As long as any trade school is an "eligible educational institution," the 529 funds can be used there without paying tax or the 10% penalty on the earnings portion of any distribution.
Eligible educational institution: For purposes of a QTP, this is any college, university, vocational school, or other postsecondary educational institution eligible to participate in a student aid program administered by the U.S. Department of Education. It includes virtually all accredited public, nonprofit, and proprietary (privately owned profit-making) postsecondary institutions. The educational institution should be able to tell you if it is an eligible educational institution.
The additional 10% tax on the earnings portion of distributions that are not used for qualified education expenses does not apply if the designated beneficiary is disabled.
A person is considered to be disabled if he or she shows proof that he or she can't do any substantial gainful activity because of his or her physical or mental condition. A physician must determine that his or her condition can be expected to result in death or to be of long-continued and indefinite duration.
The language in italics is from IRS pub 970, Tax Benefits for Education.