AD 85-07-01

85-07-01 BELL HELICOPTER TEXTRON, INC.: Amendment 39-5016. Applies to Bell Helicopter Textron, Inc., Model 412 helicopters, S/N's 33001 through 33110, equipped with main rotor pitch horn assembly, P/N 412-010-149-105, and main rotor pins, P/N 412-010-180- 101.

Compliance is required as indicated, unless already accomplished.

To detect possible cracks in the main rotor pitch horn, accomplish the following on Model 412 helicopters equipped with pitch horns, P/N 412-010-149-105:

(a) Within the next 20 hours time in service after the effective date of this AD and thereafter at intervals not to exceed 20 hours time in service from the last inspection, visually inspect the main rotor pitch horn assembly for cracks in accordance with Part I of Bell Helicopter Textron, Inc., Alert Service Bulletin (ASB) 412-83-13, Rev. A, dated August 31, 1983.

(b) Whenever the main rotor pitch horn assembly is removed for any reason, magnetic particle inspect it for cracks in accordance with Part II of ASB 412-83-13, Rev. A, dated August 31, 1983.

(c) If a crack is found during these inspections replace the pitch horn and pins with serviceable parts.

(d) Prior to installation of the pitch horn and pins, visually inspect the spindle joint for surface defects and corrosion. Note: Component repair and overhaul manual BHT-412-CR & 0-1, Rev. 4, April 15, 1984, Figure 65-10-5 contains allowable damage limits.

NOTE: Further inspections are not required when the following parts are installed: 412-010-149-111 Pitch Horn Assembly -4 required per helicopter. 412-010-180-103 Pin -32 required per helicopter. (Bell Helicopter Textron, Inc., Alert Service Bulletin 412-84-l8, November 19, 1984, pertains to replacement of new horns and pins.)

The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directivewho have not already received these documents from the manufacturer may obtain copies upon request to Bell Helicopter Textron, Inc., P.O. Box 482, Fort Worth, Texas 76101. These documents may also be examined in the Rules Docket located at the Office of the Regional Counsel, Southwest Region, Federal Aviation Administration, Room 158, Building 3B, 4400 Blue Mound Road, Fort Worth, Texas 76106.

Any alternate methods or equivalent procedures must be approved by Mr. James D. Erickson, Manager, Helicopter Certification Branch, ASW-170, Building 3, Room 211, 4400 Blue Mound Road, Fort Worth, Texas 76106.

This amendment becomes effective April 10, 1985.