AD 91-05-21
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | General Electric Company | CF6-80C2A5 | GENERAL ELECTRIC COMPANY Models CF6-80C2A5 and CF6-80C2B6 Engines |
| engine | General Electric Company | CF6-80C2B6 | GENERAL ELECTRIC COMPANY Models CF6-80C2A5 and CF6-80C2B6 Engines |
| engine | General Electric Company | CF6-80C2B6F | GENERAL ELECTRIC COMPANY Models CF6-80C2A5 and CF6-80C2B6 Engines |
| engine | General Electric Company | CF6-80C2D1F | GENERAL ELECTRIC COMPANY Models CF6-80C2A5 and CF6-80C2B6 Engines |
Unsafe Condition
High Pressure Turbine (HPT) failure and possible aircraft damage due to insufficient shroud cooling design features.
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Required Actions
Borescope inspect engines according to GE SB 72-473 based on cycles since new (CSN). Replace HPT stator assemblies and shrouds per GE SB 72-474 by December 31, 1994. Define HPT module exposure and shroud categories as specified.
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Compliance Time
Within 10 cycles in service (CIS) after the effective date or prior to specified CSN limits, with removal or reinspection intervals based on shroud categories. Replace components by December 31, 1994.
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Affected Aircraft
General Electric CF6-80C2A5, CF6-80C2B6, CF6-80C2B6F, CF6-80C2D1F engines with serial numbers 690-101 through 690-369, 695-101 through 695-423, 702-101 through 702-470, and 703-101 through 703-136, without the improved shroud cooling design.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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