AD 97-12-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | General Electric Company | GE90-76B | Airworthiness Directives; General Electric Company GE90 Series Turbofan Engines |
| engine | General Electric Company | GE90-77B | Airworthiness Directives; General Electric Company GE90 Series Turbofan Engines |
| engine | General Electric Company | GE90-85B | Airworthiness Directives; General Electric Company GE90 Series Turbofan Engines |
| engine | General Electric Company | GE90-90B | Airworthiness Directives; General Electric Company GE90 Series Turbofan Engines |
Unsafe Condition
Failure of the Variable Speed Constant Frequency (VSCF) gearshaft flange ball bearing, Part Number 1770M41P01, due to improper rivet material and insufficient internal radial clearances causing excessive ball to cage pocket forces leading to bearing distress and premature failure.
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Required Actions
Within 24 hours after the effective date, perform a visual check of the engine Debris Monitoring System (DMS) sensor for bearing debris and perform additional maintenance actions if necessary. Thereafter, conduct staggered daily visual checks of the DMS sensor every other day. Replace VSCF gearshaft flange ball bearings with improper rivet material using serviceable bearings per GE SB No. 72-283, Revision 4 or GE SB No. 72-286.
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Compliance Time
Within 24 hours after the effective date of this AD and thereafter at staggered one day intervals for each affected engine.
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Affected Aircraft
General Electric Company GE90-76B, GE90-77B, GE90-85B, GE90-90B turbofan engines.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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