"
...can the type rating be done on a B1 visitors visa...?"
No, see the memo linked in post #255. Initial training that could lead to certification requires a student visa unless already admitted into the US under another qualifying visa or status. See ICE's guide,
Nonimmigrants: Who Can Study?
8 CFR 214.2(b)(7)
Enrollment in a course of study prohibited. An alien who is admitted as, or changes status to, a B-1 or B-2 nonimmigrant on or after April 12, 2002, or who files a request to extend the period of authorized stay in B-1 or B-2 nonimmigrant status on or after such date, violates the conditions of his or her B-1 or B-2 status if the alien enrolls in a course of study. Such an alien who desires to enroll in a course of study must either obtain an F-1 or M-1 nonimmigrant visa from a consular officer abroad and seek readmission to the United States, or apply for and obtain a change of status under section 248 of the Act and 8 CFR part 248. The alien may not enroll in the course of study until the Service has admitted the alien as an F-1 or M-1 nonimmigrant or has approved the alien's application under part 248 of this chapter and changed the alien's status to that of an F-1 or M-1 nonimmigrant.
9 FAM 402.5-5(J)(7) (U) Aviation Training
(CT:VISA-1970; 04-22-2024)
a. (U) All flight training for initial training or subsequent training that will result in a certificate or rating must be undertaken on an F or M visa. This includes FAA, EASA, and other equivalent certificates.
b. (U) Recurrent or refresher training (training related to an aircraft for which the applicant has already received certification) may be undertaken on a B-1. Recurrent training is the training required for crewmembers to remain adequately trained and currently proficient for each aircraft crewmember position, and type of operation in which the crewmember serves. It often consists of flight simulator training but may also entail classroom training to update pilots on such things as recent safety issues, trends in aviation, and modifications to aircraft configuration or operating procedures. This assumes that the applicant’s employer is covering the recurrent training costs, incidental costs, and that the applicant does not receive a salary or perform labor in the United States.