2010-8249. Airworthiness Directives; The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400F, 747SR, and 747SP 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 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400F, 747SR, and 747SP series airplanes. This proposed AD would require reworking or replacing certain duct assemblies in the environmental control system (ECS). This proposed AD results from reports of duct assemblies in the ECS with burned Boeing Material Specification (BMS) 8-39 polyurethane foam insulation. This proposed AD also results from a report from the airplane manufacturer that airplanes were assembled with duct assemblies in the ECS wrapped with BMS 8-39 polyurethane foam insulation, a material of which the fire retardant properties deteriorate with age. We are proposing this AD to prevent a potential electrical arc from igniting the BMS 8-39 polyurethane foam insulation on the duct assemblies of the ECS, which could propagate a small fire and lead to a larger fire that might spread throughout the airplane through the ECS.

DATES:

We must receive comments on this proposed AD by May 27, 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:

Sue McCormick, 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-2010-0275; Directorate Identifier 2009-NM-231-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 reports of duct assemblies in the environmental control system (ECS) with burned Boeing Material Specification (BMS) 8-39 polyurethane foam insulation on two Model 767-200 series airplanes. The airplane manufacturer has also notified us that certain Model 767-200 and 767-300 series airplanes and certain Model 747 airplanes were assembled with duct assemblies in the ECS wrapped with BMS 8-39 polyurethane foam insulation. The fire-retardant properties of the BMS 8-39 polyurethane foam insulation deteriorate with age. This, along with dust, dirt, and other carbon particulate contamination of the insulation on the ducts, adds an available fuel source for a potential fire. Once ignited, the foam insulation emits noxious smoke, does not self-extinguish, and drips droplets of liquefied polyurethane, which can further propagate a fire. Because the insulation is wrapped around the duct assemblies, which are located throughout the airplane, if the insulation is ignited a fire could potentially travel along the ducts and spread throughout the airplane. This condition, if not corrected, could result in a potential electrical arc igniting the BMS 8-39 polyurethane foam insulation on the duct assemblies of the ECS, which could propagate a small fire and lead to a larger fire that may spread throughout the airplane through the ECS.

Other Relevant Rulemaking

On January 14, 2008, we issued AD 2008-02-16, amendment 39-15346, applicable to certain Model 767-200 and 767-300 series airplanes. That AD requires reworking certain duct assemblies in the ECS. That AD resulted from reports of duct assemblies in the ECS with burned BMS 8-39 polyurethane foam insulation. That AD also resulted from a report from the airplane manufacturer that airplanes were assembled with duct assemblies in the ECS wrapped with BMS 8-39 polyurethane foam insulation, a material of which the fire retardant properties deteriorate with age. We issued that AD to prevent a potential electrical arc from igniting the BMS 8-39 polyurethane foam insulation on the duct assemblies of the ECS, which could propagate a small fire and lead to a larger fire that might spread throughout the airplane through the ECS.

Additionally, on December 14, 2001, we issued AD 2001-26-09, amendment 39-12573 (66 FR 66734, December 27, 2001), applicable to certain Model 767-200 series airplanes. That AD requires a one-time inspection for damage of the water line heater tape where it passes close to the duct assemblies of the air distribution system for the flight compartment. That AD also requires eventual replacement of certain duct assemblies or foam insulation on those duct assemblies with new assemblies or improved foam insulation. That AD was prompted by a report of burned BMS 8-39 polyurethane foam insulation on an air distribution system duct located in the electronics and electrical compartment. The actions required by that AD are intended to prevent ignition of foam insulation on the air distribution ducts, which could result in a fire in the airplane.

We are considering additional rulemaking for Model 737-100, -200, -200C, and -300 series airplanes, which have been determined to be subject to the same unsafe condition.

Relevant Service Information

We have reviewed Boeing Service Bulletin 747-21A2421, Revision 2, dated December 19, 2006. This service bulletin describes procedures for reworking the affected duct assemblies in approximately 44 locations within the ECS systems. The affected duct assemblies vary depending on airplane configuration. These are some examples of affected ECS systems:

• Air conditioning, flight deck
• Duct installation, conditioned air
• Duct installation, air distribution system
• Duct installation, individual air system
• Anemostat installation, air distribution system
• Humidifier duct installation
• Heat exchanger installation, air conditioning system
• Recirculation fan installation, flight deck

We have also reviewed Boeing Service Bulletin 747-21A2422, Revision 2, dated November 16, 2006. This service bulletin describes procedures for reworking or replacing the single duct assembly in the forward lower cargo bay. The rework includes removing the BMS 8-39 polyurethane foam insulation and replacing it with BMS 8-300 polyimide foam insulation that meets flammability criteria of Section 25.856 (“Fire Protection: Thermal/Acoustic Insulation Materials”) of the Federal Aviation Regulations (14 CFR 25.856(a)).

These service bulletins also describe procedures for part-marking reworked duct assemblies with new part numbers.

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, except as discussed under “Differences Between the Proposed AD and the Service Bulletins.”

Differences Between the Proposed AD and the Service Bulletins

Boeing Service Bulletin 747-21A2421, Revision 2, dated December 19, 2006, recommends reworking the affected duct assemblies “during the next heavy maintenance visit, not to exceed 30,000 flight-hours” from the date on that service bulletin. Boeing Service Bulletin 747-21A2422, Revision 2, dated November 16, 2006, does not recommend any compliance time for reworking or replacing the affected duct assemblies. This proposed AD would require operators to rework or replace the affected duct assemblies within 72 months after the effective date of the AD. In developing the compliance time for this action, we considered the degree of urgency associated with addressing the subject unsafe condition. We also considered the availability of required parts and the practical aspect of reworking or replacing the affected duct assemblies within an interval that parallels normal scheduled maintenance for most affected operators. We have determined that the average utilization of the Model 747 fleet is approximately 5,000 flight hours each year. Therefore, we have determined that 72 months is equivalent to the recommended compliance time of 30,000 flight hours and it represents an appropriate interval in which an ample number of required parts will be available to modify the affected fleet without adversely affecting the safety of these airplanes. This difference has been coordinated with Boeing.

Costs of Compliance

There are about 558 airplanes of the affected design in the worldwide fleet. The average labor rate is $85 per work-hour. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Parts cost, per airplane	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Duct assembly rework, specified in Boeing Service Bulletin 747-21A2421	8 per duct (average of 130 ducts per airplane)	$12,305 (average)	$100,705 (average)	185	$18,630,425.
Duct assembly rework or replacement, specified in Boeing Service Bulletin 747-21A2422	1 per duct (1 duct per airplane)	The manufacturer states that it will supply required parts to the operators at no cost.	$85	Up to 168	Up to $14,280.

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-2010-0275; Directorate Identifier 2009-NM-231-AD.

Comments Due Date

(a) We must receive comments by May 27, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to the airplanes specified in paragraphs (c)(1) and (c)(2) of this AD, certificated in any category.

(1) The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP series airplanes identified in Boeing Service Bulletin 747-21A2421, Revision 2, dated December 19, 2006.

(2) The Boeing Company Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747-400F, 747SR, and 747SP series airplanes identified in Boeing Service Bulletin 747-21A2422, Revision 2, dated November 16, 2006.

Subject

(d) Air Transport Association (ATA) of America Code 21: Air conditioning.

Unsafe Condition

(e) This AD results from reports of duct assemblies in the environmental control system (ECS) with burned Boeing Material Specification (BMS) 8-39 polyurethane foam insulation. This AD also results from a report from the airplane manufacturer that airplanes were assembled with duct assemblies in the ECS wrapped with BMS 8-39 polyurethane foam insulation, a material of which the fire retardant properties deteriorate with age. We are issuing this AD to prevent a potential electrical arc from igniting the BMS 8-39 polyurethane foam insulation on the duct assemblies of the ECS, which could propagate a small fire and lead to a larger fire that could spread throughout the airplane through the ECS.

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.

ECS Duct Assembly Rework or Replacement

(g) Within 72 months after the effective date of this AD, rework or replace the applicable duct assemblies in the ECS specified in and in accordance with the Accomplishment Instructions and Appendices A through F of Boeing Service Bulletin 747-21A2421, Revision 2, dated December 19, 2006 (for Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP series airplanes); and the Accomplishment Instructions and Appendices A through C of Boeing Service Bulletin 747-21A2422, Revision 2, dated November 16, 2006 (for Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747-400F, 747SR, and 747SP series airplanes).

Parts Installation

(h) As of the effective date of this AD, no person may install an ECS duct assembly with BMS 8-39 polyurethane foam insulation on any airplane.

Alternative Methods of Compliance (AMOCs)

(i)(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: Sue McCormick, 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]. Or, e-mail information 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 April 1, 2010.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.