AD 2016-20-01 Amendment 39-18667

We are adopting a new airworthiness directive (AD) for Bell Model 427 and Model 429 helicopters. This AD requires replacing certain engine and transmission oil check valves. This AD also prohibits installing the affected check valves on any helicopter. This AD is prompted by a report of several cracked or leaking check valves. These actions are intended to detect and prevent a cracked or leaking check valve which could result in loss of lubrication to the engine or transmission, failure of the engine or transmission, and subsequent loss of control of the helicopter.