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Proposed Rule

Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-120 Series Airplanes

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

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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 all EMBRAER Model EMB-120 series airplanes. This proposal would require replacing certain existing potentiometers with recently manufactured potentiometers, modifying the flexible couplers that attach the shafts of the potentiometers to the shafts of the primary flight controls, performing repetitive calibration tests of the potentiometers and obtaining Start Printed Page 21108repetitive readouts of the flight data recorder (FDR), and reporting the results to the FAA. This action is necessary to prevent the potentiometers that provide information on the positions of the primary flight controls to the FDR from transmitting noisy signals or becoming improperly calibrated, resulting in the transmission of incomplete or inaccurate data to the FDR. This lack of reliable data could hamper discovery of the unsafe condition which caused an accident or an incident and prevent the FAA from developing and mandating actions to prevent additional incidents or accidents caused by that same unsafe condition.

DATES:

Comments must be received by May 29, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-120-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 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. 2000-NM-120-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 Empresa Brasileira de Aeronautica S.A. (EMBRAER), P.O. Box 343—CEP 12.225, Sao Jose dos Campos—SP, Brazil. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia.

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FOR FURTHER INFORMATION CONTACT:

Rob Capezzuto, Aerospace Engineer, ACE-116A, FAA, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349; telephone (770) 703-6071; fax (770) 703-6097.

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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 2000-NM-120-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. 2000-NM-120-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The Departmento de Aviacao Civil (DAC), which is the airworthiness authority for Brazil, notified the FAA that an unsafe condition may exist on certain EMBRAER Model EMB-120 series airplanes. The DAC advises that screws on flexible couplers that attach the shafts of the primary flight controls to the shafts of potentiometers may become loose. In this case, erroneous data may be transmitted from the primary flight controls—the ailerons, the elevators, and the rudder—to the flight data recorder (FDR). Therefore, the DAC has issued Brazilian airworthiness directive 97-08-01, dated August 29, 1997, requiring application of adhesive to the screws to lock them in place.

In addition, an investigation of the FDR system indicated that these potentiometers were producing noisy signals. EMBRAER, the manufacturer of the airplanes, and Penny & Giles, the manufacturer of the potentiometers, have attributed the noisy signals to an oxide film which forms on the windings of the potentiometers, if the potentiometers are kept in storage for an extended time.

Finally, investigation of various accidents and incidents has revealed that improperly operating potentiometers have prevented the recording of complete and accurate data which, in some cases, has prevented determination of the cause of an incident or accident.

FAA's Determination of Unsafe Condition

This action is necessary to prevent the potentiometers that provide information on the positions of the primary flight controls to the FDR from functioning improperly, resulting in the transmission of incomplete or inaccurate data to the FDR. Improper functioning of the potentiometers does not directly affect the safety of the airplane on which they are located. However, should an airplane with improperly functioning potentiometers also have an unrelated unsafe condition which results in an incident or accident, the data retrieved from the FDR will be incomplete or inaccurate. This lack of reliable data could hamper discovery of the unsafe condition which caused the accident or incident and prevent the FAA from developing and mandating actions to prevent additional incidents or accidents caused by that same unsafe condition. Therefore, the FAA has determined that the proposed action is necessary.

It should be noted that the purpose of this action is not to enhance the safety of the EMB-120, but rather to restore the level of safety provided by the originally approved FDR. Therefore, this AD is the appropriate regulatory vehicle to achieve this purpose.

Explanation of Relevant Service Information

EMBRAER has issued Service Bulletin 120-31-0038, Change 02, dated June 25, 1998, which describes procedures for applying adhesive to the screws of the flexible couplers which attach the shafts of the potentiometers to the shafts of the primary flight controls to prevent them from becoming loose. The DAC classified this service bulletin as mandatory and issued Brazilian Start Printed Page 21109Airworthiness Directive 97-08-01, dated August 29, 1997.

FAA's Conclusions

This airplane model is manufactured in Brazil and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the DAC has kept the FAA informed of the situation described above. The FAA has examined the findings of the DAC, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of Requirements of Proposed Rule

Since improperly functioning potentiometers may prevent discovery of an unsafe condition that is likely to exist or develop on other airplanes of the same type design registered in the United States, the proposed AD would require removing existing potentiometers and replacing them with recently-manufactured potentiometers, and performing repetitive testing of the calibration of the new potentiometers and obtaining repetitive readouts of the FDR. These actions would be required to be accomplished in accordance with the EMBRAER EMB-120 Maintenance Manual or the EMBRAER EMB-120 service bulletin described previously. In addition, the proposed AD would require submission of the results of the calibration tests and the FDR readouts to the FAA.

Differences Between Proposed AD and Brazilian Airworthiness Directive

The Brazilian airworthiness directive requires only the application of adhesive over the threads of the screws of the flexible couplers which attach the shafts of the potentiometers to the shafts of the primary flight controls. The application is to be accomplished by the next “A” check or within the next 400 flight hours after the effective date of the AD, whichever occurs first.

The proposed AD would also require replacing existing potentiometers for the primary flight controls with potentiometers that were recently manufactured, performing repetitive calibration tests of the potentiometers and obtaining repetitive readouts of the FDR, and submitting the results to the FAA. The compliance time proposed for these more extensive requirements is 6 months.

Interim Action

This proposed AD is considered to be interim action. It would require operators to perform calibration tests of potentiometers and to obtain readouts of FDR's at intervals not to exceed 6 months and to submit reports of the results to the FAA for 2 years. The reports will be used to determine whether the proposed corrective actions adequately address the noisy signals, loose couplers, and incorrect calibrations which have been found. If they do not, the FAA may consider further rulemaking.

Cost Impact

The FAA estimates that 250 airplanes of U.S. registry would be affected by this proposed AD and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is as estimated in Table 1.

Table 1.—Estimated Cost Impact of AD

ActionWork hoursCost of parts (in US $)Cost/airplane (in US $)
Replacement of 3 potentiometers1.03,0003,060
Application of adhesive1.0Negligible60
Calibration of potentiometers1.0Negligible60
Readout of FDR33.0Negligible1,980
Totals36.03,0005,160

The cost impact figures discussed above are 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.

Start List of Subjects

List of Subjects in 14 CFR Part 39

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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:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

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[Amended]

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

Empresa Brasileira de Aeronautica S.A. (EMBRAER): Docket 2000-NM-120-AD.

Applicability: All Model EMB-120 series airplanes, certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability Start Printed Page 21110provision, 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 (e) 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 the potentiometers that provide information on the positions of the primary flight controls to the flight data recorder (FDR) from transmitting noisy signals or becoming improperly calibrated, resulting in the transmission of incomplete or inaccurate data to the FDR, accomplish the following:

Replacement of Potentiometers

(a) Within 6 months after the effective date of this AD: Replace potentiometers to the ailerons, elevators, and rudder with potentiometers that have a date of manufacture within 12 months preceding the date of installation, in accordance with Section 31-30-05 of the EMBRAER EMB-120 Maintenance Manual, dated July 17, 1998.

Note 2:

All potentiometers manufactured by Penny & Giles after January 1999 are date stamped.

Modification of Flexible Coupler

(b) After accomplishment of paragraph (a) of this AD but prior to further flight: Apply locktite adhesive over the threads of the screws of the flexible couplers that attach the shafts of the potentiometers to the shafts of the primary flight controls, in accordance with EMBRAER Service Bulletin 120-31-0038, Change 02, dated June 25, 1998.

Calibration Tests and Readouts

(c) After accomplishment of paragraphs (a) and (b) of this AD but prior to further flight: Perform calibration tests of the potentiometers to the ailerons, elevators, and rudder and obtain a readout of the FDR, in accordance with Section 31-30-00 of the EMBRAER EMB-120 Maintenance Manual, dated July 17, 1998. Repeat the calibration tests and obtain readouts at intervals not to exceed 6 months until 2 years after the effective date of this AD.

Reporting Requirement

(d) At the applicable time specified in paragraph (d)(1) or (d)(2) of this AD: Submit a report of the calibration tests of the potentiometers and the readouts of the FDR to the Manager, Atlanta Aircraft Certification Office (ACO), FAA, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349; fax (770) 703-6097. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

(1) For calibration tests and readouts accomplished after the effective date of this AD: Submit the report within 30 days after performing the tests required by paragraph (c) of this AD.

(2) For calibration tests and readouts accomplished prior to the effective date of this AD: Submit the report within 10 days after the effective date of this AD.

Alternative Methods of Compliance

(e) 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, Atlanta ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta ACO.

Note 3:

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

Special Flight Permits

(f) 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.

Note 4:

The subject of this AD is addressed in Brazilian airworthiness directive 97-08-01, dated August 29, 1997.

Start Signature

Issued in Renton, Washington, on April 20, 2001.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 01-10467 Filed 4-26-01; 8:45 am]

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