AD 94-20-03

On November 18, 1993, the FAA issued Priority Letter AD 93-22-11, applicable to Bell Helicopter Textron, Inc. (BHTI) Model 206A, 206B, 206B-1, 206L, 206L-1, 206L-3, and 206L-4 helicopters, to require an inspection of the main rotor hub trunnion (trunnion), part number (P/N) 206-011-113-103 and P/N 206-011-120-103, for proper positioning of the trunnion master spline and replacement of any trunnion that had a mislocated master spline. That action was prompted by a manufacturer's report that certain trunnions were manufactured with a mislocated master spline. The manufacturer's data showed that when the trunnion master spline is mislocated, the main rotor mast does not align properly, so the operator's input to the cyclic stick does not produce the desired result in the main rotor system. After reviewing the manufacturer's data, the FAA determined that any mislocated trunnion master spline creates an unsafe condition. This condition, if not corrected, could result in pitch link misalignment, altered cyclic stick control position, loss of the main rotor system, and subsequent loss of control of the helicopter.

Since the issuance of that AD, BHTI has issued a revised Alert Service Bulletin (ASB) for Model 206L, 206L-1, 206L-3, and 206L-4 helicopters. ASB 206L-93-90, Revision A, dated November 9, 1993, changed Figure 3 to show that the center line of the trunnion should go through the crown rather than the inset of the master spline. ASB 206-93-75, dated October 19, 1993, which is applicable to Model 206A, 206B, and 206B-1 helicopters, has a correct Figure 3 showing that the center line of the trunnion should go through the inset rather than the crown of the master spline.

Since an unsafe condition has been identified that is likely to exist or develop on other BHTI Model 206 helicopters of this same type design, this AD supersedes Priority Letter AD 93-22-11 to require, within the next 50 hours time-in-service (TIS) or90 calendar days after the effective date of this AD, whichever occurs first, an inspection of the trunnion for proper positioning of the trunnion master spline, and replacement of any trunnion that has a mislocated master spline. The actions are required to be accomplished in accordance with the BHTI ASB 206-93-75, dated October 19, 1993, for Model 206A, 206B, and 206B-1 helicopters, and BHTI ASB 206L-93-90, Revision A, dated November 9, 1993, for Model 206L, 206L-1, 206L-3, and 206L-4 helicopters, described previously. Due to the criticalness of correct alignment of the trunnion master spline and a compliance time that is short for some operators of frequently-used helicopters, this rule must be issued immediately to correct an unsafe condition in aircraft.

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 good cause exists for making this amendment effective in less than 30 days.

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 Number 94-SW-07-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 isdetermined 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

39.13 - [AMENDED] 2. Section 39.13 is amended by adding a new airworthiness directive (AD), Amendment 39-9031, to read as follows: