AD 2005-20-11
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Allison | Engine Company | Airworthiness Directives; Rolls-Royce Corporation (RRC) (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison) Models 250-C28, -C28B, and -C28C Turboshaft Engines |
Unsafe Condition
Compromised third-stage blade fillet radii leading to increased stresses on the third-stage blades and shroud, which could result in failure of the third-stage turbine wheel.
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Required Actions
Inspect the seal joint in each passage between airfoils at the hub and shroud of third-stage turbine wheels, part number 6899383. Remove any turbine wheel with seal joint evidence present within blade fillet radii.
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Compliance Time
Within 300 flight hours or by April 30, 2007, whichever occurs sooner, depending on the time-since-new (TSN) of the turbine wheel.
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Affected Aircraft
Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison) Models 250-C28, -C28B, and -C28C turboshaft engines, installed on Bell Helicopter Textron 206L-1, Eurocopter Deutschland BO 105 LS A-1, and Eurocopter Canada BO 105 LS A-3 helicopters.
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Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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