E7-17586. Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 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 737-600, -700, -700C, -800, and -900 series airplanes. This proposed AD would require a one-time inspection to determine the material of the forward and aft gray water drain masts. For airplanes having composite gray water drain masts, this proposed AD would also require installation of a copper bonding jumper between a ground and the clamp on the tube of the forward and aft gray water composite drain masts. This proposed AD results from a report of charred insulation blankets and burned wires around the forward gray water composite drain mast found during an inspection of the forward cargo compartment on a Model 767-300F airplane. We are proposing this AD to prevent a fire near a composite drain mast and possible disruption of the electrical power system caused by a lightning strike on a composite drain mast, which could result in the loss of several functions essential for safe flight.

DATES:

We must receive comments on this proposed AD by October 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.
• U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room W12-140 on the ground floor of the West Building, 1200 New Jersey Avenue, SE., 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:

Marcia Smith, Aerospace Engineer, Cabin Safety and Environmental Systems Branch, ANM-150S, 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-2007-29116; Directorate Identifier 2007-NM-064-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 Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone [phone]) is located on the ground floor of the West 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, during an inspection of the forward cargo compartment on a Model 767-300F airplane, an operator found charred insulation blankets and burned wires around the forward gray water composite drain mast. Additional charring on the insulation blankets was noticed several feet away along the routing of the drain mast's ground wire and power wires. Analysis of the damaged parts revealed that a lightning strike on the composite drain mast caused the damage to the wires and insulation blankets. This condition, if not corrected, could cause disruption of electrical power and fire and heat damage to equipment in the event of a lightning strike on the composite drain mast, which could result in the potential loss of several functions essential for safe flight.

A design review of the gray water composite drain mast installation on Model 737, 757, 767, and 777 airplanes revealed that the installation of a heavier bonding jumper is necessary to provide adequate lightning protection to the gray water composite drain mast installation. The subject area on Model 737-600, -700, -700C, -800, and -900 airplanes is almost identical to that on the affected Model 767-300F airplane. Therefore, Model 737-600, -700, -700C, -800, and -900 series airplanes might be subject to the unsafe condition revealed on the Model 767-300F airplane. We are currently considering additional rulemaking to address the identified unsafe condition on Model 757, 767, and 777 airplanes.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 737-30-1056, dated February 28, 2007. The service bulletin describes procedures for installing a 135-ampere copper bonding jumper between a ground and the clamp on the tube of the forward and aft gray water composite drain mast.

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 1,540 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Inspection to determine gray water drain mast material	1	$80	None	$80	420	$33,600.
Installation of bonding jumper	Between 2 and 4 (depending on airplane configuration)	$80	Between $7 and $15, depending on kit	Between $167 and $335	Up to 420	Between $70,140 and $140,700.

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-2007-29116; Directorate Identifier 2007-NM-064-AD.

Comments Due Date

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

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from a report of charred insulation blankets and burned wires around the forward gray water composite drain mast found during an inspection of the forward cargo compartment on a Model 767-300F airplane. We are issuing this AD to prevent a fire near a composite drain mast and possible disruption of the electrical power system caused by a lightning strike on a composite drain mast, which could result in the loss of several functions essential for safe flight.

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 To Determine Material of Gray Water Drain Masts

(f) Within 60 months after the effective date of this AD, inspect the forward and aft gray water drain masts to determine whether the drain masts are made of aluminum or composite. A review of airplane maintenance records is acceptable in lieu of this inspection if the material of the forward and aft gray water drain masts can be conclusively determined from that review.

(1) For any aluminum gray water drain mast identified during the inspection or records check required by paragraph (f) of this AD, no further action is required by this paragraph for that drain mast only.

(2) For any composite gray water drain mast identified during the inspection or records check required by paragraph (f) of this AD, do the actions specified in paragraph (g) of this AD.

Installation of Bonding Jumper

(g) For any composite gray water drain mast identified during the inspection or records check required by paragraph (f) of this AD: Within 60 months after the effective date of this AD, install a 135-ampere copper bonding jumper between a ground and the clamp on the tube of the gray water composite drain mast, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-30-1056, dated February 28, 2007.

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Seattle Aircraft Certification Office, 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 August 28, 2007.

Stephen P. Boyd,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.