Airworthiness Directive · Amendment 39-13775 · Pratt & Whitney Canada PW206A and PW206E Turboshaft Engines
Pratt & Whitney Canada PW206A and PW206E Turboshaft Engines
This AD applies to Pratt & Whitney Canada (PWC) PW206A and PW206E turboshaft engines. These engines are installed on, but not limited to, MD Helicopters, Inc. Model MD-900 helicopters.
The FAA is superseding an existing airworthiness directive (AD) for Pratt & Whitney Canada (PWC) PW206A and PW206E turboshaft engines. That AD currently requires: <bullet> Initial and repetitive borescope inspections of compressor turbine and power turbine blades for blade axial shift. <bullet> 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 of engine shutdowns and emergency landings due to severe vibration, resulting in exhaust gases escaping from the engine-to-exhaust nozzle interface, thereby triggering in-flight engine fire warnings. We are issuing this AD to prevent turbine blade axial shift, which could cause high levels of vibration, loss of engine torque, in-flight engine shutdown, and loss of the airframe exhaust duct.
You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.
Perform an initial sequence of borescope inspections of compressor turbine blades and power turbine blades for blade axial shift within the turbine disks. Use paragraph 3. of Accomplishment Instructions of PWC Alert Service Bulletin (ASB) No. PW200-72-A28242, Revision 1, dated October 2, 2002, for the borescope inspection and determination of blade shift. Do the inspections at the following times:
(1) Within 25 flight hours accumulated, or 30 days after the effective date of this AD, whichever occurs earlier.
(2) After 30 flight hours, but before 50 flight hours accumulated since inspection of paragraph (f)(1) of this AD.
(3) After 80 flight hours, but before 100 flight hours accumulated since inspection of paragraph (f)(1) of this AD.
(4) After 180 flight hours, but before 200 flight hours accumulated since inspection of paragraph (f)(1) of this AD.
Thereafter, perform repetitive borescope inspections at intervals of not less than 280 nor more than 300 flight hours since-last-inspection. Use paragraph 3. of Accomplishment Instructions of PWC ASB No. PW200-72-A28242, Revision 1, dated October 2, 2002, for the borescope inspections and determination of blade shift.
If you find any blade shift, remove engine from service before further flight and perform rivet and rotor air seal replacements, as specified in paragraphs (i)(1) through (i)(3) of this AD, to return the engine to service.
(i) At the next engine shop visit when access is available to subassemblies, such as modules, accessories, and components, or at the next engine overhaul, whichever occurs first, but before accumulating 1,800 flight hours from the effective date of this AD or before December 31, 2009, whichever occurs first, do the following:
(1) Replace the compressor turbine blade retaining rivets with new P/N retaining rivets, and the No. 4 bearing rear rotor air seal with the new P/N No. 4 bearing rear rotor air seal. Use paragraph 3., Part A, of Accomplishment Instructions of SB No. PW200-72-28069, Revision 5, dated February 10, 2003.
(2) Replace the No. 3 bearing rotating air seal with the new P/N air seal, and the No. 4 bearing front rotor air seal with the new P/N No. 4 bearing front rotor air seal. Use paragraph 3., Part B, of Accomplishment Instructions of SB No. PW200-72-28069, Revision 5, dated February 10, 2003.
(3) Replace the power turbine blade retaining rivets with new P/N power turbine blade retaining rivets. Use paragraph 3. of Accomplishment Instructions of SB No. PW200-72-28239, Revision 2, dated February 10, 2003.
(j) Completing the actions in paragraphs (i)(1) through (i)(3) of this AD terminates all inspection requirements of this AD.
Previous credit is allowed:
(1) For performing the initial sequence for borescope inspections in paragraph (f) of this AD, that were done using AD 2003-16-10.
(2) For terminating action in paragraphs (i)(1) through (i)(3) of this AD that was done using the Accomplishment Instructions of one of the following, before the effective date of this AD:
(i) SB No. PW200-72-28069, dated June 10, 1997
(ii) SB No. PW200-72-28069, Revision 1, dated September 8, 1997
(iii) SB No. PW200-72-28069, Revision 2, dated December 18, 1997
(iv) SB No. PW200-72-28069, Revision 3, dated November 30, 1998
(v) SB No. PW200-72-28069, Revision 4, dated December 27, 2000
(vi) SB No. PW200-72-28069, Revision 5, dated February 10, 2003
(vii) SB No. PW200-72-28239, dated September 5, 2002
(viii) SB No. PW200-72-28239, Revision 1, dated December 5, 2002
(ix) SB No. PW200-72-28239, Revision 2, dated February 10, 2003
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
