E6-12302. Airworthiness Directives; Boeing Model 747-400 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Boeing Model 747-400 series airplanes. The existing AD currently requires replacement of the decompression panels that are located in the smoke barrier between the passenger and main deck cargo compartment with new panels of an improved design. This proposed AD would require modification of the decompression panels on the smoke barrier in the main deck cargo compartment or replacement of the smoke barrier with an improved smoke barrier, as applicable. This proposed AD would also require repetitive inspections of the decompression (vent) panels on the smoke barrier and corrective actions if necessary. This proposed AD also adds airplanes to the applicability. This proposed AD results from reports of decompression panels on the smoke barrier opening in flight and on the ground without a decompression event. We are proposing this AD to prevent inadvertent opening or tearing of decompression panels, which could result in degraded cargo fire detection and suppression capability, smoke penetration into an occupied compartment, and an uncontrolled cargo fire, if a fire occurs in the main deck cargo compartment.

DATES:

We must receive comments on this proposed AD by September 15, 2006.

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 service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Susan Letcher, 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 “Docket No. FAA-2006-25470; Directorate Identifier 2006-NM-090-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 the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or 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

On November 14, 1996, we issued AD 96-24-03, amendment 39-9829 (61 FR 59319, November 22, 1996), for certain Boeing Model 747-400 “combi” series airplanes. That AD requires replacing the decompression panels located in the smoke barrier between the passenger and main deck cargo compartments with new panels of an improved design. That AD resulted from reports indicating that normal pressurization cycles are causing premature tearing or opening of these decompression panels. We issued that AD to prevent increased airflow in the cargo compartment caused by the tearing or opening of these panels; this condition, if not corrected, could result in delayed fire detection and reduced effectiveness of the cargo compartment fire suppression system.

Actions Since Existing AD Was Issued

Since we issued AD 96-24-03, operators have reported that decompression panels on the smoke barrier in the main deck cargo compartment are opening in flight and on the ground without a decompression event, on Boeing Model 747-400 series airplanes. We have determined that the modification required by AD 96-24-03 has not been effective in preventing inadvertent opening or tearing of decompression panels on the smoke barrier. This condition, if not corrected, could result in degraded cargo fire detection and suppression capability, smoke penetration into an occupied compartment, and an uncontrolled cargo fire, if a fire occurs in the main deck cargo compartment.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-25A3353, dated December 9, 2004. The service bulletin describes procedures for either modifying the decompression panels on the smoke barrier in the main deck cargo compartment, or replacing the smoke barrier with an improved smoke barrier, depending on the airplane configuration. The modification, if required, includes the following actions:

• Replacing the existing decompression panels with new, improved decompression (vent) panels.
• Replacing the forward frames with new, improved forward frame assemblies.
• For certain airplanes, replacing spring clips with new spring clips.
• For certain airplanes, replacing snap brackets with new spring clips and removing chain assemblies.
• Installing aft frame angles.

The service bulletin also describes procedures for inspecting the decompression (vent) panels of the smoke barrier for changes from their installed condition and accomplishing corrective actions as necessary. The corrective actions include restoring vent panels to their installed condition and replacing any damaged components with new components.

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 develop on other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 96-24-03. The proposed AD would require accomplishing the actions specified in the service bulletin described previously.

Clarification of Inspection Terminology

The “inspection” specified in the service bulletin is referred to as a “general visual inspection” in the proposed AD. We have included the definition for a general visual inspection in a note in the proposed AD.

Explanation of Change to Applicability

We have revised the applicability of the proposed AD to identify model designations as published in the most recent type certificate data sheet for the affected models. The proposed AD does not use the term, “combi” airplanes. We have also added airplanes to the applicability of this proposed AD.

Costs of Compliance

There are about 63 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs, at an average labor rate of $80 per hour, for U.S. operators to comply with the proposed AD. The estimated work hours and cost of parts for the proposed modification in the table below depends on the configuration of an airplane.

Estimated Costs

Action	Work hours	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Modification (new proposed action)	16-17	$12,064-$15,362	$13,344-$16,722	2	$26,688-$33,444
Replacement (new proposed action)	4	48,647	48,967	2	97,934
Inspection (new proposed action)	2	None	160	2	320

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 removing amendment 39-9829 (61 FR 59319, November 22, 1996) and adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-25470; Directorate Identifier 2006-NM-090-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by September 15, 2006.

Affected ADs

(b) This AD supersedes AD 96-24-03.

Applicability

(c) This AD applies to Boeing Model 747-400 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 747-25A3353, dated December 9, 2004.

Unsafe Condition

(d) This AD results from reports of decompression panels on the smoke barrier opening in flight and on the ground without a decompression event. We are issuing this AD to prevent inadvertent opening or tearing of decompression panels, which could result in degraded cargo fire detection and suppression capability, smoke penetration into an occupied compartment, and an uncontrolled cargo fire, if a fire occurs in the main deck 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.

New Requirements of This AD

Modification or Replacement, as Applicable

(f) Within 48 months after the effective date of this AD: Modify the decompression panels on the smoke barrier or replace the smoke barrier with an improved smoke barrier, by accomplishing all of the actions specified in Work Package 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-25A3353, dated December 9, 2004, as applicable.

Repetitive Inspection

(g) Within 20 months or 6,000 flight hours after accomplishing paragraph (f) of this AD, whichever occurs first: Do a general visual inspection of the decompression (vent) panels on the smoke barrier for any changes from their installed condition, and do all corrective actions before further flight after the inspection, by accomplishing all of the actions specified in Work Package 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-25A3353, dated December 9, 2004, as applicable. Repeat the inspection thereafter at intervals not to exceed 20 months or 6,000 flight hours, whichever occurs first.

Note 1:

For the purposes of this AD, a general visual inspection is: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Seattle Aircraft Certification Office, Transport Airplane Directorate, 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.

Issued in Renton, Washington, on July 21, 2006.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.