(1) Unless otherwise agreed by the parties, the arbitral tribunal:

(a) May appoint one or more experts to report to it on specific issues to be determined by the arbitral tribunal;

(b) May require a party to give the expert relevant information or to produce, or to provide access to, relevant documents, goods or other property for his inspection.

(2) Unless otherwise agreed by the parties, if a party so requests or if the arbitral tribunal considers it necessary, the expert shall, after delivery of his written or oral report, participate in a hearing where the parties have the opportunity to put questions to him and to present expert witnesses in order to testify on the points at issue.