Transport Canada, which is the airworthiness authority for Canada, recently notified the FAA that an unsafe condition may exist on BHTC Model 230 helicopters. Transport Canada advises that fatigue cracks at the bolt holes of the pitch horn and in the flapping bearing assembly can lead to loss of control of the helicopter.
BHTC issued Alert Service Bulletin No. 230-98-13, dated April 23, 1998 (ASB), which specifies inspecting the main rotor hub in the areas between the pitch horn and main rotor grip tangs (grip tangs) and between the flapping bearing assembly and the main rotor yoke assembly for fretting. The ASB also specifies torque verification procedures for the main rotor grip retaining bolts and the flapping bearing assembly retaining bolts. Transport Canada classified this ASB as mandatory and issued Transport Canada AD CF-98-17, dated July 15, 1998, to ensure the continued airworthiness of these helicopters in Canada.
This helicopter model is manufactured in Canada 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, Transport Canada has kept the FAA informed of the situation described above. The FAA has examined the findings of Transport Canada, 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.
The FAA estimates that 17 helicopters will be affected by this AD, that it will take approximately 1 work hour to accomplish the inspection and retorque of bolts, if necessary, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $3,060 per year, assuming three inspections and retorques per year and assuming that no parts will need to be replaced.
Since an unsafe condition has been identified that is likely to exist or develop on other BHTC Model 230 helicopters of the same type design registered in the United States, this AD is being issued to prevent fretting induced fatigue cracking of the flapping bearing assembly and around the bolt holes of the pitch horn, loss of the rotor system, and subsequent loss of control of the helicopter. This AD requires recurring inspections of the main rotor hub in the areas between the pitch horn and grip tangs and between the flapping bearing assembly and the main rotor yoke assembly for fretting. If fretting is found on any part, replacing that part with an airworthy part is required. This AD also requires verifying the torque on the main rotor grip retaining bolts and the flapping bearing assembly retaining bolts. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability of the helicopter. Therefore, a visual inspection of the main rotor hub between the pitch horn and grip tangs and the flapping bearing assembly and the main rotor yoke assembly for fretting is required. A torque check of the main rotor grip retaining bolts and the flapping bearing assembly retaining bolts is also required. These actions are required within 10 hours TIS 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.
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. 98-SW-48-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, 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: