Electric starter verification during gas-turbine engine barring

1. A system comprising:

a first gas-turbine engine configured to propel an aircraft, the first gas-turbine engine comprising a first electric starter, the first electric starter configured to rotate a spool of the first gas-turbine engine; and

one or more controllers collectively configured to:

cause, following operation of the first gas-turbine engine, the first electric starter to perform barring of the first gas-turbine engine;

measure, during the barring of the first gas-turbine engine, values of one or more parameters of the first gas-turbine engine; and

determine, based on the values of the one or more parameters, whether the first electric starter is available for use in performing mid-air restart of the first gas-turbine engine.

2. The system of claim 1 , wherein the one or more parameters of the first gas-turbine engine include a rotational speed of the spool of the first gas-turbine engine.

3. The system of claim 2 , wherein, to determine whether the first electric starter is available for use in performing mid-air restart of the first gas-turbine engine, the one or more controllers are configured to:

responsive to determining that the rotational speed of the spool of the first gas-turbine engine is greater than a threshold rotational speed, determine that the first electric starter is available for use in performing mid-air restart of the first gas-turbine engine.

4. The system of claim 1 , wherein the one or more controllers comprise:

a motor controller; and

an electronic engine controller (EEC).

5. The system of claim 4 , wherein, during a shutdown procedure of the EEC, the EEC is configured to transfer control authority over the electric starter to the motor controller, and wherein, responsive to receiving the control authority, the motor controller is configured to cause the first electric starter to perform the barring of the first gas-turbine engine.

6. The system of claim 5 , wherein, during the barring, the motor controller is configured to:

measure the values of one or more parameters of the first gas-turbine engine; and

determine, based on the values of the one or more parameters, whether the first electric starter is available for use in performing mid-air restart of the first gas-turbine engine.

7. The system of claim 6 , wherein the motor controller is further configured to determine that the barring is complete and cease causing the first electric starter to perform the barring of the first gas-turbine engine responsive to determining that one or more barring completion criterion have been met.

8. The system of claim 7 , wherein, responsive to receiving a control interrupt from the EEC, the motor controller is configured to surrender the control authority over the electric starter to the EEC.

9. The system of claim 7 , wherein, responsive to receiving a control interrupt from the EEC, the motor controller is further configured to output an indication of whether the first electric starter is available for use in performing mid-air restart of the first gas-turbine engine.

10. The system of claim 7 , wherein the motor controller receives the controller interrupt prior to determining that the one or more barring completion criterion have been met.

11. An airframe comprising the system of claim 1 .

12. The system of claim 1 , wherein the one or more controllers are collectively configured to:

output an indication whether or not the first electric starter is available for use in performing mid-air restart of the first gas-turbine engine.

13. The system of claim 1 , wherein the one or more controllers are collectively configured to:

perform the mid-air restart of the first gas-turbine engine by at least causing the first electric starter to rotate the spool while fuel is introduced into a combustion chamber of the first gas-turbine engine.