Cal. Mil. & Vet. Code § 489.3

Whenever a bank or trust company is acting as trustee by reason of any default, or for the protection of the interests of the revenue bondholders, the bank or trust company as such trustee shall take such action as the holders or registered owners of 25 percent in principal amount of all the revenue bonds then outstanding shall request in writing; provided, that the bank or trust company as such trustee may request reasonable security before taking any action so requested.