AD 74-15-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | JT3D-1 | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-1-MC6 | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-1-MC7 | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-1A | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-1A-MC6 | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-1A-MC7 | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-3 | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-3B | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-3C | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-5A | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-7 | PRATT & WHITNEY Model JT3D Engines |
| engine | Pratt & Whitney Division | JT3D-7A | PRATT & WHITNEY Model JT3D Engines |
Unsafe Condition
14th stage compressor discs, P/N 657814, may exceed cyclic life limits leading to disc failure.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove from service 14th stage compressor discs prior to exceeding the revised life limits (JT3D-1: 10,000 cycles; JT3D-3B/JT3D-7: 8,000 cycles) or within 25 cycles after the effective date (July 25, 1974), whichever comes later. Discs used in multiple engine models must adhere to the lowest cycle life limit.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
within 25 cycles in service after the effective date of this airworthiness directive whichever comes later
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Pratt & Whitney Model JT3D engines with 14th stage compressor disc P/N 657814, including models JT3D-1, JT3D-3B, and JT3D-7.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Compressor Discs
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_74-15-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 74-15-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: PRATT & WHITNEY Model JT3D Engines Subject: Compressor Discs Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 07/25/1974 Make: Pratt & Whitney Division Model: JT3D-1 | JT3D-1-MC6 | JT3D-1-MC7 | JT3D-1A | JT3D-1A-MC6 | JT3D-1A-MC7 | JT3D-3 | JT3D-3B | JT3D-3C ...Show more 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: 74-15-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1898 AD NUMBER: 74-15-05 SUBJECT HEADING: PRATT & WHITNEY Model JT3D Engines ACTION: SUMMARY: DATES: Effective July 25, 1974. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 74-15-05 PRATT & WHITNEY: Amendment 39-1898. Applies to all Pratt & Whitney Aircraft JT3D turbofan engines containing 14th stage compressor disc, P/N 657814. Compliance required as indicated. To ensure adequate life limit margin for 14th stage compressor discs, P/N 657814, the cyclic life limits on these discs have been reduced below the figures currently approved. Unless already accomplished, remove from service 14th stage compressor discs prior to exceeding the revised life limit listed below or within the next 25 cycles in service after the effective date of this airworthiness directive whichever comes later. Engine Model Previous Life Limit (Cycles) Revised Life Limit (Cycles) JT3D-1 19,000 10,000 JT3D-3B 15,000 8,000 JT3D-7 15,000 8,000 If a disc has been used in more than one engine model, the disc is limited to the lowest cycle life permitted for the engine models in which it has been exposed. This amendment becomes effective July 25, 1974. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_74-15-05.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 74-15-05 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: PRATT & WHITNEY Model JT3D Engines Subject: Compressor Discs Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 07/25/1974 Make: Pratt & Whitney Division Model: JT3D-1 | JT3D-1-MC6 | JT3D-1-MC7 | JT3D-1A | JT3D-1A-MC6 | JT3D-1A-MC7 | JT3D-3 | JT3D-3B | JT3D-3C ...Show more 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: 74-15-05 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1898 AD NUMBER: 74-15-05 SUBJECT HEADING: PRATT & WHITNEY Model JT3D Engines ACTION: SUMMARY: DATES: Effective July 25, 1974. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 74-15-05 PRATT & WHITNEY: Amendment 39-1898. Applies to all Pratt & Whitney Aircraft JT3D turbofan engines containing 14th stage compressor disc, P/N 657814. Compliance required as indicated. To ensure adequate life limit margin for 14th stage compressor discs, P/N 657814, the cyclic life limits on these discs have been reduced below the figures currently approved. Unless already accomplished, remove from service 14th stage compressor discs prior to exceeding the revised life limit listed below or within the next 25 cycles in service after the effective date of this airworthiness directive whichever comes later. Engine Model Previous Life Limit (Cycles) Revised Life Limit (Cycles) JT3D-1 19,000 10,000 JT3D-3B 15,000 8,000 JT3D-7 15,000 8,000 If a disc has been used in more than one engine model, the disc is limited to the lowest cycle life permitted for the engine models in which it has been exposed. This amendment becomes effective July 25, 1974. 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
99-01-08
final ruleAirworthiness Directives; Pratt & Whitney JT8D and JT3D Series Turbofan Engines
Unsafe Condition: Stage 7 through Stage 15 High-Pressure Compressor (HPC) Disks
96-23-10
final ruleAirworthiness Directives; Pratt & Whitney JT3D Series Turbofan Engines
Unsafe Condition: Steel high pressure compressor (HPC) disk failure due to corrosion could result in an uncontained engine failure and damage to the aircraft.
82-14-02
final rulePRATT & WHITNEY AIRCRAFT Model JT3D Engines
Unsafe Condition: Cracks in third stage turbine disks (P/Ns 418903, 438903, and 675803) could result in fracture of the third stage turbine disk and an uncontained third stage turbine disk failure.
80-19-03
final rulePRATT & WHITNEY AIRCRAFT Model JT3D-1-MC7 Engines
Unsafe Condition: High cycle fatigue cracking of fifth stage compressor disks (P/N 426505) which could result in disk fracture.