AD NUMBER: 2004-17-03 MANUFACTURER: Pratt & Whitney SUBJECT: Airworthiness Directive 2004-17-03 SUMMARY: The FAA is superseding an existing
airworthiness directive (AD) for Pratt & Whitney Canada (PWC)
PW206A and PW206E turboshaft engines. That AD currently requires:.
Initial and repetitive borescope inspections of compress or turbine
and power turbine blades forblade axial shift.. Replacement of
blade retaining rivets and certain rotor air seals as terminating
action for the repetitive borescope inspections.This ad requires
the same actions as AD 2003-NE-25-AD but the extent of engine
disassembly that triggers the required part replacements needs
clarification. This AD results from reports ofengine shutdowns and
emergency landings due to severe vibration, resulting in exhaust
gases escaping from the engine-to-exhaust nozzle interface, there
by triggering in-flight engine firewarnings. We are issuing this AD
to prevent turbine blade axial shift, which could cause highlevels
of vibration, loss of engine torque, in-flight engine shutdown, and
loss of the airframe exhaust duct.