COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Rolls Royce Turbine Engines - RB211 Series AD/RB211/1 Amdt 4 A.V.M. Indication and Oil Pressure Indication and M.E.L.Requirements, Procedures 4/94 Applicability: RB211-524D4-19 series engines. Requirement: Part 1. For aircraft that have been modified to incorporate Rolls Royce SB RB211-72-7836 and Vibro Meter SB RB211-77-002 fitted on Boeing 747 aircraft, action in accordance with Rolls Royce SB RB211-77-A9663. Note: UK CAA AD No. 015-10-93 refers. Part 2. For aircraft not modified as in part 1, action in accordance with Rolls Royce SB RB211-77-A8446. Note: UK CAA AD No. 005-05-88 refers. Compliance: With effect from 18 April 1994. Background: Part 1. SB RB211-77-A9663 outlines updated conditional alternative operating procedures in the event of an Airborne Vibration Monitoring (AVM) system warning. The modifications introduced by SB RB211-72-7836 have proven to be successful in slowing the rate of failure progression following the failure of the location bearings. As such, there is now time to interrogate the AVM system to confirm if the warning is genuine. This will in turn reduce the number of unnecessary engine shut-downs. Part 2. For aircraft that have not incorporated SB RB211-72-7836, the operating procedures covered by Rolls Royce SB RB211-77-A8446 are still mandatory.