Airworthiness Directive · Amendment 39-13553 · General Electric Aircraft Engines CT7 Series Turboprop Engines
General Electric Aircraft Engines CT7 Series Turboprop Engines
This AD applies to General Electric Aircraft Engines (GEAE) CT7 series turboprop engines, with propeller gearboxes (PGBs) identified by serial number (SN) in Table 1 of GEAE CT7 Turboprop Service Bulletin (SB) CT7-TP S/B 72-0452, dated July 27, 2001, and Table 1 of GEAE CT7 Turboprop Alert Service Bulletin (ASB) CT7-TP S/ B 72-A0466, dated April 17, 2003. These engines are installed on but not limited to SAAB 340 series airplanes.
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.
