5. If the arbitral tribunal is composed of more than one arbitrator, it shall be authorised to designate one of its members to examine witnesses. In such case a written report of the examination of the witnes­ses shall be made.

Article 30 - Experts (Party-Appointed)

A party shall be free to submit the opinion of an expert consulted by him. If the party submitting the expert opinion or the other party so requires, or if the arbitral tribunal so determines, the party submitting the opinion shall call the expert to appear at a hearing to further explain his opinion, unless the arbitral tribunal shall determine a different method of calling such expert witness.   

Article 31 - Experts (Tribunal-Appointed)