AD/PT6A/27 - Compressor Bleed Off Valve
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
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Pratt and Whitney Canada Turbine Engines - PT6A Series
AD/PT6A/27 Compressor Bleed Off Valve 4/97
Applicability: All Pratt and Whitney Canada (PWC) PT6A engines as detailed by serial number in the following PWC Service Bulletins (SB): SB 1538 Rev.3; SB 3344 Rev.1; SB 4204; SB 12134 Rev.1; SB13287 Rev.1; SB 14251 Rev.1.
Requirement: To prevent the possible malfunction of the compressor bleed off valve resulting in a reduction of required engine power or an engine surge event:
Inspect the bleed off valve to determine the supplier code. If the supplier code is “8070”, inspect the bleed off valve in accordance with PWC SB 1538 Rev. 3; SB 3344 Rev.1; SB 4204; SB 12134 Rev.1; SB 13287 Rev.1 or SB 14251 Rev.1 as applicable by engine model.
2. If the supplier code is not “8070” or the bleed off valve has been re-identified to “RE71”, no further action is required.
Note: Transport Canada Airworthiness Directive CF-96-24 refers.
Compliance: Effective 27 March 1997: Unless previously accomplished; within 100 hours time in service or prior to 30 May 1997, whichever occurs first.
Background: This directive has been issued to require certain compressor bleed off valves to be inspected. The requirement follows advice of movement in the valve guide shaft pin can result in fracture of the cotter pin and possible jamming of the valve. Failure of the valve may result in the loss of required engine power or an engine surge.