AD 71-21-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Piper Aircraft Inc. | PA-23-250 (Navy UO-1) | Airworthiness Directives; Piper Model PA 23-250 Airplanes |
Unsafe Condition
Failure of the existing alternate air flexible duct (P/N 22502-65) could allow fire to pass through the engine firewall in the event of a powerplant fire.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace the existing alternate air flexible duct P/N 22502-65 with new fireproof duct P/N 48076-02, following Piper Service Bulletin 334 or an equivalent approved duct. Compliance may be requested to be extended by the FAA.
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Compliance Time
within the next 50 hours' time in service after the effective date of this airworthiness directive unless already accomplished
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Affected Aircraft
Piper Aircraft Inc. Model PA-23-250 (Navy UO-1) serial numbers 27-4053, 27-4226 through 27-4563 inclusive, 27-4565 through 27-4579 inclusive, 27-4581 through 27-4617 inclusive, 27-4619 through 27-4627 inclusive, 27-4630 through 27-4636 inclusive.
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Federal Register Abstract
Engine Firewall Flex Duct
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_71-21-06.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 71-21-06 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Piper Model PA 23-250 Airplanes Subject: Engine Firewall Flex Duct Status: Current Citation: This information is not available. Citation Publish Date: 10/19/1971 Effective Date: 10/12/1971 Make: Piper Aircraft Inc. Model: PA-23-250 (Navy UO-1) Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: AIR-700: Compliance & Airworthiness Division Office of Primary Responsibility: AIR-720: Operational Safety Branch CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 71-21-06 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1309 AD NUMBER: 71-21-06 SUBJECT HEADING: Airworthiness Directives; Piper Model PA 23-250 Airplanes ACTION: SUMMARY: DATES: Effective October 12, 1971. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 71-21-06 PIPER: Amendment 39-1309. Applies to Turbocharged Type PA 23-250 airplanes Serial Numbers 27-4053, 27-4226 through 27-4563 inclusive, 27-4565 through 27-4579 inclusive, 27-4581 through 27-4617 inclusive, 27-4619 through 27-4627 inclusive, 27-4630 through 27-4636 inclusive. Compliance required within the next 50 hours' time in service after the effective date of this airworthiness directive unless already accomplished. To preclude the possibility of fire passing through the engine firewall, in the event of a powerplant fire, replace the existing alternate air flexible duct, P/N 22502-65, with new alternate air duct P/N 48076-02 (fireproof), in accordance with Piper Service Bulletin Number 334 dated 17 March 1971, or later approved revision, or replace with an equivalent alternate air duct approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Upon request with substantiating data submitted through an FAA maintenance inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. This amendment is effective October 12, 1971. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_71-21-06.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 71-21-06 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Piper Model PA 23-250 Airplanes Subject: Engine Firewall Flex Duct Status: Current Citation: This information is not available. Citation Publish Date: 10/19/1971 Effective Date: 10/12/1971 Make: Piper Aircraft Inc. Model: PA-23-250 (Navy UO-1) Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: AIR-700: Compliance & Airworthiness Division Office of Primary Responsibility: AIR-720: Operational Safety Branch CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 71-21-06 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1309 AD NUMBER: 71-21-06 SUBJECT HEADING: Airworthiness Directives; Piper Model PA 23-250 Airplanes ACTION: SUMMARY: DATES: Effective October 12, 1971. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 71-21-06 PIPER: Amendment 39-1309. Applies to Turbocharged Type PA 23-250 airplanes Serial Numbers 27-4053, 27-4226 through 27-4563 inclusive, 27-4565 through 27-4579 inclusive, 27-4581 through 27-4617 inclusive, 27-4619 through 27-4627 inclusive, 27-4630 through 27-4636 inclusive. Compliance required within the next 50 hours' time in service after the effective date of this airworthiness directive unless already accomplished. To preclude the possibility of fire passing through the engine firewall, in the event of a powerplant fire, replace the existing alternate air flexible duct, P/N 22502-65, with new alternate air duct P/N 48076-02 (fireproof), in accordance with Piper Service Bulletin Number 334 dated 17 March 1971, or later approved revision, or replace with an equivalent alternate air duct approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Upon request with substantiating data submitted through an FAA maintenance inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. This amendment is effective October 12, 1971. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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