AD 73-21-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Bell Helicopter Textron Canada Limited | 206A | Airworthiness Directives; Bell Model 206A and 206B Helicopters |
| aircraft | Bell Helicopter Textron Canada Limited | 206B | Airworthiness Directives; Bell Model 206A and 206B Helicopters |
Unsafe Condition
Fatigue cracks in the vertical fin support forgings in the area of the fin attachment nut plates could result in structural failure of the vertical fin support system.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove the vertical fin, remove paint in the area of the fin attachment nut plates, inspect for cracks using dye penetrant or equivalent method, replace cracked forgings prior to further flight, remove thread marks in holes per Service Bulletin 206-01-73-5, and reinstall the fin. If support forgings were replaced per Service Bulletin 206-01-73-5 Part II, this AD is not applicable.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
within the next 50 hours' time in service after the effective date of this A.D.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Bell Helicopter Textron Canada Limited Model 206A and 206B helicopters, serial numbers 4 through 1097, equipped with vertical fin support forgings P/N 206-031-417 and -418.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Vertical Fin Support Forgings
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_73-21-03.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 73-21-03 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Bell Model 206A and 206B Helicopters Subject: Vertical Fin Support Forgings Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 11/15/1973 Make: Bell Helicopter Textron Canada Limited Model: 206A | 206B Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 73-21-03 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1732 AD NUMBER: 73-21-03 SUBJECT HEADING: Airworthiness Directives; Bell Model 206A and 206B Helicopters ACTION: SUMMARY: DATES: Effective November 15, 1973. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_73-21-03.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 73-21-03 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Bell Model 206A and 206B Helicopters Subject: Vertical Fin Support Forgings Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 11/15/1973 Make: Bell Helicopter Textron Canada Limited Model: 206A | 206B Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 73-21-03 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1732 AD NUMBER: 73-21-03 SUBJECT HEADING: Airworthiness Directives; Bell Model 206A and 206B Helicopters ACTION: SUMMARY: DATES: Effective November 15, 1973. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.
Related Airworthiness Directives
2019-08-10
final ruleAirworthiness Directives; Bell Helicopter Textron Canada Limited Helicopters
Unsafe Condition: A blocked oil line restrictor in the freewheel lubrication system could cause failure of the freewheel assembly, failure of the main rotor mast, and subsequent loss of control of the helicopter.
2018-25-17
final ruleAirworthiness Directives; Air Comm Corporation Air Conditioning Systems
Unsafe Condition: An overheated connector, which could result in a fire and subsequent loss of control of the helicopter.
2017-05-04
final ruleAirworthiness Directives; Bell Helicopter Textron Canada Limited Helicopters
Unsafe Condition: Corrosion of a tension-torsion strap (TT strap), which could result in failure of the TT strap and subsequent loss of control of the helicopter.
2013-22-21
final ruleAirworthiness Directives; Bell Helicopter Textron, Inc., Helicopters
Unsafe Condition: Incorrectly installed float inflation hoses, which could result in failure of the emergency floats to inflate fully during an emergency.