AD 73-21-03

73-21-03 BELL: Amdt. 39-1732. Applies to Model 206A and 206B helicopters, serial numbers 4 through 1097, certificated in all categories, equipped with vertical fin support forgings, P/N's 206-031-417 and -418.

Compliance required within the next 50 hours' time in service after the effective date of this A.D., unless already accomplished.

To detect possible fatigue cracks in the vertical fin support forgings in the area of the fin attachment nut plates, accomplish the following:

(a) Remove the vertical fin in accordance with paragraph 8-47, Section VIII of the 206A/B Maintenance and Overhaul Instructions.

(b) Remove the paint in the area of the fin attachment nut plates (4 places).

(c) Inspect for cracks, using a dye penetrant or equivalent inspection method.

(d) If cracks are found in either support forging, the cracked forging must be removed and replaced prior to further flight.

(e) If no cracks are found, inspect the four holes for thread marks. Any marks must be removed in accordance with Bell Helicopter Company Service Bulletin No. 206-01-73-5, Part I, paragraph 5, dated June 27, 1973, or later FAA approved revision. Apply a coating of zinc chromate primer or other suitable corrosion protection.

(f) Reinstall the fin in accordance with paragraph 8-49, Section VIII of the 206A/B Maintenance and Overhaul Instructions.

(g) This A.D. is not applicable if the vertical fin support forgings have been replaced in accordance with Bell Helicopter Company Service Bulletin No. 206-01-73-5, Part II dated June 27, 1973, or later FAA approved revision.

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 directive who have not already received these documents from the manufacturer may obtain copies upon request to the Service Manager, Bell Helicopter Company, P.O. Box 482,Fort Worth, Texas 76101. These documents may also be examined at the Office of the Regional Counsel, Southwest Region, FAA, 4400 Blue Mound Road, Fort Worth, Texas, and at FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C. A historical file on this A.D. which includes the incorporated material in full is maintained by the FAA at its headquarters in Washington, D.C., and at the Southwest Regional Office in Fort Worth, Texas.

This amendment becomes effective November 15, 1973.