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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-NM-356-AD] 
          - RIN 2120-AA64 

# 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 EMBRAER Model EMB-120 series airplanes. This proposal would require revising the Airplane Flight Manual (AFM), and either installing hydraulic tube assemblies incorporating a check valve, or visually inspecting the check valve if already installed and corrective action, if necessary. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent the landing gear doors from becoming blocked from opening during application of emergency procedures in the event of a loss of hydraulics. 

# DATES:

Comments must be received by May 17, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-356-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. 

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, Small Airplane Directorate, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia. 

# FOR FURTHER INFORMATION CONTACT:

                        Robert Capezutto, Aerospace Engineer, Systems and Flight Test Branch, ACE-                              ( print page 20389)                            116A, FAA, Small Airplane Directorate, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia 30349; telephone (770) 703-6071; fax (770) 703-6097.                     

# 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 notice may be changed in light of the comments received. 

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 notice must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 99-NM-356-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. 99-NM-356-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 EMB-120 series airplanes. The DAC advises that, in the event of the loss of the green hydraulic system pressure, if the present Airplane Flight Manual (AFM) “Free-Fall” operational procedure is not followed, there is a possibility that the landing gear doors may not open. Investigation revealed that blockage of the doors may occur due to the energizing of the landing gear door selector valve in the absence of hydraulic fluid. (The spool valve may not shift completely and may result in trapped fluid in the door's closure line.) This condition, if not corrected, could result in the landing gear doors becoming blocked from opening during application of emergency procedures in the event of a loss of hydraulics. 

## FAA's Determination 

In light of this information, the FAA finds that certain cautionary statements should be included in the FAA-approved AFM to ensure that correct procedures are followed in the event of a loss of hydraulics. The FAA has determined that the procedures currently may not be defined adequately in the AFM for these airplanes. 

## Explanation of Relevant Service Information 

Empresa Brasileira de Aeronautica S.A. (EMBRAER) has issued Service Bulletin 120-32-0077, Change 02, dated December 23, 1997, which describes procedures for installation of hydraulic tube assemblies incorporating a check valve. For airplanes already equipped with those check valves, the service bulletin describes procedures for a visual inspection to detect the check valve flow direction, and reorientation of the valve, if installed incorrectly. The DAC classified this service bulletin as mandatory and issued Brazilian airworthiness directive 97-05-03R2, dated March 16, 1998, in order to assure the continued airworthiness of these airplanes in Brazil. The installation of hydraulic tube assemblies incorporating a check valve is intended to modify the hydraulic system to make the landing gear “Free-Fall” system more tolerant to operational variations from AFM procedures. The Brazilian AD also mandates incorporation of an AFM revision of abnormal landing gear extension procedures. 

## 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 an unsafe condition has been identified 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 incorporation of a revision to the “Emergency Procedures” and “Abnormal Procedures” sections of the FAA-approved AFM. This revision includes cautionary statements to ensure that correct procedures are followed in the event of a loss of hydraulics. The AD would also require accomplishment of the actions specified in the service bulletin described previously. 

## Differences Between Proposed Rule and Brazilian Airworthiness Directive 

The proposed AD differs from the parallel Brazilian airworthiness directive. This proposed AD would require the check valve installation within 2,000 flight hours after the effective date of the AD, whereas the original version of the Brazilian airworthiness directive mandated the installation within 400 hours after the effective date of that AD. The 2,000-flight-hour interval generally corresponds to a “C-check” maintenance period for the EMBRAER EMB-120. The FAA finds that a 2,000-flight-hour compliance time provides an adequate level of safety, and will allow operators to accomplish the installation at the next “C-check.” 

The Brazilian airworthiness directive mandates incorporation of a specific revision level for each of five different AFM's. Of these five, only AFM 120/794 is applicable to U.S.-registered airplanes. Thus, the proposed AD would mandate incorporation of Revision 45 to AFM 120/794. 

## Cost Impact 

The FAA estimates that 213 airplanes of U.S. registry would be affected by this proposed AD. 

The FAA estimates that it would take approximately 1 work hour per airplane to incorporate the applicable AFM revision, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AFM revision proposed by this AD on U.S. operators is estimated to be $12,780, or $60 per airplane. 

                    The FAA estimates that it would take approximately 1 work hour per airplane to perform the visual inspection of the check valve, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the inspection proposed by this AD on U.S.                           ( print page 20390)                        operators is estimated to be $60 per airplane.                 

The FAA estimates that it would take approximately 2 work hours per airplane to install the hydraulic tube assemblies incorporating a check valve, and that the average labor rate is $60 per work hour. Required parts would cost approximately $2,021 per airplane. Based on these figures, the cost impact of the installation proposed by this AD on U.S. operators is estimated to be $2,141 per airplane. 

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 AD were not adopted. 

## Regulatory Impact 

The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. 

                    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 

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

**Empresa Brasileira de Aeronautica S.A. (EMBRAER):**                                 Docket 99-NM-356-AD.                             

*Applicability:*                                 Model EMB-120 series airplanes as listed in EMBRAER Service Bulletin 120-32-0077, Change 02, dated December 23, 1997; 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 (d) 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 landing gear doors from becoming blocked from opening during application of emergency procedures in the event of a loss of hydraulics, accomplish the following: 

(a) Within 10 flight hours after the effective date of this AD, revise the “Emergency Procedures” and “Abnormal Procedures” sections of the FAA-approved Airplane Flight Manual (AFM) by inserting into the AFM a copy of EMB-120 AFM 120/794, Revision 45, dated October 14, 1996. 

(b) For airplanes on which the check valve has been installed in accordance with EMBRAER Service Bulletin 120-32-0077, dated February 7, 1997: Within 100 hours after the effective date of this AD, conduct a visual inspection to detect the check valve flow direction in accordance with Service Bulletin 120-32-0077, Change 02, dated December 23, 1997. If the check valve is installed incorrectly, prior to further flight, reinstall the check valve in the proper position in accordance with Change 02 of the service bulletin. 

(c) For airplanes on which the check valve has not been installed in accordance with EMBRAER Service Bulletin 120-32-0077, dated February 7, 1997; or Change 01, dated September 25, 1997; or Change 02, dated December 23, 1997: Within 2,000 flight hours after the effective date of this AD, install hydraulic tube assemblies incorporating a check valve in accordance with Service Bulletin 120-32-0077, Change 01, dated September 25, 1997; or Change 02, dated December 23, 1997. 

## Alternative Methods of Compliance 

(d) 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 Aircraft Certification Office (ACO), FAA, Small Airplane Directorate. 

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 2:**

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 

(e) 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 3:**

The subject of this AD is addressed in Brazilian airworthiness directive 97-05-03R2, dated March 16, 1998.

Issued in Renton, Washington, on April 11, 2000. 

Donald L. Riggin, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 00-9556 Filed 4-14-00; 8:45 am] 

BILLING CODE 4910-13-P