doing a general visual inspection to determine the manufacturer and 
manufacture date of the oxygen masks in the passenger service unit 
(PSU) and the lavatory and attendant box assemblies. The service 
bulletin also describes procedures for doing the corrective action if 
necessary and other specified action. The corrective action includes 
repairing any B/E Aerospace oxygen mask assembly with a manufacturing 
date after January 1, 2002, and before March 1, 2006. The service 
bulletin also specifies that as an alternative to doing the repair 
(rework), the oxygen mask assembly may be replaced with a new oxygen 
mask outside the scope of the service bulletin. The other specified 
action includes doing the oxygen mask drop test.
    Boeing Special Attention Service Bulletin 737-35-1099 refers to B/E 
Aerospace Service Bulletin 174080-35-01, dated February 6, 2006; and

[[Page 71831]]

Revision 1, dated May 1, 2006; as additional sources of service 
information for repairing the oxygen mask assembly. B/E Aerospace 
Service Bulletin 174080-35-01 describes procedures for modifying the 
oxygen mask assembly by replacing the flow indicator, part number (P/N) 
118023-02, with an improved flow indicator, P/N 118023-12. B/E 
Aerospace Service Bulletin 174080-35-01 also specifies that, as an 
alternative to modifying the oxygen mask, operators may replace the 
oxygen mask with a new oxygen mask having the improved flow indicator.
    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.

Clarification Between the Proposed AD and Service Bulletin

    Although Boeing Special Attention Service Bulletin 737-35-1099 
specifies to repair the oxygen mask assembly, the intent of the service 
bulletin is to replace it with either a new or modified oxygen mask 
assembly having an improved flow indicator. Therefore, this proposed AD 
would require replacing the oxygen mask assembly with a new or modified 
oxygen mask assembly having an improved flow indicator.

Costs of Compliance

    There are about 1,956 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 646 airplanes of 
U.S. registry. The proposed actions would take about 16 work hours per 
airplane, for an average of 180 oxygen masks per airplane distributed 
in about 45 PSU/oxygen boxes, at an average labor rate of $80 per work 
hour. Required parts would cost about $6 per oxygen mask, or $1,080 per 
airplane. Based on these figures, the estimated cost of the proposed AD 
for U.S. operators is $1,524,560, or $2,360 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):

Boeing: Docket No. FAA-2007-0346; Directorate Identifier 2007-NM-
202-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by February 
4, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-300, -400, and -500 
series airplanes, certificated in any category; as identified in 
Boeing Special Attention Service Bulletin 737-35-1099, dated April 
9, 2007.

Unsafe Condition

    (d) This AD results from a report that several passenger masks 
with broken in-line flow indicators were found following a mask 
deployment. We are issuing this AD to prevent the in-line flow 
indicators of the passenger oxygen masks from fracturing and 
separating, which could inhibit oxygen flow to the masks and 
consequently result in exposure of the passengers and cabin 
attendants to hypoxia following a depressurization event.

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.

Inspection and Related Investigative/Corrective Actions if Necessary

    (f) Within 60 months after the effective date of this AD, do a 
general visual inspection to determine the manufacturer and 
manufacture date of the oxygen masks in the passenger service unit 
and the lavatory and attendant box assemblies, and do the applicable 
corrective action and other specified action, by accomplishing all 
of the applicable actions specified in the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 737-35-
1099, dated April 9, 2007; except where the service bulletin 
specifies repairing the oxygen mask assembly, replace it with a new 
or modified oxygen mask assembly having an improved flow indicator. 
The corrective action and other specified action must be done before 
further flight.

    Note 1: Boeing Special Attention Service Bulletin 737-35-1099 
refers to B/E Aerospace Service Bulletin 174080-35-01, dated 
February 6, 2006; and Revision 1, dated May 1, 2006; as additional 
sources of service information for modifying the oxygen mask 
assembly by replacing the flow indicator with an improved flow 
indicator.

Alternative Methods of Compliance (AMOCs)

    (g)(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

[[Page 71832]]

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 December 10, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-24521 Filed 12-18-07; 8:45 am]
BILLING CODE 4910-13-P