AD 66-21-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | JT3C-12 | PRATT & WHITNEY Model JT3C-7 and JT3C-12 Engines |
| engine | Pratt & Whitney Division | JT3C-7 | PRATT & WHITNEY Model JT3C-7 and JT3C-12 Engines |
Unsafe Condition
The first, fifth, and sixth stage compressor rotor disc spacer assemblies (P/N 359410, 359414, and 359415) may fail due to insufficient strength, leading to engine failure.
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Required Actions
Replace the first, fifth, and sixth stage compressor rotor disc spacer assemblies with new spacer assemblies P/N 460599, 460604, and 460606 respectively. Compliance must be completed within the next 6,000 hours' time in service after the effective date or at the next compressor disassembly, whichever occurs first.
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Compliance Time
within the next 6,000 hours' time in service after the effective date of this AD or at the next compressor disassembly, whichever occurs first
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Pratt & Whitney Model JT3C-7 and JT3C-12 engines
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Federal Register Abstract
Rotor Disc Spacer Assemblies
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_66-21-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 66-21-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: PRATT & WHITNEY Model JT3C-7 and JT3C-12 Engines Subject: Rotor Disc Spacer Assemblies Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 09/30/1966 Make: Pratt & Whitney Division Model: JT3C-12 | JT3C-7 Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 66-21-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-279 AD NUMBER: 66-21-01 SUBJECT HEADING: PRATT & WHITNEY Model JT3C-7 and JT3C-12 Engines ACTION: SUMMARY: DATES: Effective September 30, 1966. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 66-21-01 PRATT & WHITNEY: Amdt. 39-279 Part 39 Federal Register August 31, 1966. Applies to Model JT3C-7 and JT3C-12 Turbojet Engines. Compliance required as indicated. Within the next 6,000 hours' time in service after the effective date of this AD or at the next compressor disassembly, whichever occurs first, unless already accomplished, replace the first, fifth and sixth stage compressor rotor disc spacer assemblies, P/N's 359410, 359414, and 359415, with spacer assemblies, P/N's 460599, 460604, and 460606, respectively. (Pratt & Whitney Aircraft Turbojet Engine Service Bulletin No. 689, Revision No. 3, dated November 16, 1964, pertains to this subject.) This directive effective September 30, 1966. FOOTER:
Document Text
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AD Final Rules - DRS_66-21-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 66-21-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: PRATT & WHITNEY Model JT3C-7 and JT3C-12 Engines Subject: Rotor Disc Spacer Assemblies Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 09/30/1966 Make: Pratt & Whitney Division Model: JT3C-12 | JT3C-7 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: AIRWORTHINESS DIRECTIVES FINAL RULES: 66-21-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-279 AD NUMBER: 66-21-01 SUBJECT HEADING: PRATT & WHITNEY Model JT3C-7 and JT3C-12 Engines ACTION: SUMMARY: DATES: Effective September 30, 1966. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 66-21-01 PRATT & WHITNEY: Amdt. 39-279 Part 39 Federal Register August 31, 1966. Applies to Model JT3C-7 and JT3C-12 Turbojet Engines. Compliance required as indicated. Within the next 6,000 hours' time in service after the effective date of this AD or at the next compressor disassembly, whichever occurs first, unless already accomplished, replace the first, fifth and sixth stage compressor rotor disc spacer assemblies, P/N's 359410, 359414, and 359415, with spacer assemblies, P/N's 460599, 460604, and 460606, respectively. (Pratt & Whitney Aircraft Turbojet Engine Service Bulletin No. 689, Revision No. 3, dated November 16, 1964, pertains to this subject.) This directive effective September 30, 1966. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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Related Airworthiness Directives
66-16-06
final rulePRATT & WHITNEY Models JT3C-7 and JT3C-12 Engines
Unsafe Condition: Failure of fourth stage compressor rotor disc spacer assemblies due to cracks in visible areas of the spacer.
64-05-05
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Unsafe Condition: Throttle valve packing leakage in Hamilton Standard JFC25 engine fuel controls could cause severe engine damage.
62-09-04
final rulePRATT & WHITNEY Models JT3C- 7 and JT3C-12 Engines
Unsafe Condition: Fatigue cracking has occurred in the dovetail attachment of part number 359403 third stage compressor rotor blades.
62-17-06
final rulePRATT & WHITNEY Model JT3C-12 Engines
Unsafe Condition: Fatigue cracking in the rear face of the P/N 359708 eighth stage compressor rotor disc.