AD 47-21-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sierra Hotel Aero, Inc. | Navion (Army L-17A) | Airworthiness Directives; Navion Serial Numbers NAV-4-11 Through 21 and 44 Through 47 |
Unsafe Condition
The original propeller control lacks a positive friction lock, which could result in unintended movement of the propeller control lever during flight.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace the original propeller control with one incorporating a positive friction lock as per NAA Kit Drawing 145-89011. Refer to NAA Field Service Bulletin No. 5 for guidance.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
not later than August 1, 1947
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Affected Aircraft
Sierra Hotel Aero, Inc. Navion (Army L-17A) serial numbers NAV-4-11 through 21 and 44 through 47
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Propeller Control Friction Lock
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_47-21-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 47-21-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Navion Serial Numbers NAV-4-11 Through 21 and 44 Through 47 Subject: Propeller Control Friction Lock Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Sierra Hotel Aero, Inc. Model: Navion (Army L-17A) Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 47-21-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 47-21-05 SUBJECT HEADING: Airworthiness Directives; Navion Serial Numbers NAV-4-11 Through 21 and 44 Through 47 ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 47-21-05 NAVION: (Was Mandatory Note 4 of AD-782-3.) Applies to Serial Numbers NAV-4-11 Through 21 and 44 Through 47. To be accomplished not later than August 1, 1947. Replace the original propeller control with one that incorporates a positive friction lock in accordance with NAA Kit Drawing 145-89011. (NAA Field Service Bulletin No. 5 covers this change.) FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_47-21-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 47-21-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; Navion Serial Numbers NAV-4-11 Through 21 and 44 Through 47 Subject: Propeller Control Friction Lock Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Sierra Hotel Aero, Inc. Model: Navion (Army L-17A) 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: 47-21-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 47-21-05 SUBJECT HEADING: Airworthiness Directives; Navion Serial Numbers NAV-4-11 Through 21 and 44 Through 47 ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 47-21-05 NAVION: (Was Mandatory Note 4 of AD-782-3.) Applies to Serial Numbers NAV-4-11 Through 21 and 44 Through 47. To be accomplished not later than August 1, 1947. Replace the original propeller control with one that incorporates a positive friction lock in accordance with NAA Kit Drawing 145-89011. (NAA Field Service Bulletin No. 5 covers this change.) 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
2008-05-14 Recurring
final ruleAirworthiness Directives; Sierra Hotel Aero, Inc. Models Navion (L-17A), Navion A (L-17B), (L-17C), Navion B, Navion D, Navion E, Navion F, Navion G, and Navion H Airplanes
Unsafe Condition: Leaking or improperly operating fuel selector valves may disrupt fuel flow to the engine, leading to engine power loss.
68-20-06
final ruleAirworthiness Directives; Navion Models Navion through Navion H Airplanes
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62-03-03
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Unsafe Condition: The landing gear selector valve end fitting P/N 145-58145-3 (heat treated and non-heat treated) has a service history of failure during attempts to extend the gear.
47-31-03
final ruleAirworthiness Directives; Navion Serial Numbers NAV-4-2 Through NAV-4-1010 Which Incorporate Koehler Model 2250 Fuel Strainers
Unsafe Condition: Loss of fuel pressure due to air leakage into the fuel system through the CCA-1550-1/8 drain cock on the Koehler Model 2250 fuel strainer.
