AD 94-15-07

This amendment adopts a new airworthiness directive (AD) that is applicable to Bell Helicopter Textron, Inc. Model 206A, 206B, 206L, 206L-1, 206L-3, and 206L-4 series helicopters. This action requires a one-time inspection for cracks in a portion of the main rotor blade (blade) trailing edge and the inboard trim tab, and replacement of the blade or trim tab as necessary. This amendment is prompted by reports of cracks in the blade trailing edge near the inboard trim tab. The actions specified in this AD are intended to prevent failure of a main rotor blade and subsequent loss of control of the helicopter.

Final rule; request for comments

94-15-07 BELL HELICOPTER TEXTRON, INC. (BHTI) : Amendment 39-8978. Docket Number 94-SW-01-AD.
Applicability: Model 206A and 206B helicopters, equipped with main rotor blade (blade), part number (P/N) 206-010-200-133, having a serial number with prefix "A", and Model 206L, 206L-1, 206L-3, and 206L-4 helicopters, equipped with blade, P/N 206-015-001-107, having a serial number beginning with prefix "A", except for those blades with serial numbers listed as exempt in the "Helicopters Affected" section of BHTI Alert Service Bulletin 206-93-77, for Models 206A and 206B and in Alert Service Bulletin 206L-93-92, for Models 206L, 206L-1, 206L-3, and 206L-4, both dated November 17, 1993, certificated in any category.

Compliance: Required within 50 hours' time-in-service after the effective date of this airworthiness directive (AD), unless accomplished previously.

To prevent failure of a main rotor blade and subsequent loss of control of the helicopter, accomplish the following:

(a) Conduct a one-time inspection for cracks in each blade's inboard trim tab and trailing edge in accordance with steps 1, 2, and 3 of Part I of the Accomplishment Instructions of applicable Alert Service Bulletin (ASB) 206-93-77 or ASB 206L-93-92, both dated November 17, 1993.

(1) If the blade skin is cracked, remove the blade and replace it with an airworthy blade before further flight.

(2) If only the trim tab is cracked, remove the affected blade from the helicopter. Remove the trim tab and adhesive from the blade and inspect the upper and lower blade skins with a 10-power or higher magnifying glass in accordance with Part II of the Accomplishment Instructions of the applicable ASB, dated November 17, 1993.

(i) If the blade skin under the trim tab is cracked, remove the blade and replace it with an airworthy blade before further flight.(ii) If no crack is detected in the blade skin, polish out all marks on the blade in accordance with Part II, step 4 of the Accomplishment Instructions of the applicable ASB, dated November 17, 1993, and inspect and install a new trim tab in accordance with Part II, steps 5-9 of the Accomplishment Instructions of the applicable ASB, dated November 17, 1993.

(3) If no crack is found in the inboard trim tab or the blade trailing edge by the inspections required by paragraphs (1) and (2), before further flight, inspect the plan-form radii of the trim tab where the trim tab intersects the trailing edge in accordance with Part I, steps 4-6, of the Accomplishment Instructions of the applicable ASB, dated November 17, 1993.

(i) If a crack is found in the plan-form radii of the inboard trim tab, before further flight, remove the blade and replace it with an airworthy blade.(ii) If no crack is found in the plan-form radii of the trim tab, polish and refinish the blade in accordance with Part I, steps 8-11, of the Accomplishment Instructions of the applicable ASB, dated November 17, 1993.

(b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used when approved by the Manager, Rotorcraft Certification Office, FAA, Rotorcraft Directorate. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office.

NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Rotorcraft Certification Office.

(c) 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.

(d) The inspection, rework, and replacement, if necessary, shall be done in accordance with BHTI Alert Service Bulletin 206-93-77 or Alert Service Bulletin 206L-93-92 as applicable, both dated November 17, 1993. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Bell Helicopter Textron, Inc., P.O. Box 482, Fort Worth, Texas 76101. Copies may be inspected at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(e) This amendment becomes effective on August 26, 1994.

This amendment adopts a new airworthiness directive (AD) that is applicable to Bell Helicopter Textron, Inc. (BHTI) Model 206A, 206B, 206L, 206L-1, 206L-3, and 206L-4 series helicopters. Reports indicate that cracks have occurred in the blade trailing edge at the inboard trim tab radius affecting the upper and lower trim tabs. In one instance, the crack propagated through the trailing edge strip, through both the upper and lower blade skins, and forward to the blade spar. Field and laboratory investigations revealed that the cracks started at sanding or grinding marks in the trim tab radius areas. The FAA has reviewed the reports and determined that cracks in the blade trailing edge or the inboard trim tab could create an unsafe condition. This condition, if not corrected, could result in failure of a main rotor blade and subsequent loss of control of the helicopter.

The FAA has reviewed and approved BHTI Alert Service Bulletin 206-93-77 and Alert Service Bulletin 206L-93-92, both dated November 17, 1993, which describe procedures for a one-time inspection for cracks in a portion of the blade trailing edge and the inboard trim tab within 50 hours' time-in-service (TIS), and replacing the blade or inboard trim tab as necessary; or reworking the blade trailing edge and trim tab.

Since an unsafe condition has been identified that is likely to exist or develop on other BHTI Model 206A, 206B, 206L, 206L-1, 206L-3, and 206L-4 series helicopters of the same type design, this AD is being issued to prevent failure of a main rotor blade and subsequent loss of control of the helicopter. This AD requires, within 50 hours' TIS, a one-time inspection for cracks in each blade's trailing edge and inboard trim tab, and replacement of the blade or inboard trim tab as necessary or rework of the blade trailing edge and trim tab. The actions are required to be accomplished in accordance with the service bulletins 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 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-01-AD." The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will not have substantial direct effectson 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: