The Army said it has inspected its fleet of CH-47D Chinook helicopters without finding any faulty transmissions and returned them to flight status. It grounded its 234 medium-lift Chinooks on Dec. 23, 1988, in what it termed a precautionary move after the manufacturer, the Boeing Co., reported that “certain transmissions may have been improperly assembled.” Inspections of the aircraft did not uncover any such problem, Army spokeswoman Paige Eversole said. She said the inspections were considered complete even though 15 Chinooks had yet to be checked. The 15 include 10 used to train mechanics and five undergoing maintenance, she said. Ten Chinooks have been involved in accidents since 1985.