On August 25, 2000, a Hughes 369E (registration N570CA) was involved in an aviation accident near Coolin, ID. Investigators recorded the probable cause as: The engine failures and stress ruptures were a result of high temperature engine operation above 2000°F. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An engine lost power shortly after takeoff, leading to an emergency running landing. During landing, main rotor blades severed the tail boom. Inspection revealed an under-reading TOT gauge and engine damage from high-temperature operation.
Accident Overview
Shortly after takeoff, the engine experienced a loss of power. The pilot initiated an emergency running landing. During the landing phase, the main rotor blades contacted and subsequently severed the tail boom.
Inspection Findings
The engine and associated components were inspected. The turbine outlet temperature (TOT) indicating system was examined to verify its calibration. The TOT system is required to be calibrated during all 300-hour inspections. Testing revealed that the cockpit TOT gauge indicated temperatures lower than the actual engine outlet temperatures. This discrepancy may have led to multiple operations being conducted at temperatures exceeding those authorized by the Pilot's Flight Manual and the engine manufacturer's limitations.
Engine Examination
A teardown inspection of the engine confirmed that the failures and stress ruptures found throughout the engine turbine assembly components were a result of high temperature engine operation above 2000°F.
Probable cause
The engine failures and stress ruptures were a result of high temperature engine operation above 2000°F.