Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes Equipped With Honeywell Start Converter Units

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes equipped with certain Honeywell start converter units (SCU). This proposal would require replacement of the SCU of the auxiliary power unit (APU) located in the electrical and electronics (E/E) compartment with a new, improved SCU. This action is necessary to prevent overheating of the electrical connector of the SCU, which could create an ignition source and possible fire in the E/E compartment and cause damage to certain electrical wire bundles on the E2-2 shelf. Such damage could result in loss of power from the APU generator, failure of electrically powered airplane systems, and consequent reduction in the ability of the flight crew to control the airplane in certain adverse operating conditions. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by September 23, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-291-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-291-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronics files must be formatted in Microsoft Word 97 for Windows or ASCII text.

Information pertaining to this amendment may be obtained from or examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Stephen S. Oshiro, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2793; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received. Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-291-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-291-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received several reports of failure of the auxiliary power unit (APU) to start or to generate electrical power after start-up or during APU operation on certain Boeing Model 737-700 and −800 series airplanes. During these APU failures, there was an odor of smoke detected by personnel on the flight deck. Investigation revealed signs of heat damage to the Aeronautical Radio, Incorporated (ARINC), connector of the APU start converter unit (SCU). (The ARINC connector is located on the back panel of the SCU housing and provides for electrical connection between the SCU and the APU generator.) The heat damage spread to the mating connector and adjacent wire bundles located on the E2-2 shelf of the electrical and electronics (E/E) compartment. Further investigation revealed that the damage was caused by a short circuit of certain capacitors that are part of the electromagnetic interference filter inside the ARINC connector. Such conditions, if not corrected, could result in overheating of the electrical connector of the SCU, which could create an ignition source and possible fire in the E/E compartment and cause damage to certain electrical wire bundles on the E2-2 shelf. Such damage could result in loss of power from the APU generator, failure of electrically powered airplane systems, and consequent reduction in the ability of the flight crew to control the airplane in certain adverse operating conditions.

The SCU of the APU is the same on certain Model 737-600 and −900 series airplanes as it is on certain Model 737-700, −700C, and −800 series airplanes. Therefore, all of these airplanes may be subject to the same unsafe condition described above.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD is being issued to prevent overheating of the electrical connector of the SCU, which could create an ignition source and possible fire in the E/E compartment and cause damage to certain electrical wire bundles on the E2-2 shelf. Such damage could result in loss of power from the APU generator, failure of electrically powered airplane systems, and consequent reduction in the ability of the flight crew to control the airplane in certain adverse operating conditions. The proposed AD would require replacement of certain SCUs with new, improved SCUs. The SCUs would be required to be replaced according to Boeing 737-600/700/800/900 Airplane Maintenance Manual (AMM)(the AMM includes procedures for Model 737-700C series airplanes).

Cost Impact

There are approximately 901 airplanes of the affected design in the worldwide fleet. The FAA estimates that 441 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 4 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Required parts would be provided by the parts manufacturer at no cost to operators. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $105,840, or $240 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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.