E7-12836. Airworthiness Directives; Boeing Model 747-400, 747-400D, and 747-400F Series Airplanes; Model 757-200 Series Airplanes; and Model 767-200, 767-300, and 767-300F 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 certain Boeing Model 747-400, 747-400D, 747-400F, 757-200, 767-200, 767-300, and 767-300F series airplanes. This proposed AD would require inspecting to determine the date code of the time delay relay for the cargo fire suppression system, and replacing the relay if necessary. This proposed AD results from a report indicating that failure of a time delay relay on an ELMS (electrical load management system) panel led to testing of other time delay relays at Boeing and at the supplier. Similar relays are used in the cargo fire suppression system. The time delay relay controls when the fire bottles discharge. We are proposing this AD to ensure there is sufficient fire suppressant to control a cargo fire if the airplane is more than the relay delay time from a suitable airport, which could result in an uncontrollable fire in the cargo compartment.

DATES:

We must receive comments on this proposed AD by August 17, 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 9:00 a.m. and 5:00 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:

Binh V. Tran, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, 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-2007-28380; Directorate Identifier 2007-NM-088-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 failure of a time delay relay on a Boeing Model 777 ELMS (electrical load management system) panel led to testing of other time delay relays at Boeing and at the supplier. Similar relays are used in the cargo fire suppression system. Although there have been no reported in-service failures of the cargo fire suppression time delay relays, the testing showed that, at elevated temperatures, thermal expansion can cause pre-existing cracks in the timing module substrates to widen and cause an electrical open circuit that prevents power from reaching the relay coil. The relay operates normally at reduced temperatures.

The time delay relays of the fire suppression system in Boeing Model 747-400, 747-400D, 747-400F, 757-200, 767-200, 767-300, and 767-300F series airplanes can have the same condition. There are two Halon bottles in the cargo fire suppression system on these airplanes. The first bottle discharges immediately after the cargo fire discharge switch is pressed. The second bottle of fire suppressant discharges after a period of time controlled by the time delay relay. If there is a cargo fire and the time delay relay has failed, the second bottle will not discharge. Although the first bottle discharges, the available Halon may not be enough to control a cargo fire. This condition, if not corrected, could result in insufficient fire suppressant to control a cargo fire if the airplane is more than the relay delay time from a suitable airport, which could result in an uncontrollable fire in the cargo compartment.

Relevant Service Information

We have reviewed the Boeing service bulletins listed in the following table.

Boeing Service Bulletins

Boeing Special Attention Service Bulletin—	For Boeing Model—
747-26-2281, dated July 24, 2006	747-400, 747-400D, and 747-400F series airplanes.
757-26-0051, dated July 28, 2006	757-200 series airplanes.
767-26-0131, dated July 24, 2006	767-200, 767-300, and 767-300F series airplanes.

The service bulletins describe procedures for inspecting the time delay relay in the Main Equipment Center to determine if it was manufactured during a certain date range, and replacing any relay within that date range with a relay not manufactured during that date range, or with a relay that has been tested by the supplier and found to be unaffected by the thermal expansion. The service bulletins permit flight for 30 days after finding a relay that was manufactured within the suspect date range. 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.

Operators should note that, consistent with the Boeing service information, this proposed AD allows operators to continue flight for 30 days after finding a relay that was manufactured within the suspect date range. In making this determination, we consider that, in the case of this AD, long-term continued operational safety is adequately assured by replacing a suspect relay within the specified time limit.

Costs of Compliance

There are about 1,871 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 702 airplanes of U.S. registry. The proposed inspection 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 AD for U.S. operators is $56,160, or $80 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.

§ 39.13

[Amended]

2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-28380; Directorate Identifier 2007-NM-088-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by August 17, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to the Boeing airplane models, certificated in any category, identified in the service bulletins specified Table 1 of this AD.

Table 1.—Applicability of This AD

Boeing model—	As identified in Boeing Special Attention Service Bulletin—
747-400, 747-400D, and 747-400F series airplanes	747-26-2281, dated July 24, 2006.
757-200 series airplanes	757-26-0051, dated July 28, 2006.
767-200, -300, and -300F series airplanes	767-26-0131, dated July 24, 2006.

Unsafe Condition

(d) This AD results from a report indicating that failure of a time delay relay on a Boeing Model 777 ELMS (electrical load management system) panel led to testing of other time delay relays at Boeing and at the supplier. Similar relays are used in the cargo fire suppression system. We are issuing this AD to ensure there is sufficient fire suppressant to control a cargo fire if the airplane is more than the relay delay time from a suitable airport, which could result in uncontrollable fire in the cargo compartment.

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.

Service Bulletin Reference

(f) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of the following service bulletins, as applicable:

(1) For Model 747-400, 747-400D, and 747-400F series airplanes: Boeing Special Attention Service Bulletin 747-26-2281, dated July 24, 2006;

(2) For Model 757-200 series airplanes: Boeing Special Attention Service Bulletin 757-26-0051, dated July 28, 2006; and

(3) For Model 767-200, -300, and -300F series airplanes: Boeing Special Attention Service Bulletin 767-26-0131, dated July 24, 2006.

Inspection

(g) Within 24 months after the effective date of this AD: Do a general visual inspection of the part number (P/N) TDH6103-1204, -1804, and -6003 time delay relay, as applicable, in the Main Equipment Center to determine if the relay was manufactured during a certain date range, in accordance with the applicable service bulletin.

Replacement

(h) Within 30 days after finding a relay manufactured during the date range specified in the service bulletin, as required by paragraph (g) of this AD: Replace the relay with a relay that was not manufactured during the specified date range, or with a relay that has been tested by the supplier and found to be unaffected by thermal expansion, in accordance with the applicable service bulletin.

Parts Installation

(i) As of the effective date of this AD, no person may install a time delay relay, P/N TDH6103-1204, -1804, or -6003, on any airplane if the relay has a date code between 0000 and 0343 and does not have an additional date code with the letter “T.”

Alternative Methods of Compliance (AMOCs)

(j)(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.

Issued in Renton, Washington, on June 22, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.