AD 66-16-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | JT3C-12 | PRATT & WHITNEY Models JT3C-7 and JT3C-12 Engines |
| engine | Pratt & Whitney Division | JT3C-7 | PRATT & 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.
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Required Actions
Drill an inspection hole and install a plug in the compressor case and fourth stage vane and shroud assembly. Inspect the spacer assembly using a specified cystoscope for cracks. Replace cracked spacers with P/N 359413 or 429177 before further flight. Remove engine and reinspect if cracks are found during inspection.
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Compliance Time
Within the next 50 hours' time in service after the effective date, unless already accomplished within the last 575 hours' time in service, and thereafter at intervals not to exceed 625 hours' time in service from the last inspection until installation of assembly P/N 429177.
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Affected Aircraft
Pratt & Whitney Models JT3C-7 and JT3C-12 Turbojet Engines.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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