Letters testamentary or of administration shall not be granted after the expiration of 21 years from the decedent's death, except on the order of the court, upon cause shown.
When 21 years elapsed
20 Pa.C.S. § 3152, under Dispositions Independent of Letters; Family Exemption; Probate of Wills and Grant of Letters.
20 Pa.C.S. § 3152