2010-11901. Airworthiness Directives; The Boeing Company Model 747-400 and 747-400D Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Model 747-400 and 747-400D series airplanes. This proposed AD would require installing aluminum gutter reinforcing brackets to the forward and aft drip shield gutters of the main equipment center (MEC); and adding a reinforcing fiberglass overcoat to the top surface of the MEC drip shield, including an inspection for cracking and holes in the MEC drip shield, and corrective actions if necessary. This proposed AD also provides for an option to install an MEC drip shield drain system, which, if accomplished, would extend the compliance time for adding the reinforcing fiberglass overcoat to the top surface of the MEC drip shield. This proposed AD results from a report indicating that an operator experienced a multi-power system loss in-flight of #1, #2, and #3 alternating current (AC) electrical power systems located in the MEC. We are proposing this AD to prevent water penetration into the MEC, which could result in the loss of flight critical systems.

DATES:

We must receive comments on this proposed AD by July 6, 2010.

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 proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; e-mail [e-mail]; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221.

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:

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 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-2010-0480; Directorate Identifier 2010-NM-035-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 received a report indicating that an operator experienced a multi-power system loss in-flight of #1, #2, and #3 AC electrical power systems located in the main equipment center (MEC). The forward MEC drip shield gutters and exhaust plenum have each been identified as part of the leak path into the MEC. Multiple operators have reported MEC drip shield gutter and upper surface cracks. These cracks can allow water to penetrate the MEC drip shield and enter the MEC. This condition, if not corrected, could allow water penetration into the MEC, which could result in the loss of flight critical systems.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-25A3555, dated November 4, 2009. The service bulletin describes procedures for installing aluminum gutter reinforcing brackets to the forward and aft drip shield gutters of the main equipment center (MEC). The service bulletin also describes procedures for adding a reinforcing fiberglass overcoat to the top surface of the MEC drip shield, including a general visual inspection for cracking and holes in the top surface of the MEC drip shield, and corrective actions if necessary. The corrective actions include repairing any crack or hole found. The service bulletin also describes procedures for an option to install an MEC drip shield drain system, which, if accomplished, would extend the compliance time for adding the reinforcing fiberglass overcoat.

FAA's Determination and Requirements of This Proposed AD

We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. This proposed AD would require accomplishing the actions specified in the service information described previously.

Costs of Compliance

We estimate that this proposed AD would affect 71 airplanes of U.S. registry. The following table provides the estimated costs, depending on airplane configuration, for U.S. operators to comply with this proposed AD.

Table—Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per product	Number of U.S.- registered airplanes	Fleet cost
Install Brackets	Between 7 and 8 1	$85	None	Up to $680 1	71	Up to $48,280.1
Add Overcoat	Between 11 and 12 1	85	None	Up to $1,020 1	71	Up to $72,420.1
Install Optional MEC Drip Shield Drain System	Between 12 and 13 1	85	Up to $8,982 1	Up to $10,087 1	71	Up to $716,177.1
1 Depending on work package.

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 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 this 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• 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 FAA amends § 39.13 by adding the following new AD:

The Boeing Company: Docket No. FAA-2010-0480; Directorate Identifier 2010-NM-035-AD.

Comments Due Date

(a) We must receive comments by July 6, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to The Boeing Company Model 747-400 and 747-400D series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-25A3555, dated November 4, 2009.

Subject

(d) Air Transport Association (ATA) of America Code 25: Equipment/Furnishings.

Unsafe Condition

(e) This AD results from a report indicating that an operator experienced a multi-power system loss in-flight of #1, #2, and #3 alternating current electrical power systems located in the main equipment center (MEC). The Federal Aviation Administration is issuing this AD to prevent water penetration into the MEC, which could result in loss of flight critical systems.

Compliance

(f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Modification

(g) Do the actions specified in either paragraph (g)(1) or (g)(2) of this AD, at the times specified in those paragraphs, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-25A3555, dated November 4, 2009 (“the service bulletin”).

(1) Within 24 months after the effective date of this AD, install the reinforcing brackets of the MEC drip shield aluminum gutter, in accordance with Work Package 1 of the Accomplishment Instructions of the service bulletin; and add a reinforcing fiberglass overcoat to the top surface of the MEC drip shield, including doing a general visual inspection for cracking and holes in the top surface of the MEC drip shield, and doing all applicable corrective actions, in accordance with Work Package 3 of the Accomplishment Instructions of the service bulletin. Do all applicable corrective actions before further flight after doing the general visual inspection.

(2) Do the actions specified in paragraphs (g)(2)(i) and (g)(2)(ii) of this AD.

(i) Within 24 months after the effective date of this AD, install the reinforcing brackets of the MEC drip shield aluminum gutter, in accordance with Work Package 1 of the Accomplishment Instructions of the service bulletin; and install a MEC drip shield drain system, in accordance with Work Package 2 of the Accomplishment Instructions of the service bulletin.

(ii) Within 96 months after the effective date of this AD, add a reinforcing fiberglass overcoat to the top surface of the MEC drip shield, including doing a general visual inspection for cracking and holes in the top surface of the MEC drip shield, and doing all applicable corrective actions, in accordance with Work Package 3 of the Accomplishment Instructions of the service bulletin. Do all applicable corrective actions before further flight after doing the general visual inspection.

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 using the procedures found in 14 CFR 39.19. Send information to ATTN: 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]. Information may be e-mailed to: [e-mail].

(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 principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

Issued in Renton, Washington, on May 5, 2010.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.