
[Federal Register Volume 76, Number 57 (Thursday, March 24, 2011)]
[Proposed Rules]
[Pages 16579-16582]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-6931]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-0258; Directorate Identifier 2010-NM-191-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Model 737-600, -700, 
-700C, -800, -900, and -900ER 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 the 
products listed above. This proposed AD would require installing two 
warning level indicator lights on each of the P1-3 and P3-1 instrument 
panels in the flight compartment. This proposed AD would also require 
revising the airplane flight manual to remove certain requirements of 
previous AD actions, and to advise the flightcrew of the following 
changes: Revised non-normal procedures to use when a cabin altitude 
warning or rapid depressurization occurs, and revised cabin 
pressurization procedures for normal operations. This proposed AD was 
prompted by a design change in the cabin altitude warning system that 
would address the identified unsafe condition. We are proposing this AD 
to prevent failure of the flightcrew to recognize and react to a valid 
cabin altitude warning horn, which could result in incapacitation of 
the flightcrew due to hypoxia (lack of oxygen in the body), and 
consequent loss of control of the airplane.

DATES: We must receive comments on this proposed AD by May 9, 2011.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to 
http:[sol][sol]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: Deliver to Mail address above 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:[sol][sol]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.

Examining the AD Docket

    You may examine the AD docket on the Internet at 
http:[sol][sol]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

[[Page 16580]]

(phone: 800-647-5527) is in the ADDRESSES section. Comments will be 
available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Jeffrey W. Palmer, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; phone: (425) 917-6472; fax: (425) 917-6590; e-mail: 
jeffrey.w.palmer@faa.gov.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2011-0258; 
Directorate Identifier 2010-NM-191-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:[sol][sol]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

    The Model 737 airplanes cabin altitude warning is an intermittent 
horn that sounds when cabin altitude exceeds 10,000 feet. The same 
intermittent warning horn sound is used by the takeoff configuration 
warning system (TCWS) to warn of an unsafe airplane configuration for 
takeoff. The TCWS warning functionality is inhibited by air/ground 
logic when the airplane is in flight. However, the Model 737 airplane's 
cabin altitude warning system design does not currently incorporate a 
dedicated means of positively identifying the warning horn as a cabin 
altitude warning or a takeoff configuration warning. There are 
approximately 25 known instances where flightcrews misinterpreted a 
valid cabin altitude warning as a takeoff configuration warning.
    Failure of the flightcrew to recognize and react to a valid cabin 
altitude warning horn could result in incapacitation of the flightcrew 
due to hypoxia (lack of oxygen in the body), and consequent loss of 
control of the airplane. To address this unsafe condition, we issued 
the following ADs.
    On July 7, 2003, we issued related AD 2003-14-08, Amendment 39-
13227 (68 FR 41519, July 14, 2003). That AD applies to all Boeing Model 
737-600, 737-700, 737-700C, 737-800, 737-900, 757, and 767 series 
airplanes. That AD requires revising the airplane flight manual (AFM) 
to advise the flightcrew to don oxygen masks as a first and immediate 
step when a cabin altitude warning occurs.
    On June 15, 2006, we issued related AD 2006-13-13, Amendment 39-
14666 (71 FR 35781, June 22, 2006). (A correction of that AD was 
published in the Federal Register on July 3, 2006 (71 FR 37980).) That 
AD applies to all Model 737 airplanes. That AD requires revising the 
AFM to advise the flightcrew of improved procedures for pre-flight 
setup of the cabin pressurization system, as well as improved 
procedures for interpreting and responding to the cabin altitude/
configuration warning horn. That AD resulted from reports that 
airplanes had failed to pressurize, and that the flightcrews failed to 
react properly to the cabin altitude warning horn.
    On October 24, 2008, we issued related AD 2008-23-07, Amendment 39-
15728 (73 FR 66512, November 10, 2008), for all Model 737 airplanes. 
That AD requires revising the AFM to include a new flightcrew briefing 
that must be done before the first flight of the day and following any 
change in flightcrew members, and to advise the flightcrew of this 
additional briefing. That AD resulted from continuing reports that 
flightcrews have failed to recognize and react properly to the cabin 
altitude warning horn.
    The preambles to AD 2006-13-13 and AD 2008-23-07 explain that the 
revisions to the AFM required by those ADs are considered to be interim 
action. The manufacturer had advised us that it was developing a design 
change in the cabin altitude warning system that would address the 
identified unsafe condition(s), and that once this design change was 
developed, approved, and available, the FAA might consider additional 
rulemaking. The manufacturer now has developed such a modification, and 
we have determined that further rulemaking is necessary; this proposed 
AD follows from that determination. We can better ensure long-term 
continued operational safety by modifications or design changes to 
remove the source of the problem, rather than by AFM revisions alone.

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-31A1332, Revision 1, 
dated June 24, 2010. The service information describes procedures for 
installing two warning level indicator lights on each of the P1-3 and 
P3-1 instrument panels in the flight compartment. The installation 
includes installing a new circuit breaker and changing certain wire 
bundles.

FAA's Determination

    We are proposing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

    This proposed AD would require accomplishing the actions specified 
in the service information described previously, except as discussed 
under ``Difference Between the Proposed AD and the Service 
Information.'' The proposed AD would also require revising the 
Limitations Section of the AFM to remove certain requirements of 
previous AD actions, and to advise the flightcrew of the following 
changes: Revised non-normal procedures to use when a cabin altitude 
warning or rapid depressurization occurs, and revised cabin 
pressurization procedures for normal operations.

Difference Between the Proposed AD and the Service Information

    The effectivity in Boeing Alert Service Bulletin 737-31A1332, 
Revision 1, dated June 24, 2010, identifies Model 737-600, -700, -700C, 
-800, -900, and -900ER series airplanes; however, it does not include 
all applicable serial numbers for airplanes that are subject to the 
identified unsafe condition. The actions for Group 1 airplanes, as 
specified in this service bulletin, must be done on additional 
airplanes, as identified in the applicability of this proposed AD.
    Groups 8 through 21 airplanes are also included in the effectivity 
of the service bulletin; however, the actions required by this proposed 
AD would affect only Groups 1 through 7 airplanes. Therefore, 
concurrent actions, which specify installing a new P5-16 cabin altitude 
and rate of climb panel and cabin altitude and differential pressure 
indicator, would not be required by this proposed AD.

Costs of Compliance

    We estimate that this proposed AD would affect 650 airplanes of 
U.S. registry. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

[[Page 16581]]



                                                                 Table--Estimated Costs
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                                                                                                                    Number of U.S.-
             Action                   Work hours      Average labor rate         Parts         Cost per product       registered          Fleet cost
                                                           per hour                                                    airplanes
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Installation of warning           Between 31 and 64.                 $85  Between $2,132 and  Between $4,767 and                 650  Between $3,098,550
 indicator lights.                                                         $3,192.             $8,632.                                 and $5,610,800.
AFM revision....................  2.................                  85  $0................  $170..............                 650  $110,500.
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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 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),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

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 
airworthiness directive (AD): Docket No. FAA-2011-0258; Directorate 
Identifier 2010-NM-191-AD.

Comments Due Date

    (a) We must receive comments by May 9, 2011.

Affected ADs

    (b) This AD affects the ADs identified in paragraphs (b)(1), 
(b)(2), and (b)(3) of this AD. This AD does not supersede the 
requirements of these ADs.
    (1) AD 2003-14-08, Amendment 39-13227.
    (2) AD 2006-13-13, Amendment 39-14666.
    (3) AD 2008-23-07, Amendment 39-15728.

Applicability

    (c) This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, -900, and -900ER series airplanes, Groups 1 through 7 
airplanes, certificated in any category; identified in Boeing Alert 
Service Bulletin 737-31A1332, Revision 1, dated June 24, 2010; or 
having any serial number identified in table 1 of this AD.

                         Table 1--Serial Numbers
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                             Serial Numbers
 
22940.
33546 through 33582 inclusive.
33717 through 33719 inclusive.
33758 through 33759 inclusive.
33794 through 33797 inclusive.
33804 through 33822 inclusive.
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Subject

    (d) Air Transport Association (ATA) of America Code 31, 
Instruments.

Unsafe Condition

    (e) This AD was prompted by a design change in the cabin altitude 
warning system that would address the identified unsafe condition. The 
Federal Aviation Administration is issuing this AD to prevent failure 
of the flightcrew to recognize and react to a valid cabin altitude 
warning horn, which could result in incapacitation of the flightcrew 
due to hypoxia (lack of oxygen in the body) and consequent loss of 
control of the airplane.

Compliance

    (f) Comply with this AD within the compliance times specified, 
unless already done.

Installation

    (g) For Groups 1 through 7 airplanes, as identified in Boeing Alert 
Service Bulletin 737-31A1332, Revision 1, dated June 24, 2010; and 
airplanes having any serial number identified in table 1 of this AD: 
Within 36 months after the effective date of this AD, install two 
warning level indicator lights on each of the P1-3 and P3-1 instrument 
panels in the flight compartment, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-31A1332, Revision 1, 
dated June 24, 2010. The actions required for Group 1 airplanes also 
apply to the airplanes identified in table 1 of this AD.

Airplane Flight Manual (AFM) Revisions

    (h) Before further flight after doing the installation required by 
paragraph (g) of this AD, do the actions specified in paragraphs 
(h)(1), (h)(2), and (h)(3) of this AD.
    (1) Revise the Limitations Section of the applicable Boeing 737 AFM 
by doing the following action: Delete the ``CABIN ALTITUDE WARNING 
TAKEOFF BRIEFING'' added by AD 2008-23-07, Amendment 39-15728.
    (2) Revise the Non-Normal Procedures Section of the applicable 
Boeing 737

[[Page 16582]]

AFM by doing the actions specified in paragraphs (h)(2)(i), (h)(2)(ii), 
(h)(2)(iii), and (h)(2)(iv) of this AD.
    (i) Delete the procedure ``WARNING HORN--CABIN ALTITUDE OR 
CONFIGURATION'' added by AD 2006-13-13, Amendment 39-14666. If the 
title of this procedure has been changed according to FAA alternative 
method of compliance (AMOC) letter 130S-09-134a, dated April 28, 2009, 
delete the procedure that was approved according to this AMOC letter.
    (ii) Delete the procedure entitled ``CABIN ALTITUDE WARNING OR 
RAPID DEPRESSURIZATION'' added by AD 2003-14-08, Amendment 39-13227.
    (iii) If the procedure entitled ``CABIN ALTITUDE (Airplanes with 
the CABIN ALTITUDE lights installed)'' is currently contained in the 
applicable Boeing 737 AFM, delete the procedure entitled ``CABIN 
ALTITUDE (Airplanes with the CABIN ALTITUDE lights installed).''
    (iv) Add the following statement. This may be done by inserting a 
copy of this AD into the applicable AFM.

           ``CABIN ALTITUDE WARNING OR RAPID DEPRESSURIZATION
     Condition: The CABIN ALTITUDE warning light illuminates or the
     intermittent warning horn sounds in flight above 10,000 ft MSL.
RECALL
Oxygen Masks and Regulators..................  ON, 100%.
Crew Communications..........................  ESTABLISH.
REFERENCE
Pressurization Mode Selector.................  MANUAL.
Outflow Valve Switch.........................  CLOSE.
If Cabin Altitude is uncontrollable:
Emergency Descent (If Required)..............  INITIATE.
Passenger Oxygen Switch......................  ON.
Thrust Levers................................  CLOSE.
Speed Brakes.................................  FLIGHT DETENT.
 Target Speed................................  VMO/MMO.''
 

    (3) Revise the Normal Procedures Section of the applicable Boeing 
737 AFM by doing the actions specified in paragraphs (h)(3)(i) and 
(h)(3)(ii) of this AD.
    (i) Delete the ``CABIN ALTITUDE WARNING TAKEOFF BRIEFING'' 
procedure added by AD 2008-23-07.
    (ii) Add the following statement. This may be done by inserting a 
copy of this AD into the applicable AFM.

    ``For normal operations, the pressurization mode selector should 
be in AUTO prior to takeoff.

    Note 1: When statements identical to those specified in 
paragraphs (h)(2)(iv) and (h)(3)(ii) of this AD have been included 
in the general revisions of the AFM, the general revisions may be 
inserted into the AFM, and the copies of this AD may be removed from 
the AFM.

Terminating Action for Affected ADs

    (i) Accomplishment of the requirements of this AD terminates the 
requirements of the ADs identified in paragraphs (i)(1), (i)(2), and 
(i)(3) of this AD for only the airplanes identified in paragraph (c) of 
this AD.
    (1) AD 2003-14-08: The requirements specified in Table 1 and Figure 
1 of that AD.
    (2) AD 2008-23-07: All requirements of that AD.
    (3) AD 2006-13-13: All requirements of that AD.

Special Flight Permit

    (j) Special flight permits, as described in Section 21.197 and 
Section 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 
21.199), are not allowed.

Alternative Methods of Compliance (AMOCs)

    (k)(1) The Manager, Seattle ACO, FAA, has the authority to approve 
AMOCs for this AD, if requested using the procedures found in 14 CFR 
39.19. In accordance with 14 CFR 39.19, send your request to your 
principal inspector or local Flight Standards District Office, as 
appropriate. If sending information directly to the manager of the ACO, 
send it to the attention of the person identified in the Related 
Information section of this AD. Information may be e-mailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager of 
the local flight standards district office/certificate holding district 
office.

Related Information

    (l) For more information about this AD, contact Jeffrey W. Palmer, 
Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; phone: (425) 917-6472; fax: (425) 917-6590; e-
mail: jeffrey.w.palmer@faa.gov.
    (m) For service information identified in this 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, the 
FAA, 1601 Lind Avenue, SW., Renton, Washington. For information on the 
availability of this material at the FAA, call 425-227-1221.

    Issued in Renton, Washington, on March 14, 2011.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-6931 Filed 3-23-11; 8:45 am]
BILLING CODE 4910-13-P


