E7-20466. 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).

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: [phone].
• 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 [phone]) 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 [phone]; fax [phone].

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 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.

§ 39.13

[Amended]

2. The Federal Aviation Administration (FAA) amends § 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 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.