Boeing says that 2,000 737s, representing two-thirds of the world's fleet, have passed tests of their rudder-control units. The rudder power control unit (PCU) inspection was ordered by the US Federal Aviation Administration after Boeing engineers concluded that the PCU can jam under extreme conditions. Loss of rudder control is suspected in several unexplained fatal accidents. Operators of the 737 are required to repeat the test every 250h as a safeguard. The US manufacturer is working on an improved in-flight procedure for reacting to a jammed PCU. It is also considering design changes to the PCU.
Source: Flight International
