E6-20863. Airworthiness Directives; Boeing Model 747 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 747 airplanes. This proposed AD would require an inspection of the number (No.) 2 and No. 3 windows on the left and right sides of the airplane to determine their part numbers, and related investigative and corrective actions if necessary. This proposed AD results from loss of a No. 3 window in-flight. We are proposing this AD to detect and correct cracking in the fail-safe interlayer of certain No. 2 and No. 3 glass windows, which could result in loss of the window and consequent rapid loss of cabin pressure. Loss of the window could also result in crew communication difficulties or incapacitation of the crew.

DATES:

We must receive comments on this proposed AD by January 22, 2007.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Gary Oltman, 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 submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2006-26441; Directorate Identifier 2006-NM-204-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone [phone]) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

We have received a report indicating that a number (No.) 3 window departed in-flight from a Boeing Model 747 airplane. Loss of the window resulted in rapid loss of cabin pressure, and the flightcrew made an emergency landing. The airplane had accumulated 36,131 total flight hours and 5,607 total flight cycles. Investigation revealed that a crack was present in the fail-safe interlayer of the No. 3 window, along the inner edge of the window's aluminum edge insert. When the structural inner glass pane cracked due to an electrical arcing event unassociated with the interlayer cracking, the interlayer was not able to support the cabin pressurization load and the window departed from the airplane. Subsequently, Boeing and some operators have also found cracks in the fail-safe interlayer of certain No. 2 and No. 3 glass windows, on many Model 747 airplanes. This condition, if not corrected, could result in loss of the window and consequent rapid loss of cabin pressure. Loss of the window could also result in crew communication difficulties or incapacitation of the crew.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-56A2012, dated August 24, 2006. The service bulletin describes procedures for doing a one-time inspection of the No. 2 and No. 3 windows on the left and right sides of the airplane to determine their part numbers (P/Ns) and doing related investigative and corrective actions if necessary. The service bulletin states that, instead of an inspection to determine the part number of a window, a review of maintenance records is acceptable if the part number of the window can be positively determined from that review. The service bulletin also states that if acrylic windows having P/N 65B07639-( ) or 65B07640-( ) are installed, no further inspections are necessary. The service bulletin also states that if the part number of the left No. 2 window, left No. 3 window, right No. 2 window, or right No. 3 window cannot be identified, you must assume that it is P/N 65B27042-1, 65B27043-1, 65B27042-2, or 65B27043-2, respectively. If glass windows having P/N 65B27042-( ), 65B27043-( ), 65B27046-( ), or 65B27047-( ) are installed, the service bulletin specifies doing the related investigative actions, which are repetitive detailed inspections for cracking or damage to the window. The corrective action is replacement of the affected window with a new window, if any of the following conditions are found during a detailed inspection: cracks in any fail-safe interlayer, cracks in a glass pane, chips in a structural glass pane, evidence of electrical arcing, or any non-clear damage to the window.

For the one-time inspection to determine the part numbers of the No. 2 and No. 3 windows, Table 1 of the service bulletin specifies doing the inspection at the earlier of the following compliance times: (1) Within 5,500 flight hours after the window was installed or 1,000 flight hours after the date of the service bulletin, whichever occurs last, or (2) within 2 years after the date of the service bulletin. Table 1 states that if the number of flight hours since the window was installed is not known, you must assume that the window is beyond the 5,500 flight-hour limit.

For a window having P/N 65B27042-( ) or 65B27043-( ), Table 2 of the service bulletin specifies doing the related investigative action (detailed inspection) at the earlier of the following compliance times: (1) Within 5,500 flight hours after the window was installed or 1,000 flight hours after the date of the service bulletin, whichever occurs last, or (2) within 2 years after the date of the service bulletin. Table 2 states that if the number of flight hours since the window was installed is not known, you must assume that the window is beyond the 5,500 flight-hour limit. Table 2 specifies repeating the detailed inspection at intervals not to exceed 3,000 flight hours or 3 years, whichever occurs first. Table 2 also specifies replacing the window before further flight after the inspection, if necessary.

For a window having P/N 65B27046-( ) or 65B27047-( ), Table 3 of the service bulletin specifies doing the related investigative action (detailed inspection) at the earlier of the following compliance times: (1) Within 22,000 flight hours after the window was installed or 1,000 flight hours after the date of the service bulletin, whichever occurs last, or (2) within 3 years after the date of the service bulletin. Table 3 states that if the number of flight hours since the window was installed is not known, you must assume that the window is beyond the 22,000 flight-hour limit. Table 3 specifies repeating the detailed inspection at intervals not to exceed 7,500 flight hours or 5 years, whichever occurs first. Table 3 also specifies replacing the window before further flight, if necessary.

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.

Interim Action

This is considered to be interim action until final action is identified, at which time we may consider further rulemaking.

Costs of Compliance

There are about 949 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 153 airplanes of U.S. registry. The proposed inspection to determine the window part numbers would take about 4 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 $48,960, or $320 per airplane.

The proposed detailed inspection, if necessary, would take about 1 work hour per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed detailed inspection for U.S. operators is $80 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-2006-26441; Directorate Identifier 2006-NM-204-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by January 22, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from loss of a number (No.) 3 window in-flight. We are issuing this AD to detect and correct cracking in the fail-safe interlayer of certain No. 2 and No. 3 glass windows, which could result in loss of the window and consequent rapid loss of cabin pressure. Loss of the window could also result in crew communication difficulties or incapacitation of the crew.

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, Related Investigative Actions, and Corrective Action

(f) Inspect the No. 2 and No. 3 windows on the left and right sides of the airplane to determine their part numbers (P/Ns), and do all the applicable related investigative and corrective actions, by accomplishing all of the actions specified in Accomplishment Instructions of Boeing Alert Service Bulletin 747-56A2012, dated August 24, 2006, as applicable. Do all of these actions at the compliance times specified in Tables 1, 2, and 3 of paragraph 1.E. of the service bulletin, as applicable, except as provided by paragraph (g) of this AD. A review of airplane maintenance records is acceptable in lieu of the inspection if the part numbers of the windows can be conclusively determined from that review. Repeat the related investigative and corrective actions thereafter at the interval specified in Table 2 or 3 of the service bulletin, as applicable.

Exception to Compliance Times

(g) Where Tables 1, 2, and 3 of paragraph 1.E. of Boeing Alert Service Bulletin 747-56A2012, dated August 24, 2006, specify counting the compliance time from “* * * after 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) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

(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.

Issued in Renton, Washington, on November 20, 2006.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.