AD 97-15-16

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 97-15-16, which was sent previously to all known U.S. owners and operators of BHTC Model 430 helicopters by individual letters. This AD requires inspections of all 4 main rotor adapter assemblies for evidence of flapping contact between the adapter liners and the upper stop assembly plugs, and for evidence of lead-lag contact between the adapter pads and the yoke assembly; installing a never-exceed-velocity (VNE) placard; marking the airspeed indicator to reflect the airspeed restriction; installing a slippage mark on the airspeed indicator glass and instrument case; and inserting revisions to the rotorcraft flight manual to reflect the airspeed revision. This amendment is prompted by a report of a main rotor tip path plane separation, which occurred during a ferry flight at an airspeed of more than 140 knots indicated airspeed (KIAS). The actions specified by this AD are intended to prevent tip path plane separation, increased vibrations, possible damage to the main rotor system, and subsequent loss of control of the helicopter.

Final rule; request for comments

97-15-16 BELL HELICOPTER TEXTRON CANADA: Amendment 39-10152. Docket No. 97-SW-24-AD.

Applicability: Model 430 helicopters, certificated in any category.

NOTE 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must use the authority provided in paragraph (g) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any helicopter from the applicability of this AD.

Compliance: Required before further flight, unless accomplished previously.

To prevent tip path plane separation, increased vibrations, possible damage to the main rotor system, and subsequent loss of control of the helicopter, accomplish the following:

(a) Inspect all 4 main rotor adapter assemblies for evidence of flapping contact between the adapter liners and the upper stop assembly plugs. Refer to Figures 1, 2, and 3 of the Accomplishment Instructions of Bell Helicopter Textron Canada (BHTC) Alert Service Bulletin (ASB) No. 430-97-2, dated July 11, 1997. Flapping contact is indicated by scrubbing (or smudging) of the adapter liner surface, characteristic of relative motion between the surfaces of the adapter lines and upper stop assembly plugs.

(b) Inspect all 4 main rotor adapter assemblies for evidence of lead-lag contact between the adapter pads and the yoke assembly. Refer to Figures 1 and 2 of the Accomplishment Instructions of BHTC ASB No. 430-97-2, dated July 11, 1997. Lead-lag contact is indicated by a permanent indentation or split in the surface of the adapter pads.

(c) If the inspections in paragraphs (a) or (b) of this AD reveal that there has been contact, inspect and replace the main rotor yoke and stop assemblies in accordance with Part I, No. 3 of the Accomplishment Instructions of BHTC ASB No. 430-97-2, dated July 11, 1997.

(d) For helicopters equipped with skid landing gear or retractable landing gear, remove the existing never-exceed-velocity (VNE) placard from the overhead console and install VNE placard, P/N 430-075-208-107, or P/N 430-075-208-109, as applicable, in accordance with Part II, of the Accomplishment Instructions of BHTC ASB No. 430-97-2, dated July 11, 1997.

(e) Install on each airspeed indicator a red arc between 120 knots and 150 knots to indicate that airspeeds above 120 knots indicated airspeed are prohibited. Install a slippage mark on each airspeed indicator glass and instrument case.

(f) Insert the temporary revisions, BHT-430-FM-1 and BHT-430-FMS-1, as appropriate, both dated July 7, 1997, into the rotorcraft flight manual.

(g) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Rotorcraft Certification Office, Rotorcraft Directorate, FAA. 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Rotorcraft Certification Office.

(h) Special flight permits will not be issued.

(i) The inspections and installations shall be done in accordance with Bell Helicopter Textron Alert Service Bulletin (ASB) No. 430-97-2, dated July 11, 1997. 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 Canada, 12,800 Rue de l'Avenir, Mirabel, Quebec JON 1LO, telephone (800) 463-3036, fax (514) 433-0272. 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.

(j) This amendment becomes effective on October 24, 1997, to all persons except those persons to whom it was made immediately effective by priority letter AD 97-15-16, issued July 18, 1997, which contained the requirements of this amendment.

On July 18, 1997, the FAA issued priority letter AD 97-15-16, applicable to BHTC Model 430 helicopters, which requires inspections of all 4 main rotor adapter assemblies for evidence of flapping contact between the adapter liners and the upper stop assembly plugs, and for evidence of lead-lag contact between the adapter pads and the yoke assembly; installing a VNE placard; marking the airspeed indicator to reflect the airspeed restriction; installing a slippage mark on the airspeed indicator glass and instrument case; and inserting revisions to the rotorcraft flight manual to reflect the airspeed revision. That action was prompted by one report of a main rotor tip path plane separation, which occurred during a ferry flight at an airspeed of more than 140 KIAS. The separation was observed from the cockpit and caused a vibration at a frequency near one per revolution. BHTC was able to reproduce a similar event on other Model 430 helicopters, and determined that the separation may occur at airspeeds above 120 KIAS. Therefore, flight at airspeeds above 120 KIAS is considered unsafe. This condition, if not corrected, could result in tip path plane separation, increased vibrations, possible damage to the main rotor system, and subsequent loss of control of the helicopter.

The FAA has reviewed Bell Helicopter Textron Alert Service Bulletin (ASB) No. 430-97-2, dated July 11, 1997, which describes inspections of all 4 main rotor adapter assemblies for evidence of flapping contact between the adapter liners and the upper stop assembly plugs; and, for evidence of lead-lag contact between the adapter pads and the yoke assembly. The ASB also describes further inspections if evidence of contact is found during either of those inspections. For helicopters equipped with skid landing gear, removing the existing VNE placard and installing a VNE placard, part number (P/N) 430-075-208-107, is required; and for helicopters equipped with retractable landing gear, removing the existing VNE placard and installing a VNE placard, P/N 430-075-208-109, is required. Finally, the ASB describes marking the airspeed indicators to reflect the airspeed restriction by adding to the instrument glass a red arc to indicate that airspeeds above 120 KIAS are prohibited; and inserting revisions to the rotorcraft flight manual that reflect this airspeed restriction.

Since the unsafe condition described is likely to exist or develop on other BHTC Model 430 helicopters of the same type design, the FAA issued priority letter AD 97-15-16 to prevent tip path plane separation, increased vibrations, possible damage to the main rotor system, and subsequent loss of control of the helicopter. The AD requires, before further flight, inspections of all 4 main rotor adapter assemblies for evidence of flapping contact between the adapter liners and the upper stop assembly plugs, and for evidence of lead-lag contact between the adapter pads and the yoke assembly. Flapping contact is indicated by scrubbing (or smudging) of the adapter liner surface, characteristic of relative motion between the surfaces of the adapter liners and upper stop assembly plugs. Lead-lag contact is indicated by a permanent indentation or split in the surface of the adapter pads. Further inspections are required if evidence of contact is found during either of those inspections. For helicopters equipped with skid landing gear, this AD requires the removing the existing VNE placard and installing a VNE placard, P/N 430-075-208-107; and for helicopters equipped with retractable landing gear, removing the existing VNE placard and installing a VNE placard, P/N 430-075-208-109, is required. Finally, this AD requires marking each airspeed indicator to reflect the airspeed restriction by adding to the instrument glass a red arc to indicate that airspeeds above 120 KIAS are prohibited; installing a slippage mark on each airspeed indicator glass and instrument case; and inserting revisions to the rotorcraft flight manual that reflect the airspeed restriction. 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 July 18, 1997 to all known U.S. owners and operators of BHTC Model 430 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 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 thatsummarizes 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. 97-SW-24-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 DIRECTIVES1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: