E9-16943. Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, -900 and -900ER Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.

SUMMARY:

We are revising an earlier proposed airworthiness directive (AD) for all Boeing Model 737-600, -700, -700C, -800, -900 and -900ER series airplanes. That supplemental NPRM would have required a one-time inspection to determine the part numbers of the aero/fire seals of the blocker doors on the thrust reverser torque boxes on the engines, and replacing affected aero/fire seals with new improved aero/fire seals. This action resulted from a report that the top 3 inches of the aero/fire seals of the blocker doors on the thrust reverser torque boxes are not fireproof. This second supplemental NPRM revises the first supplemental NPRM by changing the compliance time for the replacement. We are proposing this second supplemental NPRM to prevent a fire in the fan compartment (a fire zone) from migrating through the seal to a flammable fluid in the thrust reverser actuator compartment (a flammable fluid leakage zone), which could result in an uncontrolled fire.

DATES:

We must receive comments on this supplemental NPRM by August 10, 2009.

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, P.O. Box 3707, Seattle, Washington 98124-2207; telephone [phone]; 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 or 425-227-1152.

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:

Samuel Spitzer, Aerospace Engineer, Propulsion Branch, ANM-140S, 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-2006-25001; Directorate Identifier 2006-NM-079-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 issued a notice of proposed rulemaking (NPRM) (the “first supplemental NPRM”) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. The first supplemental NPRM was published in the Federal Register on September 3, 2008 (73 FR 51382). The first supplemental NPRM proposed to require a one-time inspection to determine the part numbers of the aero/fire seals of the blocker doors on the thrust reverser torque boxes on the engines, and replacing affected aero/fire seals with new improved aero/fire seals.

Actions Since First Supplemental NPRM Was Issued

Since we issued the first supplemental NPRM, we have determined that it is necessary to change the compliance time for the replacement action in paragraph (h) from “within 60 months or 8,200 flight cycles after the effective date of this AD,” to “prior to further flight after doing the actions specified in paragraph (g) of this AD.” Our intent in the first supplemental NPRM was to require replacement of an affected aero/fire seal before further flight after identification.

Comments

We gave the public the opportunity to participate in developing this AD. We considered the comment received on the first supplemental NPRM. Boeing supports the NPRM.

Additional Changes to Supplemental NPRM

For clarification purposes, we have revised paragraph (h) of this second supplemental NPRM to change “as having an affected P/N” to “to have a non-fireproof seal.”

We have also added new paragraph (d) in this supplemental NPRM to identify the Air Transport Association of America code.

FAA's Determination and Proposed Requirements of the Second Supplemental NPRM

We are proposing this second supplemental NPRM because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design. Certain changes described above expand the scope of the first supplemental NPRM. As a result, we have determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this second supplemental NPRM.

Costs of Compliance

There are about 2,442 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 for part number	1	$80	None	$80	803	$64,240

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:

Boeing: Docket No. FAA-2006-25001; Directorate Identifier 2006-NM-079-AD.

Comments Due Date

(a) We must receive comments by August 10, 2009.

Affected ADs

(b) None.

Applicability

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

Subject

(d) Air Transport Association (ATA) of America Code 78: Engine exhaust.

Unsafe Condition

(e) This AD results from a report that the top 3 inches of the aero/fire seals of the blocker doors on the thrust reverser torque boxes are not fireproof. The Federal Aviation Administration is issuing this AD to prevent a fire in the fan compartment (a fire zone) from migrating through the seal to a flammable fluid in the thrust reverser actuator compartment (a flammable fluid leakage zone), which could result in an uncontrolled fire.

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.

Inspection To Determine Part Number (P/N)

(g) Within 60 months or 8,200 flight cycles after the effective date of this AD, whichever occurs first: Perform a one-time detailed inspection to determine the color of the aero/fire seals of the blocker doors on the thrust reverser torque boxes on the engines. For any aero/fire seal having a completely grey color (which is the color of seals with P/N 315A2245-1 or 315A2245-2), with no red at the upper end of the seal, do the actions specified in paragraph (h) of this AD. For any aero/fire seal having a red color at the upper end of the seal (which indicates a different part number), no further action is required by this AD. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number of the correct aero/fire seals (P/N 315A2245-7 or -8) can be conclusively determined to be installed from that review.

Note 1:

For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirrors, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”

Replace the Aero/Fire Seals

(h) For any aero/fire seal identified during the inspection/records check in paragraph (g) of this AD to have a non-fireproof seal: Prior to further flight after doing the actions specified in paragraph (g) of this AD, replace the aero/fire seals of the blocker doors on the thrust reverser torque boxes on the engines with new, improved aero/fire seals in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-78-1074, Revision 1, dated September 15, 2005.

Credit for Actions Done Using Previous Service Information

(i) Replacements done before the effective date of this AD in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-78-1074, dated April 7, 2005, are acceptable for compliance with the requirements of paragraph (h) of this AD.

Alternative Methods of Compliance (AMOCs)

(j)(1) The Manager, Seattle Aircraft Certification Office, 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: Samuel Spitzer, Aerospace Engineer, Propulsion Branch, ANM-140S, 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 July 6, 2009.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.