Final answer:
If you get an AC pack disagreement during engine start, you should identify the cause and troubleshoot the aircraft's electrical system. Potential causes include faulty sensors or wiring, as well as software or firmware mismatches. If the issue persists, consult the maintenance manual or a licensed engineer.
Step-by-step explanation:
If you encounter an AC pack disagreement during engine start, the first step is to identify the cause of the disagreement. This can be done by examining the aircraft's electrical system and troubleshooting any potential issues. One possible cause of an AC pack disagreement is a faulty sensor or wiring. In this case, the sensor or wiring should be repaired or replaced.
Another possible cause of an AC pack disagreement is a mismatch in the software or firmware of the AC packs. It is important to ensure that the software or firmware of the AC packs is up-to-date and compatible with each other.
If the AC pack disagreement persists after troubleshooting, it is recommended to consult the aircraft's maintenance manual or contact a licensed aircraft maintenance engineer for further assistance.