[Federal Register Volume 72, Number 200 (Wednesday, October 17, 2007)]
[Proposed Rules]
[Pages 58766-58768]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-20466]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0046; Directorate Identifier 2007-NM-173-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
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 all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes. This proposed AD would require repetitive inspections for 
any cracking of or damage to the left side and right side flight deck 
No. 2, No. 4, and No. 5 windows and corrective actions if necessary. 
This proposed AD results from reports of in-flight departure and 
separation of the flight deck windows. We are proposing this AD to 
detect and correct cracking in the vinyl interlayer or damage to the 
structural inner glass panes of the flight deck No. 2, No. 4, and No. 5 
windows, which could result in loss of a window and rapid loss of cabin 
pressure. Loss of cabin pressure could cause crew communication 
difficulties or crew incapacitation.

DATES: We must receive comments on this proposed AD by December 3, 
2007.

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: Wayne Lockett, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6447; 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-2007-0046; 
Directorate Identifier 2007-NM-173-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 one report of in-flight departure of the flight 
deck No. 3 window, on a Boeing Model 747 series airplane, which 
resulted in rapid loss of cabin pressure and an emergency landing. That 
airplane had accumulated 36,131 total flight hours and 5,607 total 
flight cycles. We have also received two reports of in-flight 
separation of the left side flight deck No. 5 window, on two Boeing 
Model 737 series airplanes. One of the Model 737 series airplanes 
experienced cabin pressure loss at 12,500 feet due to separation of the 
forward, aft, and upper edges of the left side flight deck No. 5 
window. That airplane had accumulated 25,673 total flight hours and 
15,669 total flight cycles. The other Model 737 series airplane 
experienced a pressure leak at 29,000 feet due to partial separation of 
the upper aft corner of the left side flight deck No. 5 window. That 
airplane had accumulated 28,139 total flight hours and 16,566 total 
flight cycles. Vinyl interlayer cracking of the flight deck No. 2, No. 
4, and No. 5 windows could decrease the load carrying capability of the 
affected windows during cabin pressurization if the structural glass 
pane of the window becomes broken. Vinyl interlayer cracking could also 
decrease the bird impact resistance capability of the flight deck No. 2 
and No. 4 windows. Cracking in the vinyl interlayer or damage to the 
structural inner glass panes of the flight deck No. 2, No. 4, and No. 5 
windows, if not corrected, could result in loss of a

[[Page 58767]]

window and rapid loss of cabin pressure. Loss of cabin pressure could 
cause crew communication difficulties or crew incapacitation.
    On July 18, 2007, we issued AD 2007-15-10, amendment 39-15139 (72 
FR 41438, July 30, 2007), to address the unsafe condition on all Model 
747 airplanes. A correction was issued on September 10, 2007 (72 FR 
53923, September 21, 2007), to fix a typographical error in AD 2007-15-
10.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 737-56A1023, dated 
May 24, 2007. The service bulletin describes procedures for doing 
repetitive internal and external detailed inspections for any cracking 
of or damage to the left side and right side flight deck No. 2, No. 4, 
and No. 5 windows that exceeds the limits given in the Accomplishment 
Instructions of the service bulletin. The service bulletin also 
describes procedures for accomplishing corrective actions if necessary, 
which include replacing any cracked or damaged window with a new or 
serviceable window.
    The service bulletin specifies an initial compliance time ranging 
between 6 months and 24 months, depending on the window location and 
number of window flight hours. If a replacement window is not new or 
has an unknown number of flight hours, the service bulletin specifies 
accomplishing the initial inspection before installation. If a 
replacement window is new or has zero flight hours, the service 
bulletin specifies accomplishing the initial inspection at the 
following times: (1) 7,500 window flight hours or 36 months, whichever 
occurs first, for flight deck No. 2 windows, and (2) 6,000 window 
flight hours or 24 months, whichever occurs first, for flight deck No. 
4 and No. 5 windows. The service bulletin specifies a repetitive 
interval of (1) 7,500 window flight hours or 36 months, whichever 
occurs first, for flight deck No. 2 windows, and (2) 6,000 window 
flight hours or 24 months, whichever occurs first, for flight deck No. 
4 and No. 5 windows. The service bulletin specifies accomplishing the 
corrective actions before further flight.
    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.

Costs of Compliance

    There are about 2,685 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 799 airplanes of 
U.S. registry. The proposed inspections would take about 2 work hours 
per airplane, at an average labor rate of $80 per work hour. Based on 
these figures, the estimated cost of the proposed AD for U.S. operators 
is $127,840, or $160 per airplane, per inspection cycle.

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-2007-0046; Directorate Identifier 2007-NM-
173-AD.

Comments Due Date

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

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Boeing Model 737-100, -200, -200C, -
300, -400, and -500 series airplanes, certificated in any category.

Unsafe Condition

    (d) This AD results from reports of in-flight departure and 
separation of flight deck windows. We are issuing this AD to detect 
and correct cracking in the vinyl interlayer or damage to the 
structural inner glass panes of the flight deck No. 2, No. 4, and 
No. 5 windows, which could result in loss of a window and rapid loss 
of cabin pressure. Loss of cabin pressure could cause crew 
communication difficulties or crew incapacitation.

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.

Repetitive Inspections and Replacement

    (f) At the applicable times specified in Tables 1, 2, and 3 of 
paragraph 1.E. of Boeing Alert Service Bulletin 737-56A1023, dated 
May 24, 2007, except as provided by paragraph (g) of this AD: Do the 
internal and external detailed inspections for any cracking of or 
damage to the left side and right side flight deck No. 2, No. 4, and 
No. 5 windows and do the applicable corrective actions before 
further flight, by accomplishing all of the applicable actions 
specified in the Accomplishment Instructions of the service

[[Page 58768]]

bulletin. Repeat the inspections thereafter at the applicable 
interval specified in paragraph 1.E. of the service bulletin.

Exception to Compliance Times

    (g) Where Tables 1, 2, and 3 of paragraph 1.E. of Boeing Alert 
Service Bulletin 737-56A1023, dated May 24, 2007, specify counting 
the compliance time from ``* * * the date on this service 
bulletin,'' this AD requires counting the compliance time from the 
effective date of this AD.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
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.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane, and the approval must specifically refer to this 
AD.
    (4) Installation of metallic window blanks at cockpit eyebrow 
windows No. 4 and No. 5 in accordance with Supplemental Type 
Certificate ST01630SE is approved as an AMOC to the initial and 
repetitive inspections for the flight deck No. 4 and No. 5 windows 
required by paragraph (f) of this AD. All other applicable actions 
required by paragraph (f) of this AD must be fully complied with.

    Issued in Renton, Washington, on October 5, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-20466 Filed 10-16-07; 8:45 am]
BILLING CODE 4910-13-P