This amendment adopts a new airworthiness directive (AD) that is applicable to McDonnell Douglas Helicopter Systems (MDHS) and Hughes Helicopters, Inc. (Hughes) Model 369D, E, F, and FF series helicopters. MDHS received a report that indicated a pitch control assembly lockwasher (lockwasher), part number (P/N) MS172209, had failed in service. A subsequent investigation revealed that some lockwashers appear to have dents at the inner tang inside radius. The FAA has reviewed the reports and determined that failure of this tang could allow the locknut to loosen and eventually allow the pitch control assembly to disengage from the tail rotor assembly. Should these two tail rotor components separate, the rotorcraft crew would lose the capability of making necessary anti-torque corrections through the tail rotor to maintain adequate control of the helicopter. This condition, if not corrected, could result in failure of the inner tang of the lockwasher, loss of the locknut, disengagement of the pitch control assembly, loss of tail rotor control, and subsequent loss of control of the helicopter.
The FAA has reviewed McDonnell Douglas Helicopter Systems Service Information Notice (SIN) No. DN-185, EN-78, and FN-64, dated September 23, 1994, which describes procedures for an inspection of the lockwasher, P/N MS172209, application of a torque stripe on the tail rotor swashplate and locknut, and repetitive inspections of the pitch control assembly to detect slippage of the locknut.
Since an unsafe condition has been identified that is likely to exist or develop on other McDonnell Douglas Helicopter Systems and Hughes Helicopters, Inc. Model 369D, E, F, and FF series helicopters of the same type design, this AD is being issued to prevent failure of the inner tang of the lockwasher, loss of the locknut, disengagement of the pitch control assembly, loss of tail rotor control, and subsequent loss of control of the helicopter. This AD requires an initial inspection of the lockwasher for dents in the inner tang inside radius, application of a torque stripe on the tail rotor swashplate and locknut, and repetitive inspections of the torque stripe to detect slippage of the locknut. Due to the critical need to ensure the integrity of the lockwasher and the short time-in-service before the initial inspection is required, this rule must be issued immediately to correct an unsafe condition in the affected helicopters. The actions are required to be accomplished in accordance with the SIN described previously.
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.
Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded bynotice 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. 94-SW-13-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. 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 to read as follows: