It is 25% of the hours in the 141 syllabus. Total Time: 120 (part 141) equals can count 30 of your part 61 hours. Same is true for the rest of the requirements PIC, night, IFR, ect. You take what they have and can give them 25% toward their 141 syllabus. We offer commercial training with your initial class being multi engine. So we have alot of single engine add ons done in three hours. The way it works is they are training as a commercial single until 105 hours in course. The last 15 hours of the syllabus are in the multi. Thus only needing 3 hours in 60 days under 61 to do their single engine add on.