PA-31T/​42Cheyenne

Failure of the fuel control drive can damage the engine and airplane. The AD requires dimensional inspections of the affected fuel control drives at 100-hour intervals and insertion of certain airplane operating procedures into flight manuals.

Engine models named TPE331-1, TPE331-10, TPE331-10AV, TPE331-10GP, TPE331-10GT, TPE331-10P, TPE331-10R, TPE331-10T, TPE331-10U, TPE331-10UA, TPE331-10UF, TPE331-10UG

Cracks have been found in 2nd stage compressor impellers in certain Honeywell turboprop and turboshaft engines, which could lead to impeller failure and uncontained part release. This AD requires removal of the affected 2nd stage compressor impeller.

Engine models named TPE331-10, TPE331-10AV, TPE331-10GP, TPE331-10GT, TPE331-10N, TPE331-10P, TPE331-10R, TPE331-10T, TPE331-10U, TPE331-10UA, TPE331-10UF, TPE331-10UG

Certain Pratt & Whitney Canada turboprop engines have Woodward fuel control units with two-ply Cu-Be bellows that can corrode and perforate, potentially causing engine failure and in-flight shutdown. This AD requires removing affected Woodward FCUs and installing eligible replacement units.

Engine models named PT6A-60AG, PT6A-65AG, PT6A-67AF, PT6A-67AG

Certain engine propeller shaft couplings can fail, causing unexpected propeller pitch changes and increased asymmetric drag on the aircraft. This AD requires removing affected couplings from service and inserting applicable operating procedures into flight manuals.

Engine models named TPE331-10, TPE331-10R, TPE331-10U, TPE331-10UF, TPE331-10UG, TPE331-10UGR, TPE331-10UR, TPE331-5, TPE331-5A, TPE331-5AB, TPE331-5B

Loss of fuel control drive in certain Honeywell turboprop engines can cause engine overspeed, overtorque, overtemperature, uncontained rotor failure, and asymmetric thrust in multi-engine aircraft. Owners must perform initial and repetitive dimensional inspections of the fuel control drive and insert certain operating procedures into flight manuals.

Engine models named TPE331-1, TPE331-10, TPE331-10AV, TPE331-10GP, TPE331-10GT, TPE331-10P, TPE331-10R, TPE331-10T, TPE331-10U, TPE331-10UA, TPE331-10UF, TPE331-10UG

Compressor turbine blades in certain PT6A engines can fail, potentially damaging the engine and aircraft. The AD requires borescope inspections of compressor turbine blades and removal of any blades that fail inspection.

Engine models named PT6A-114, PT6A-114A

Certain Timken Alcor Aerospace Technologies first stage sun gears and planet gears in the reduction gearbox can fail, causing in-flight engine shutdown and possible uncontained failure. Remove these affected parts from service.

Engine models named PT6A-110, PT6A-112, PT6A-114, PT6A-114A, PT6A-121, PT6A-135, PT6A-135A, PT6A-38, PT6A-41, PT6A-42, PT6A-42A, PT6A-61

A first stage turbine disk with a metallurgical defect fractured in an uncontained manner, risking damage to the engine and aircraft. This AD requires inspection of affected turbine disks to prevent uncontained failure.

Engine models named TPE331-10, TPE331-10AV, TPE331-10GP, TPE331-10GT, TPE331-10N, TPE331-10P, TPE331-10R, TPE331-10T, TPE331-10U, TPE331-10UA, TPE331-10UF, TPE331-10UG

Certain Timken Alcor Aerospace Technologies replacement sun gears and planetary gear sets in the propeller reduction gearbox may fail, causing engine in-flight shutdown and possible uncontained engine failure. This AD requires removal of affected TAATI PMA replacement first stage reduction sun gears and/or interacting planetary gear sets.

Engine models named PT6A-15AG, PT6A-27, PT6A-28, PT6A-34, PT6A-34AG, PT6A-34B, PT6A-36

Certain PMA replacement first stage reduction sun gears from Timken Alcor Aerospace Technologies have failed in service. This AD requires removal of affected TAATI first stage reduction sun gears and interacting planet gears from the propeller reduction gearbox assembly.

Engine models named PT6A-15AG, PT6A-27, PT6A-28, PT6A-34, PT6A-34AG, PT6A-34B, PT6A-36

Certain Dixie Aerospace LLC main shaft bearings installed in Honeywell TPE331 turboprop engines are unsafe. This AD requires inspection of airplane records to confirm if the affected bearing is installed and removal from service before further flight.

Engine models named TPE331

Certain first stage turbine disks in TPE331-10 and TPE331-11 series engines have metallurgical defects that can cause uncontained failure. This AD requires removing affected first stage turbine disks from service.

Engine models named TPE331-10 series, TPE331-11 series

Certain Honeywell turboprop and turboshaft engines have experienced uncontained turbine rotor separation due to low-cycle fatigue, particularly in special-use operations with multiple takeoffs and landings without shutdown. This AD requires implementing a new flight cycle counting method for first, second, and third-stage turbine rotors and removing rotors from service when they reach their cycle life limits.

Engine models named TPE331 series

Woodward propeller governor assemblies on certain PT6A-60A and PT6A-65B engines can cause difficult directional control during landing. This AD requires replacing the affected governor assemblies.

Engine models named PT6A-60A, PT6A-65B

First stage turbine disks in TPE331-10 and -11 series engines may develop cracks from melt-related defects that could cause uncontained disk separation and engine damage. This AD requires initial and repetitive fluorescent penetrant and eddy current inspections of affected disks.

Engine models named TPE331-10, TPE331-11

Weld-repaired first stage compressor impellers have failed in service, causing uncontained engine failures and in-flight shutdowns. This AD requires removing all weld-repaired first stage Ti 6-4 compressor impellers from service.

Engine models named TPE331-10, TPE331-11, TPE331-3, TPE331-5, TPE331-6, TPE331-8

Cracks have been found along weld seams in certain turbine exhaust ducts on PT6A engines that were modified by various companies. This AD requires inspections for low-quality welds and cracks to prevent separation of the reduction gearbox and propeller from the engine.

Engine models named PT6A series

Second stage turbine stator assemblies may have obstructed cooling holes or passages that cause contact and rub into the turbine rotor, potentially resulting in uncontained turbine wheel separation. This AD requires replacement of affected second stage turbine stator assemblies with serviceable units.

Engine models named TPE331-1, TPE331-2, TPE331-2UA, TPE331-3U, TPE331-3UW, TPE331-5, TPE331-5A, TPE331-5AB, TPE331-5B, TPE331-6, TPE331-6A

Bull gear rim separations and high-speed pinion assembly failures can occur due to abnormal gear wear, potentially causing uncontained gearbox fragmentation and engine failures. The AD requires repetitive oil analysis sampling, trend assessment, and inspection and replacement of certain gearbox components.

Engine models named TPE331-11U, TPE331-12B, TPE331-12JR, TPE331-12UA, TPE331-12UAR, TPE331-12UHR

Certain TPE331 turboprop engines with specific electronic engine controls can experience uncommanded full power increases, risking loss of airplane control due to asymmetric thrust. Operators must revise their Airplane Flight Manual Emergency and Normal Procedures sections until the affected engine controls are replaced.

Engine models named TPE331-10N, TPE331-12B, TPE331-8

Pratt & Whitney Canada PT6A-25C and -114A engines may experience wear in the compressor bleed valve assembly causing power loss or in-flight shutdown. The AD requires initial and repetitive visual inspections and eventual replacement of the compressor bleed valve assembly with a redesigned version.

Engine models named PT6A-114A, PT6A-25C

Fuel manifold assemblies repaired by Hoses Unlimited may have defective fittings that could leak fuel onto hot turbine components and cause an engine fire. Operators must remove suspect fuel manifolds and replace them with serviceable assemblies.

Engine models named TPE331-10, TPE331-11, TPE331-12, TPE331-8

Cracks have been found in third stage turbine stators due to thermal fatigue, which could lead to turbine wheel separation and an uncontained engine failure. This AD requires replacement or radiographic inspection and replacement if necessary of affected turbine stators.

Engine models named TPE331-1, TPE331-2, TPE331-2UA, TPE331-3U, TPE331-3UW, TPE331-5, TPE331-5A, TPE331-5AB, TPE331-5B, TPE331-6, TPE331-6A

Icing of the inlet Pt2 sensor in TPE331 engines can cause erroneous pressure signals leading to non-responsive power lever movement. This AD requires revising emergency procedures in the AFM/POH and replacing or reworking orifice fittings and restrictors to prevent loss of engine power control.

Engine models named TPE331-10, TPE331-11, TPE331-12, TPE331-3, TPE331-5, TPE331-6

Some TPE331 and TSE331 engines were repaired or maintained by Fliteline Maintenance (a shop in Texas) or specific individuals who performed substandard work, risking turbine failures and engine fires. Operators must search engine records to identify any engines serviced by Fliteline, verify all life-limited components, and inspect affected parts to ensure compliance with applicable directives.

Engine models named TPE331 series

Pratt & Whitney Canada PT6A-67D engines installed on Beech 1900D aircraft may experience cracking in compressor turbine components. After installation of improved engine components, owners must remove the engine RPM operating restriction placard and revert the Airplane Flight Manual to its original state.

Engine models named PT6A-67D