AD 70-05-05
final rule
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | True Flight Holdings LLC | AA-1 | Airworthiness Directives; American Aviation Model AA-1 Aircraft |
Unsafe Condition
Cracks in the muffler or shroud assembly (P/N 14-504001) adjacent to welds could allow exhaust fumes to enter the cabin heat system.
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Required Actions
Inspect muffler and shroud assembly for cracks near welds, pressure test if visual inspection is not possible, repair cracks with Heliarc welding, check alignment of rigid brace P/N 503008-501 with tailpipe, and follow Advisory Circular 43.13-1 guidelines. Repetitive inspections every 50 hours in service are required unless a new Turbo system P/N 099001-113 is installed.
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Compliance Time
within the next 10 hours in service after the effective date of this Airworthiness Directive, unless already accomplished, and thereafter at intervals not to exceed 50 hours in service from the last inspection
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Affected Aircraft
American Aviation Model AA-1 aircraft, Serial Nos. AA-1-0001 through AA-1-0159.
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Federal Register Abstract
Muffler Inspection
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_70-05-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 70-05-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; American Aviation Model AA-1 Aircraft Subject: Muffler Inspection Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 03/13/1970 Make: True Flight Holdings LLC Model: AA-1 Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 70-05-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-950 AD NUMBER: 70-05-05 SUBJECT HEADING: Airworthiness Directives; American Aviation Model AA-1 Aircraft ACTION: SUMMARY: DATES: Effective March 13, 1970. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 70-05-05 AMERICAN AVIATION: Amdt. 39-950. Applies to Model AA-1 aircraft, Serial Nos. AA-1-0001 through AA-1-0159. Compliance required within the next 10 hours in service after the effective date of this Airworthiness Directive, unless already accomplished, and thereafter at intervals not to exceed 50 hours in service from the last inspection, except as provided in paragraph 3. To preclude the possibility of exhaust fumes from entering the cabin heat system due to undetected cracks in the muffler, accomplish the following: 1. Inspect muffler and shroud assembly (P/N 14-504001) for cracks particularly in the area adjacent to all welds inside the shroud at the transition between the muffler and the tailpipe. If visual inspection is not possible, pressure test for leaks in accordance with AC 43.13- 1, Chap 14, Section 3, paragraph 287D. If cracks are found in the muffler tailpipe or the muffler shroud they should be repaired by an inert gas-shielded arc welding process such as Heliarc. (Muffler material is AISI 321 stainless steel and shroud material is AISI 304 stainless steel). Accomplish above inspection and necessary repairs in accordance with Advisory Circular 43.13- 1, Chap. 14, Section 3, paragraph 387 and 388. 2. Check alignment between rigid brace P/N 503008-501 and tailpipe to insure that tailpipe is not stressed when brace is installed. 3. The repetitive 50 hour inspection requirement of the exhaust system may be omitted if the aircraft has been altered by installation of a new muffler, Turbo system P/N 099001-113, with the rigid brace. (American Aviation Service Bulletin No. 116 dated 9 January 1970 covers this same subject) This amendment is effective March 13, 1970. FOOTER:
Document Text
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AD Final Rules - DRS_70-05-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 70-05-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; American Aviation Model AA-1 Aircraft Subject: Muffler Inspection Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 03/13/1970 Make: True Flight Holdings LLC Model: AA-1 Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 70-05-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-950 AD NUMBER: 70-05-05 SUBJECT HEADING: Airworthiness Directives; American Aviation Model AA-1 Aircraft ACTION: SUMMARY: DATES: Effective March 13, 1970. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 70-05-05 AMERICAN AVIATION: Amdt. 39-950. Applies to Model AA-1 aircraft, Serial Nos. AA-1-0001 through AA-1-0159. Compliance required within the next 10 hours in service after the effective date of this Airworthiness Directive, unless already accomplished, and thereafter at intervals not to exceed 50 hours in service from the last inspection, except as provided in paragraph 3. To preclude the possibility of exhaust fumes from entering the cabin heat system due to undetected cracks in the muffler, accomplish the following: 1. Inspect muffler and shroud assembly (P/N 14-504001) for cracks particularly in the area adjacent to all welds inside the shroud at the transition between the muffler and the tailpipe. If visual inspection is not possible, pressure test for leaks in accordance with AC 43.13- 1, Chap 14, Section 3, paragraph 287D. If cracks are found in the muffler tailpipe or the muffler shroud they should be repaired by an inert gas-shielded arc welding process such as Heliarc. (Muffler material is AISI 321 stainless steel and shroud material is AISI 304 stainless steel). Accomplish above inspection and necessary repairs in accordance with Advisory Circular 43.13- 1, Chap. 14, Section 3, paragraph 387 and 388. 2. Check alignment between rigid brace P/N 503008-501 and tailpipe to insure that tailpipe is not stressed when brace is installed. 3. The repetitive 50 hour inspection requirement of the exhaust system may be omitted if the aircraft has been altered by installation of a new muffler, Turbo system P/N 099001-113, with the rigid brace. (American Aviation Service Bulletin No. 116 dated 9 January 1970 covers this same subject) This amendment is effective March 13, 1970. FOOTER:
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Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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