How many hours must be completed on solo flights or with an instructor for the commercial multi add-on?

For the commercial multi-engine add-on, the requirement is to complete a minimum of 10 hours of flight time that is specifically focused on multi-engine proficiency. This can be achieved through solo flights or while flying with an instructor.

This requirement ensures that pilots have adequate exposure and experience in handling the unique characteristics of multi-engine aircraft, including performance issues like engine failures, which are critical for safety and competency in commercial operations. By specifying 10 hours, the regulation emphasizes the importance of a thorough understanding and practice in multi-engine flight before obtaining the add-on rating.