PT6A hot section inspection — what owners should know before sourcing parts
The most expensive scheduled event on a turboprop. Done right, it pays off over thousands of hours.
What a hot section inspection actually does
The PT6A hot section comprises the combustion chamber, the compressor turbine (CT) blades and shroud, the power turbine (PT) blades and shroud, and the surrounding nozzle guide vanes. Pratt & Whitney Canada requires inspection at fixed intervals (usually 1,800–3,600 hours TBO depending on model and operator).
The HSI removes the hot section from the engine, breaks it down, magnafluxes everything, replaces wear items, and reassembles to spec. The engine is reinstalled, run on a test cell, and trim-balanced before return to service.
Parts that always replace
CT blades — compressor turbine blades. Always replaced. Each engine has 41–58 depending on dash number.
NGVs (nozzle guide vanes) — almost always replaced. Wear and erosion is inevitable at hot section temperatures.
Combustion chamber liner — inspected, often replaced if hot-spot erosion exceeds limits.
Bearings — typically the No. 2 and No. 3 bearings get replaced. Bearing #4 sometimes.
Seals, gaskets, and O-rings — all replaced. These are the cheap parts that take hours of labor when they fail.
Parts that sometimes replace
PT blades (power turbine) — inspected, replaced if cracks or hot-spot damage exceed P&WC service bulletin limits.
Shrouds — CT and PT shrouds inspected for clearance and erosion. Often resurfaced rather than replaced.
Magnetic chip detectors / scavenge filters — replaced if metal showed during run-up.
Fuel nozzles — flow-checked. Outliers replaced or rebuilt.
Cost breakdown — what to budget
Labor: typically 80-120 hours of shop time at $130–185/hour depending on facility = $10K–22K.
Parts (no-findings minimum): $40K–60K for CT blades + NGVs + seals + bearings.
Parts (typical findings): $70K–110K.
Parts (worst-case combustion liner + PT blades): $130K–180K.
Used-serviceable parts with trace documents can cut the parts bill by 30-50% on items like NGVs and combustion liners. CT blades almost always replace new — used-CT blade markets are thin.
Where to source PT6A parts
Pratt & Whitney Canada has authorized distributors. Outside the PWC network, the active aftermarket includes Standard Aero, Covington, H+S Aviation, and dozens of smaller surplus dealers.
Used-serviceable trace parts — particularly NGVs, combustion liners, and shrouds — show up on Haven Jet Parts regularly. Listings flag the issuing organization's cert and the work tag (overhauled vs. inspected/tested). Filter by 8130-3 Available to skip the back-and-forth.
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