E8-25990. Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 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 737-600, -700, -700C, -800, and -900 series airplanes. The existing AD currently requires replacing brackets that hold the P5 panel to the airplane structure, the standby compass bracket assembly, the generator drive and standby power module, and the air conditioning module. The existing AD also currently requires, among other actions, inspecting for wire length and for damage of the connectors and the wire bundles, and doing applicable corrective actions if necessary. This proposed AD would require an additional operational test of the P5-14 panel. This proposed AD results from a report of an electrical burning smell in the flight compartment. We are proposing this AD to prevent wire bundles from contacting the overhead dripshield panel and modules in the P5 overhead panel, which could result in electrical arcing and shorting of the electrical connector and consequent loss of several critical systems essential for safe flight; and to ensure proper operation of the passenger oxygen system. If an improperly functioning passenger oxygen system goes undetected, the passenger oxygen mask could fail to deploy and result in possible incapacitation of passengers during a depressurization event.

DATES:

We must receive comments on this proposed AD by December 15, 2008.

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 AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

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:

Binh Tran, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, 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-2008-1143; Directorate Identifier 2008-NM-136-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

On May 8, 2006, we issued AD 2006-10-17, amendment 39-14601 (71 FR 28766, May 18, 2006), for certain Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. That AD requires replacing brackets that hold the P5 panel to the airplane structure, the standby compass bracket assembly, the generator drive and standby power module, and the air conditioning module. That AD also requires, among other actions, inspecting for wire length and for damage of the connectors and the wire bundles, and doing applicable corrective actions if necessary. That AD resulted from an electrical burning smell in the flight compartment. We issued that AD to prevent wire bundles from contacting the overhead dripshield panel and modules in the P5 overhead panel, which could result in electrical arcing and shorting of the electrical connector and consequent loss of several critical systems essential for safe flight.

Actions Since Existing AD Was Issued

Since we issued AD 2006-10-17, a review of an operator's compliance document revealed that an operational test of only the crew oxygen pressure indication in the P5-14 panel had been done (the passenger oxygen system was not tested). The operator had done the operational test in accordance with Boeing Service Bulletin 737-24A1141, Revision 2, dated December 1, 2005 (referred to as an appropriate source of service information for accomplishing certain actions required by AD 2006-10-17). Paragraph 3.B., “Work Instructions,” paragraphs 92 and 93, note (b), of the service bulletin refers to Chapter 35-12-00/501 of 737-600/700/800/900 Airplane Maintenance Manual (AMM) as the appropriate source of service information for accomplishing the operational test on both the passenger oxygen system and crew oxygen pressure indication. However, Chapter 35-12-00/501 describes procedures for an operational test of only the crew oxygen pressure indication. Chapter 35-22-00/501 describes procedures for an operational test of the passenger oxygen system.

If an operational test of the passenger oxygen system in the P5-14 panel is not done, an improperly functioning passenger oxygen system could go undetected and result in the failure of the passenger oxygen mask to deploy and possible incapacitation of passengers during a depressurization event.

Relevant Service Information

We have reviewed Boeing Service Bulletin 737-24A1141, Revision 3, dated February 20, 2008. The inspections, replacements, wiring changes, and corrective actions specified in Revision 3 of service bulletin are essentially identical to those specified in Revision 2 of the service bulletin. Revision 3 clarifies the Accomplishment Instructions, changes airplane operators (no additional airplanes have been added to the Effectivity of the service bulletin), and corrects typographical errors, including the incorrect AMM reference described previously. 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 2006-10-17 and would retain the requirements of the existing AD. This proposed AD would also require doing an additional operational test of the P5-14 panel and accomplishing the actions specified in the service information described previously.

Costs of Compliance

There are about 740 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 333 airplanes of U.S. registry.

For all airplanes, the required inspection, replacements, and wiring change that are required by AD 2006-10-17 and retained in this proposed AD take about 16 or 18 work hours per airplane (depending on airplane configuration), at an average labor rate of $80 per work hour. Required parts would cost about $10,231 or $11,139 per airplane (depending on the kit). Based on these figures, the estimated cost of the replacements and inspections required by this proposed AD for U.S. operators is between $3,833,163 and $4,188,807, or between $11,511 and $12,579 per airplane.

For certain airplanes, the modification of the generator drive and standby power module assembly that is required by AD 2006-10-17 and retained in this proposed AD takes about 2 work hours per airplane, at an average labor rate of $80 per work hour. The airplane manufacturer states that it will supply required parts to operators at no cost. Based on these figures, the estimated cost of this modification proposed by this AD is $160 per airplane.

For certain other airplanes, the modification of the air conditioning module assembly that is required by AD 2006-10-17 and retained in this proposed AD takes about 1 work hour per airplane, at an average labor rate of $80 per work hour. The airplane manufacturer states that it will supply required parts to operators at no cost. Based on these figures, the estimated cost of this modification proposed by this AD is $80 per airplane.

For certain airplanes, the new proposed action would take about 21 or 23 work hours per airplane depending on the airplane configuration, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the new actions specified in this proposed AD for U.S. operators is $1,680 or $1,840 per airplane, depending on the airplane configuration.

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 39-14601 (71 FR 28766, May 18, 2006) and adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2008-1143; Directorate Identifier 2008-NM-136-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by December 15, 2008.

Affected ADs

(b) This AD supersedes AD 2006-10-17.

Applicability

(c) This AD applies to Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category; as identified in Boeing Service Bulletin 737-24A1141, Revision 3, dated February 20, 2008.

Unsafe Condition

(d) This AD results from a report of an electrical burning smell in the flight compartment. We are issuing this AD to prevent wire bundles from contacting the overhead dripshield panel and modules in the P5 overhead panel, which could result in electrical arcing and shorting of the electrical connector and consequent loss of several critical systems essential for safe flight; and to ensure proper operation of the passenger oxygen system. If an improperly functioning passenger oxygen system goes undetected, the passenger oxygen mask could fail to deploy and result in possible incapacitation of passengers during a depressurization event.

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.

Requirements of AD 2006-10-17

Inspection/Replacements/Wiring Changes/Corrective Actions

(f) Within 36 months after June 22, 2006 (the effective date of AD 2006-10-17), do the actions in paragraphs (f)(1) through (f)(5) of this AD by accomplishing all the applicable actions specified in the Accomplishment Instructions of Boeing Service Bulletin 737-24A1141, Revision 2, dated December 1, 2005, except as provided by paragraph (i) of this AD. Any applicable corrective actions must be done before further flight.

(1) Replace the five brackets that hold the P5 panel to the airplane structure with new brackets;

(2) Do a general visual inspection for wire length and damage of the connectors and the wire bundles, and applicable corrective actions;

(3) Make wiring changes;

(4) Replace the standby compass bracket assembly with a new assembly; and

(5) Replace the stud assemblies with new assemblies.

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.”

(g) Actions done before June 22, 2006, in accordance with Boeing Alert Service Bulletin 737-24A1141, Revision 1, dated December 23, 2004, are acceptable for compliance with the requirements of paragraph (f) of this AD.

Concurrent Requirements

(h) Before or concurrently with the requirements of paragraph (f) of this AD, do the applicable action specified in Table 1 of this AD.

Table 1—Concurrent Requirements

For airplanes identified in Boeing Component Service Bulletin—	Action—
(1) 233A3205-24-01, dated July 26, 2001	Modify the generator drive and standby power module assembly in accordance with the Accomplishment Instructions of the Service Bulletin.
(2) 69-37319-21-02, Revision 1, dated August 30, 2001	Modify the air conditioning module assembly in accordance with the Accomplishment Instructions of the Service Bulletin.

New Actions Required by This AD

New Service Bulletin Revision

(i) As of the effective date of this AD, use only the Accomplishment Instructions of Boeing Service Bulletin 737-24A1141, Revision 3, dated February 20, 2008, to do all the applicable actions required by paragraph (f) of this AD.

Additional Operational Test

(j) For airplanes on which the actions required by paragraph (f) of this AD have been done in accordance with Boeing Service Bulletin 737-24A1141, Revision 2, dated December 1, 2005, before the effective date of this AD: Within 12 months after the effective date of this AD, do an operational test of the P5-14 panel in accordance with paragraphs 3.B.92. and 3.B.93., as applicable, of the Accomplishment Instructions of Boeing Service Bulletin 737-24A1141, Revision 3, dated February 20, 2008.

Alternative Methods of Compliance (AMOCs)

(k)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Binh Tran, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]; has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

(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 appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(3) AMOCs approved previously in accordance with AD 2006-10-17 are approved as AMOCs for the corresponding provisions of this AD.

Issued in Renton, Washington, on October 20, 2008.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.