On February 4, 1998, the FAA issued priority letter AD 98-04-12, applicable to RHC Model R44 helicopters, which requires an initial and repetitive measurement of the shaft diameter, and replacement of the spring assembly if the shaft diameter is excessively worn. That action was prompted by an incident in which a pilot felt binding in the cyclic control when attempting to move it to the left. A precautionary landing was made using only right-hand turns. Subsequent inspection revealed that a notch was worn in the shaft, which caused the shaft and spring to move from the lower mount and interfere with the lateral control. Inspection of a second RHC Model 44 helicopter revealed similar wear. Excessive wear can create a notch on the shaft, which can cause the spring assembly to move out of its lower mount. This condition, if not corrected, could lead to the shaft interfering with lateral cyclic control, which could result in loss of control of the helicopter.
The FAA has reviewed Robinson Helicopter Company R44 Service Bulletin SB-26, dated January 31, 1998, which describes procedures for measurement of the shaft diameter, and replacing the spring assembly with a modified spring assembly if the shaft diameter varies more than 0.004 inch in any 0.50 inch of length.
Since the unsafe condition described is likely to exist or develop on other RHC Model R44 helicopters of the same type design, the FAA issued priority letter AD 98-04-12 to prevent the shaft from interfering with lateral cyclic control, which could result in loss of control of the helicopter. The AD requires, within 10 hours time-in-service (TIS) after the effective date of this AD, and thereafter at intervals not to exceed 20 hours TIS until replacement of the spring assembly with a modified spring assembly is accomplished, a measurement of the shaft diameter; and replacement of the C056-1 Rev. A through G spring assembly with a C056-1 Rev. H spring assembly ifthe shaft diameter measurement varies more than 0.004 inch in any 0.50 inch of length. Replacement of the C056-1 Rev. A through G spring assembly with a C056-1 Rev. H spring assembly is considered terminating action for the requirements of this AD. The actions are required to be accomplished in accordance with the service bulletin described previously.
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on February 4, 1998 to all known U.S. owners and operators of RHC Model R44 helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.
Comments Invited
Although this action is in the form of a final rulethat 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 willbe 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. 98-SW-08-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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
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 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, Incorporation by reference, 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 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: