AD 78-17-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Canada Corp. | PT6T-3 | PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED Model PT6T-3 and PT6T-6 Engines |
| engine | Pratt & Whitney Canada Corp. | PT6T-3A | PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED Model PT6T-3 and PT6T-6 Engines |
| engine | Pratt & Whitney Canada Corp. | PT6T-6 | PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED Model PT6T-3 and PT6T-6 Engines |
Unsafe Condition
Rupture of the bypass valve diaphragm in the automatic fuel control unit.
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Required Actions
Replace part number 2526477 diaphragm with part number 323451 diaphragm in accordance with Pratt & Whitney Aircraft of Canada, Limited Alert Service Bulletin No. 5153, or approved equivalent parts and procedure. Equivalent parts and procedures must be approved by the Chief, Engineering and Manufacturing Branch, Eastern Region FAA.
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Compliance Time
within the next 50 hours in service after the effective date of this AD
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Affected Aircraft
Pratt & Whitney Aircraft of Canada, Limited PT6T-3 and PT6T-6 turboshaft engines with automatic fuel control using Aviation Electric Ltd. Parts List 2524381-5, 3244712-1 and -2, 3244717-1 through -5, 3244721-1 through -5, 3244735-1 through -7, and 3244737-1 through -7.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Automatic Fuel Control Unit
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_78-17-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 78-17-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED Model PT6T-3 and PT6T-6 Engines Subject: Automatic Fuel Control Unit Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 08/31/1978 Make: Pratt & Whitney Canada Corp. Model: PT6T-3 | PT6T-3A | PT6T-6 Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 78-17-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3285 AD NUMBER: 78-17-05 SUBJECT HEADING: PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED Model PT6T-3 and PT6T-6 Engines ACTION: SUMMARY: DATES: Effective August 31, 1978. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 78-17-05 PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED: Amendment 39-3285. Applies to all Pratt & Whitney Aircraft of Canada, Limited PT6T-3 and PT6T-6 turboshaft engines with automatic fuel control with Aviation Electric Ltd. Parts List 2524381-5, 3244712-1 and -2, 3244717-1 through -5, 3244721-1 through -5, 3244735-1 through -7 and 3244737-1 through -7. Compliance required within the next 50 hours in service, after the effective date of this AD, unless already accomplished. To preclude rupture of the bypass valve diaphragm in the automatic fuel control unit, replace the part number 2526477 diaphragm with part number 323451 diaphragm in accordance with Paragraph 2, Accomplishment Instructions in Pratt & Whitney Aircraft of Canada, Limited, Alert Service Bulletin No. 5153, or approved equivalent parts and procedure. Aircraft may be flown to a base for performance of maintenance required by this AD per FAR 21.197. Any equivalent parts and procedure must be approved by the Chief, Engineering and Manufacturing Branch, of the Eastern Region of the Federal Aviation Administration (FAA). This amendment is effective August 31, 1978. FOOTER:
Document Text
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AD Final Rules - DRS_78-17-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 78-17-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED Model PT6T-3 and PT6T-6 Engines Subject: Automatic Fuel Control Unit Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 08/31/1978 Make: Pratt & Whitney Canada Corp. Model: PT6T-3 | PT6T-3A | PT6T-6 Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 78-17-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3285 AD NUMBER: 78-17-05 SUBJECT HEADING: PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED Model PT6T-3 and PT6T-6 Engines ACTION: SUMMARY: DATES: Effective August 31, 1978. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 78-17-05 PRATT & WHITNEY AIRCRAFT OF CANADA, LIMITED: Amendment 39-3285. Applies to all Pratt & Whitney Aircraft of Canada, Limited PT6T-3 and PT6T-6 turboshaft engines with automatic fuel control with Aviation Electric Ltd. Parts List 2524381-5, 3244712-1 and -2, 3244717-1 through -5, 3244721-1 through -5, 3244735-1 through -7 and 3244737-1 through -7. Compliance required within the next 50 hours in service, after the effective date of this AD, unless already accomplished. To preclude rupture of the bypass valve diaphragm in the automatic fuel control unit, replace the part number 2526477 diaphragm with part number 323451 diaphragm in accordance with Paragraph 2, Accomplishment Instructions in Pratt & Whitney Aircraft of Canada, Limited, Alert Service Bulletin No. 5153, or approved equivalent parts and procedure. Aircraft may be flown to a base for performance of maintenance required by this AD per FAR 21.197. Any equivalent parts and procedure must be approved by the Chief, Engineering and Manufacturing Branch, of the Eastern Region of the Federal Aviation Administration (FAA). This amendment is effective August 31, 1978. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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Related Airworthiness Directives
79-11-03
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