Airworthiness Directives; General Electric Aircraft Engines CT7 Series Turboprop Engines

The FAA is superseding an existing airworthiness directive (AD) for certain General Electric Aircraft Engines (GEAE) CT7 series turboprop engines. That AD currently requires propeller gearbox (PGB) oil filter impending bypass button (IBB) inspections, oil filter inspections, replacement of left-hand and right-hand idler gears at time of PGB overhaul, and replacement of certain serial number (SN) PGBs before accumulating 2,000 flight hours. This AD requires the same actions, and adds additional SNs of affected PGBs. This AD results from reports of PGBs equipped with certain gears that do not meet design specifications, resulting in the same failure addressed in the existing AD. We are issuing this AD to prevent separation of PGB left-hand and right-hand idler gears, which could result in uncontained PGB failure and internal bulkhead damage, possibly prohibiting the auxiliary feathering system from fully feathering the propeller on certain PGBs.