02-30348. Airworthiness Directives; Boeing Model 737-400, -500, -600, -700, and -800 Series Airplanes

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 737-400, -500, -600, -700, and -800 series airplanes. This proposal would require modification of the wiring to the windshield wiper motors in the flight compartment and nose wheel well areas. For certain airplanes, this proposal also provides for optional replacement of the windshield wiper motor/converters in the flight compartment. This action is necessary to prevent a reduction in flight crew visibility due to stalled wiper motors during heavy precipitation and a period of substantial crew workload, which could result in damage to the airplane structure and injury to flight crew, passengers, or ground personnel during final approach for landing. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by January 16, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-326-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 [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-326-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Don Eiford, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

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-326-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-326-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports of windshield motors stalling during flight on certain Boeing Model 737 series airplanes. In a number of incidents, the windshield wipers of both the pilot and first officer stalled. Stalling of the wiper motors was attributed to inadequate torque, caused by insufficient electrical current to the motor due to undersized wires to the windshield wiper motors. In addition, there have been reports of loss of windshield wiper blade load, which can lead to flutter of the windshield wiper arm and inability to clear the windshield. Such conditions could result in a reduction in flight crew visibility during heavy precipitation and a period of substantial crew workload, and consequent damage to the airplane structure and injury to flight crew, passengers, or ground personnel during final approach for landing.

Explanation of Relevant Service Information

We have reviewed and approved Boeing Alert Service Bulletins 737-30A1049, dated June 1, 2000 (for Model 737-600, -700, and -800 series airplanes); and 737-30A1052, dated October 12, 2000 (for Model 737-400 and -500 series airplanes). The service bulletins describe procedures for modification of the wiring to the windshield wiper motor in the flight compartment and nose wheel well areas, as applicable. The modification specified in service bulletin 737-30A1049 includes changing wire bundles W0018, W2108, W2208, W2653, and W5506 in the flight compartment, and W2175 and W5506 above the nose wheel well area; reducing the blade force of the windshield wipers to between 3.5 and 4.5 pounds; and doing an operational test of the windshield wiper system. The modification specified in Service Bulletin 737-30A1052 includes changing wire bundles W0018, W0036, W0504, and W0544 in the flight compartment; reducing the blade force of the windshield wipers to between 3.5 and 4.5 pounds; and doing an operational test of the windshield wiper system.

Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition.

We also have reviewed and approved Boeing Service Bulletin 737-30-1054, dated May 9, 2002 (for Model 737-600, -700, -700C, -800, and -900 series airplanes). The service bulletin describes procedures for replacing the windshield wiper motor/converters in the flight compartment; increasing the blade force of the windshield wipers to between 6.5 and 7.5 pounds; and doing an operational test of the windshield wiper system. Replacement of the motor/converters will support an increase in blade load, which will eliminate the flutter of the windshield wiper arms. The service bulletin recommends prior or concurrent accomplishment of Service Bulletin 737-30A1049.

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 would require modification of the wiring to the windshield wiper motors in the flight compartment and nose wheel well areas. For certain airplanes, this proposal also provides for optional replacement of the windshield wiper motor/converters in the flight compartment. The modification would be required to be accomplished in accordance with Service Bulletins 737-30A1049, and 737-30A1052, as applicable, except as discussed below.

Differences Between Proposed AD and Service Information

The Boeing service bulletins listed below differ from the proposed AD in the compliance times specified for accomplishment of the proposed modification.

• 737-30A1052 recommends that the modification of the wiring to the windshield wiper motors be done as soon as manpower and facilities are available.
• 737-30A1049 recommends that the modification of the left-side wiring be done within 90 days of receipt of the service bulletin, and the modification of the right-side wiring at the next 5,000-hour maintenance interval.

We find that we must ensure that the necessary modification is completed in a timely manner. Therefore, this proposed AD would require modification of the windshield wiper motors within 18 months after the effective date of this AD.

Cost Impact

There are approximately 483 airplanes of the affected design in the worldwide fleet. The FAA estimates that 162 Model 737-600, -700, and -800 series airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 15 work hours per airplane to accomplish the proposed wiring modification, at an average labor rate of $60 per work hour. Required parts would be provided by the manufacturer at no cost to operators. Based on these figures, the cost impact of the modification proposed by this AD on U.S. operators is estimated to be $145,800, or $900 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.

Should an operator elect to do the replacement of the wiper motor/converters, it would take approximately 3 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Parts cost would be minimal. Based on these figures, the cost impact of the replacement proposed by this AD is estimated to be $180 per airplane.

Currently, there are no affected Model 737-400 or -500 series airplanes on the U.S. Register. However, should an airplane be imported and placed on the U.S. Register in the future, it would require approximately 20 work hours to accomplish the proposed modification, at an average labor rate of $60 per work hour. Required parts would be provided by the manufacturer at no cost to operators. Based on these figures, the cost impact of this proposed modification would be $1,200 per airplane.

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

§ 39.13

[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Boeing: Docket 2001-NM-326-AD.

Applicability: Model 737-400 and -500 series airplanes as listed in Boeing Alert Service Bulletin 737-30A1052, dated October 12, 2000; and Model 737-600, -700, and -800 series airplanes as listed in Boeing Alert Service Bulletin 737-30A1049, dated June 1, 2000; certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent a reduction in flight crew visibility due to stalled wiper motors during heavy precipitation and a period of substantial crew workload, which could result in damage to the airplane structure and injury to flight crew, passengers, or ground personnel during final approach for landing; accomplish the following:

Modification

(a) For all airplanes, within 18 months after the effective date of this AD: Modify the wiring to the left and right windshield wiper motors in the flight compartment and nose wheel well areas, as applicable (including changing certain wire bundles, reducing the windshield wiper blade force to between 3.5 and 4.5 pounds, and doing an operational test of the windshield wiper system), per Boeing Alert Service Bulletin 737-30A1052, dated October 12, 2000 (for Model 737-400 and -500 series airplanes); or Boeing Alert Service Bulletin 737-30A1049, dated June 1, 2000 (for Model 737-600, -700, and -800 series airplanes); as applicable.

Optional Replacement

(b) For Model 737-600, -700, and -800 series airplanes: Replace the left and right windshield wiper motor/converters in the flight compartment (including increasing the blade force of the windshield wipers to between 6.5 and 7.5 pounds; and doing an operational test of the windshield wiper system), per Boeing Service Bulletin 737-30-1054, dated May 9, 2002. Paragraph (a) of this AD must be done prior to or concurrent with this paragraph. Replacement of the motor/converters will support an increase in blade load, which will eliminate the flutter of the windshield wiper arms.

Alternative Methods of Compliance

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permit

(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on November 20, 2002.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.