Systems and methods for identifying insufficient starter acceleration for an aircraft engine

A method for identifying insufficient starter acceleration for an engine start sequence for an aircraft engine, the method comprising:

• initiating the engine start sequence for the aircraft engine, and the engine start sequence includes applying a rotational force to a rotational assembly of the aircraft engine with a starter;
• measuring an engine oil temperature for the aircraft engine;
• determining an acceleration threshold for a starter-assist only phase of the engine start sequence using the measured engine oil temperature;
• measuring an acceleration of the rotational assembly during the starter-assist only phase;
• identifying a presence or an absence of insufficient starter acceleration for the starter-assist only phase by comparing the measured acceleration to the acceleration threshold, the presence of the insufficient starter acceleration is identified when the measured acceleration is less than the acceleration threshold, and the absence of the insufficient starter acceleration is identified when the measured acceleration is greater than the acceleration threshold;
• and
• identifying a cause of the insufficient starter acceleration, during a shutdown sequence for the aircraft engine subsequent to the engine start sequence, by comparing a rundown time for the rotational assembly during the shutdown sequence to a rundown time threshold, the rundown time threshold determined using an air inlet temperature, an altitude, and a measured engine oil temperature, the cause of the insufficient starter acceleration identified as rotational assembly drag when the rundown time is less than the rundown time threshold or as the starter when the rundown time is greater than the rundown time threshold.

An assembly for an aircraft engine, the assembly comprising:

• a rotational assembly including at least one rotor;
• a starter configured to selectively drive rotation of the rotational assembly;
• and
• a controller including a processor in communication with a non-transitory memory storing instructions, which instructions when executed by the processor, cause the processor to:
• determine an acceleration threshold for a starter-assist only phase of an engine start sequence for the aircraft engine;
• measure an acceleration of the rotational assembly during the starter-assist only phase;
• identify a presence of insufficient starter acceleration for the starter-assist only phase by comparing the measured acceleration to the acceleration threshold;
• and
• identify a cause of the insufficient starter acceleration, in response to identification of the presence of the insufficient starter acceleration, during a shutdown sequence for the aircraft engine, by comparing a rundown time for the rotational assembly during the shutdown sequence to a rundown time threshold;
• wherein the instructions, when executed by the processor, further cause the processor to:
• determine the rundown time threshold using an air inlet temperature, an altitude, and a measured engine oil temperature;
• and
• identify the cause of the insufficient starter acceleration as rotational assembly drag when the rundown time is less than the rundown time threshold or as the starter when the rundown time is greater than the rundown time threshold.