2011-2952. Airworthiness Directives; The Boeing Company Model 747-400 and -400F 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 the products listed above. This proposed AD would require a general visual inspection for cracks and holes of the main equipment center (MEC) drip shields, and repairs if necessary; installation of a fiberglass reinforcing overcoat; and, for certain airplanes, installation of stiffening panels to the MEC drip shields. This proposed AD was prompted by a report of a loss of bus control unit number 1 and generator control units numbers 1 and 2 while the airplane was on the ground, and multiple operator reports of cracked MEC drip shields. 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 March 28, 2011.

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: Deliver to Mail address above 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 (phone: [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 & Environmental Systems Branch, ANM-150S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone: [phone]; fax: [phone]; e-mail: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2011-0041; Directorate Identifier 2010-NM-227-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 a report of a loss of bus control unit number 1 and generator control units numbers 1 and 2 while the airplane was on the ground, and multiple operators have reported cracked main equipment center (MEC) drip shields. Cracking in the MEC drip shield and exhaust plenum has been identified as part of the water leak path into the MEC. This condition, if not corrected, could result in water penetration into the MEC, which could result in the loss of flight critical systems.

Relevant Service Information

We reviewed Boeing Alert Service Bulletin 747-25A3588, dated July 19, 2010. The service information describes procedures for performing a general visual inspection of the MEC drip shield for cracks and holes, performing repairs if necessary, and installing a fiberglass reinforcing overcoat to the MEC drip shield. Additionally, for airplanes identified as Groups 1 and 3, the service information describes procedures for installing MEC drip shield panel stiffeners.

FAA's Determination

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

Proposed AD Requirements

This proposed AD would require accomplishing the actions specified in the service information described previously.

Costs of Compliance

We estimate that this proposed AD affects 41 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Inspection and installation: Groups 1, 3 (24 airplanes)	20 work-hours × $85 per hour = $1,700	$1,109	$2,809	$67,416
Inspection and installation: Group 2 (17 airplanes)	17 work-hours × $85 per hour = $1,445	Negligible	1,445	24,565

We estimate the following costs to do any necessary repairs that would be required based on the results of the proposed inspection. We have no way of determining the number of aircraft that might need these repairs.

On-Condition Costs

Action	Labor cost	Parts cost	Cost per airplane
Hole repair	1 work-hour × $85 per hour = $85 per hole	Negligible	$85 per hole.

According to the manufacturer, some of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our cost estimate.

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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

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 airworthiness directive (AD):

The Boeing Company: Docket No. FAA-2011-0041; Directorate Identifier 2010-NM-227-AD.

Comments Due Date

(a) We must receive comments by March 28, 2011.

Affected ADs

(b) None.

Applicability

(c) This AD applies to The Boeing Company Model 747-400 and -400F series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 747-25A3588, dated July 19, 2010.

Subject

(d) Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 25, Equipment/Furnishings.

Unsafe Condition

(e) This AD was prompted by a report of a loss of bus control unit number 1 and generator control units numbers 1 and 2 while the airplane was on the ground, and multiple operator reports of cracked main equipment center (MEC) drip shields. We are issuing this AD to prevent water penetration into the MEC, which could result in the loss of flight critical systems.

Compliance

(f) Comply with this AD within the compliance times specified, unless already done.

Inspection

(g) Within 24 months after the effective date of this AD, do the actions specified in paragraph (g)(1) or (g)(2) of this AD, as applicable, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-25A3588, dated July 19, 2010.

(1) For Group 1 and Group 3 airplanes, as identified in Boeing Alert Service Bulletin 747-25A3588, dated July 19, 2010: Do a general visual inspection of the MEC drip shield to detect cracking and holes; do all applicable repairs; and install the MEC drip shield panel stiffeners and the fiberglass reinforcing overcoat to the MEC drip shield; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-25A3588, dated July 19, 2010. Do all applicable repairs before further flight.

(2) For Group 2 airplanes, as identified in Boeing Alert Service Bulletin 747-25A3588, dated July 19, 2010: Do a general visual inspection of the MEC drip shield to detect cracking and holes; do all applicable repairs; and install the fiberglass reinforcing overcoat to the MEC drip shield; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-25A3588, dated July 19, 2010. Do all applicable repairs before further flight.

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. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD. Information may be e-mailed to: [e-mail].

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.

Related Information

(i) For more information about this AD, contact Marcia Smith, Aerospace Engineer, Cabin Safety & Environmental Systems Branch, ANM-150S FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone: [phone]; fax: [phone]; e-mail: [e-mail].

(j) For service information identified in this 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.

Issued in Renton, Washington, on February 3, 2011.

Ali Bahrami,

Manager,Transport Airplane Directorate, Aircraft Certification Service.