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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. 99-SW-70-AD; Amendment 39-11690; AD 2000-08-04] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration, DOT. 

# ACTION:

Final rule; request for comments. 

# SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to Robinson Helicopter Company (RHC) Model R44 helicopters. This action requires replacing certain serial number (S/N) sprag clutches with an airworthy sprag clutch as specified in this AD. This amendment is prompted by several reports of sprag clutch failures. The actions specified by this AD are intended to prevent a sprag clutch failure, loss of main rotor RPM during autorotation, and subsequent loss of control of the helicopter. 

# DATES:

Effective May 4, 2000. Comments for inclusion in the Rules Docket must be received on or before June 19, 2000. 

# ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 99-SW-70-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. 

# FOR FURTHER INFORMATION CONTACT:

Elizabeth Bumann, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Blvd., Lakewood, California 90712-4137, telephone (562) 627-5265; fax (562) 627-5210. 

# SUPPLEMENTARY INFORMATION:

On April 5, 1999, the FAA issued AD 99-07-18, Amendment 39-11127 (64 FR 17964, April 13, 1999), to require inserting a Special Pilot Caution into the Rotorcraft Flight Manual (RFM) to alert pilots of the potential for the sprag clutch failing to overrun during autorotation maneuvers. The Special Pilot Caution was an interim measure until permanent corrective action was developed by the manufacturer. The FAA now believes that the affected sprag clutches need to be replaced within 30 days or 50 hours time-in-service (TIS), whichever occurs first. Since the sprag clutch is such a critical component of the rotor drive system, this AD requires replacing sprag clutch part number (P/N) C188-3, S/N 0003 through 0505, inclusive, with sprag clutch, P/N C188-3, S/N 0506 and higher. This amendment is prompted by several reports of clutch assemblies, including one from wreckage of an accident, with cracked or fractured sprag ends. The actions specified by this AD are intended to prevent a sprag clutch failure, loss of main rotor RPM during autorotation, and subsequent loss of control of the helicopter. 

The FAA has reviewed RHC Service Bulletin SB-36, dated November 5, 1999, which describes replacing the sprag clutch, P/N C188-3, S/N 0453 through 0505, inclusive, with sprag clutch, P/N C188-3, S/N 0506 and subsequent. RHC Service Bulletin SB-32, dated March 22, 1999, affected this same P/N, S/N 0003 through 0452. 

Since an unsafe condition has been identified that is likely to exist or develop on other Robinson R44 helicopters of the same type design, this AD is being issued to prevent a sprag clutch failure, loss of main rotor RPM during autorotation, and subsequent loss of control of the helicopter. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability of the helicopter after an actual engine failure. Therefore, replacing sprag clutch, P/N C188-3, S/N 0003 through 0505, inclusive, with sprag clutch, P/N C188-3, S/N 0506 and higher, is required within 30 calendar days or 50 hours time-in-service after the effective date of this AD, whichever occurs first, and this AD must be issued immediately. 

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. 

The FAA estimates that 200 helicopters will be affected by this proposed AD, that it will take approximately 4 work hours to replace a sprag clutch, and that the average labor rate is $60 per work hour. Required parts will cost approximately $3,600 per helicopter. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $768,000. 

## Comments Invited 

                    Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption                     **ADDRESSES**                    . All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.                 

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. 

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 99-SW-70-AD.” The postcard will be date stamped and returned to the commenter. 

The regulations adopted herein will 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, it is determined that this final rule does not have federalism implications under Executive Order 13132. 

                    The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft and that it is not a “significant regulatory action” under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency                           ( print page 20896)                        regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from 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

## Adoption of the Amendment 

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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 a new airworthiness directive (AD), to read as follows: 

**AD 2000-08-04  Robinson Helicopter Company:**                             Amendment 39-11690. Docket No. 99-SW-70-AD.                         

*Applicability:*                             Model R44 Helicopters, serial number (S/N) 0001 through 0541, inclusive, 0543, 0550, 0556, and 0565 with sprag clutch, part number (P/N) C188-3, S/N 0003 through 0505, inclusive, installed, certificated in any category.                         

# Note 1:

This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters 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:*                             Within 30 calendar days or 50 hours time-in-service, whichever occurs first, unless accomplished previously.                         

To prevent sprag clutch failure, loss of main rotor RPM during autorotation, and subsequent loss of control of the helicopter, accomplish the following: 

(a) Replace sprag clutch, P/N C188-3, S/N 0003 through 0505, inclusive, with sprag clutch P/N C188-3, S/N 0506 or higher. 

(b) Remove from the Rotorcraft Flight Manual the Special Pilot Caution, dated March 22, 1999, contained in Robinson Helicopter Company R44 Service Bulletin SB-32 dated March 22, 1999, or the Special Pilot Caution insert in the Normal Procedures Section of the Rotorcraft Flight Manual between pages P.4-8 and P.4-9 required by AD 99-07-18, Docket No. 99-SW-25-AD, Amendment 39-11127 (64 FR 17964, April 13, 1999), as applicable. 

(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, Los Angeles Aircraft Certification Office. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Los Angeles Aircraft Certification Office. 

# Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles Aircraft Certification Office.

(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 helicopter to a location where the requirements of this AD can be accomplished. 

(e) This amendment becomes effective on May 4, 2000.

Issued in Fort Worth, Texas, on April 11, 2000. 

Henry A. Armstrong, 

Manager, Rotorcraft Directorate, Aircraft Certification Service. 

[FR Doc. 00-9818 Filed 4-18-00; 8:45 am] 

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