71 Pa. Stat. § 1451
Whenever a difference arises between an employer and his employés, which cannot be readily adjusted, the chief of the bureau shall proceed promptly to the locality thereof, and endeavor by mediation to effect an amicable settlement of the controversy. If such settlement cannot be effected, the dispute may be arbitrated by a board composed of one person selected by employer, and one person selected by employés, and a third who shall be selected by the representatives of the employer and the employés; and such third member of the board shall be selected and appointed within a period of five days after the matter has been submitted for arbitration, and, in the event of any such appointment or selection not being made within a period of five days, then the Chief of the Bureau of Mediation and Arbitration shall constitute the third member of the board, and be the chairman of the board; and if such third representative is chosen, by the two representatives of the employer and employé, within five days, then a chairman of the board shall be established by the board itself. A submission to the board shall be made in writing, and the parties thereto shall agree to abide by the determination of the board. Said board shall render a written decision within ten days after the completion of the investigation, one copy thereof to be filed in the bureau, and a copy to be furnished each party to the controversy. The chief of the bureau shall make an annual report of his work, containing such information as the Commissioner of Labor and Industry may request.
71 P.S. § 1451