AD 49-28-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Sierra Hotel Aero, Inc. | Navion (Army L-17A) | Airworthiness Directives; All Navion Airplanes Equipped With Product Techniques, Inc., Propeller Spinners |
| aircraft | Sierra Hotel Aero, Inc. | Navion A (Army L-17B and L-17C) | Airworthiness Directives; All Navion Airplanes Equipped With Product Techniques, Inc., Propeller Spinners |
Unsafe Condition
Unsatisfactory spinner bulkheads with thickness less than 0.045 inch at the perimeter may fail, leading to propeller spinner detachment.
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Required Actions
Inspect spinner bulkhead thickness at perimeter, 1/2 inch from edge. Replace bulkheads measuring less than 0.045 inch. Spinners with 0.058-inch or 0.064-inch cadmium plated steel bulkheads do not require inspections. Those with thinner steel or aluminum must be inspected and replaced if under 0.045 inch.
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Compliance Time
Before further flight, or within the next 50 hours of flight for spinners that passed previous inspections.
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Affected Aircraft
Sierra Hotel Aero, Inc. Navion (Army L-17A) and Navion A (Army L-17B and L-17C) airplanes equipped with Product Techniques, Inc. propeller spinners.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Unsatisfactory Spinner
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_49-28-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 49-28-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; All Navion Airplanes Equipped With Product Techniques, Inc., Propeller Spinners Subject: Unsatisfactory Spinner Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Sierra Hotel Aero, Inc. Model: Navion (Army L-17A) | Navion A (Army L-17B and L-17C) Product Type: Aircraft Product Subtype: Small Airplane Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 49-28-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 49-28-01 SUBJECT HEADING: Airworthiness Directives; All Navion Airplanes Equipped With Product Techniques, Inc., Propeller Spinners ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 49-28-01 NAVION: Applies to All Airplanes Equipped With Product Techniques, Inc., Propeller Spinners. To be accomplished as specified below: In order to preclude the possibility of continued use of any unsatisfactory spinners which may be in existence, the following steps must be taken: 1. Spinners not previously installed on an aircraft must be inspected before installation for the thickness of the bulkhead. This may be accomplished by measuring the thickness of the bulkhead at the perimeter; measurements should be taken about 1/2 inch from the edge for best accuracy. The manufacturing process used in fabricating the bulkheads reduces the gage of the material about 0.012 inch at the perimeter. Bulkheads measuring less than 0.045 inch at this point must be replaced with heavier gage steel bulkheads. 2. Spinners which have partially completed the inspections previously required by AD 49-01-01 may continue in service until the next 10-hour inspection at which time the bulkhead should be gaged as specified above and replace if under 0.045-inch thickness. 3. Spinners having satisfactorily passed the five inspection periods required by AD 49-01-01 must be inspected for bulkhead thickness, as specified above, within the next 50 hours of flight, and replaced if under 0.045-inch thickness. It has been determined that bulkheads of 0.058-inch and 0.064-inch cadmium plated steel are satisfactory and do not require the periodic inspections previously specified in AD 49-01-01. However, bulkheads made of thinner gage steel, or of aluminum, are unsatisfactory. This supersedes AD 49-01-01. FOOTER:
Document Text
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AD Final Rules - DRS_49-28-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 49-28-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; All Navion Airplanes Equipped With Product Techniques, Inc., Propeller Spinners Subject: Unsatisfactory Spinner Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Sierra Hotel Aero, Inc. Model: Navion (Army L-17A) | Navion A (Army L-17B and L-17C) 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: 49-28-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 49-28-01 SUBJECT HEADING: Airworthiness Directives; All Navion Airplanes Equipped With Product Techniques, Inc., Propeller Spinners ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 49-28-01 NAVION: Applies to All Airplanes Equipped With Product Techniques, Inc., Propeller Spinners. To be accomplished as specified below: In order to preclude the possibility of continued use of any unsatisfactory spinners which may be in existence, the following steps must be taken: 1. Spinners not previously installed on an aircraft must be inspected before installation for the thickness of the bulkhead. This may be accomplished by measuring the thickness of the bulkhead at the perimeter; measurements should be taken about 1/2 inch from the edge for best accuracy. The manufacturing process used in fabricating the bulkheads reduces the gage of the material about 0.012 inch at the perimeter. Bulkheads measuring less than 0.045 inch at this point must be replaced with heavier gage steel bulkheads. 2. Spinners which have partially completed the inspections previously required by AD 49-01-01 may continue in service until the next 10-hour inspection at which time the bulkhead should be gaged as specified above and replace if under 0.045-inch thickness. 3. Spinners having satisfactorily passed the five inspection periods required by AD 49-01-01 must be inspected for bulkhead thickness, as specified above, within the next 50 hours of flight, and replaced if under 0.045-inch thickness. It has been determined that bulkheads of 0.058-inch and 0.064-inch cadmium plated steel are satisfactory and do not require the periodic inspections previously specified in AD 49-01-01. However, bulkheads made of thinner gage steel, or of aluminum, are unsatisfactory. This supersedes AD 49-01-01. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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