AD 2005-05-06 Airworthiness Directives; Rolls-Royce plc Models RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 Turbofan Engines

This AD applies to Rolls-Royce plc (RR) models RB211 Trent 768-60, Trent 772-60, and Trent 772B-60 turbofan engines. These engines are installed on, but not limited to, Airbus 330 series airplanes.

You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done. No Revenue Service Surge Margin Testing Allowed (f) Although RR Alert Service Bulletin (ASB) No. RB.211-71-AD509, Revision 3, dated October 17, 2003, allows surge margin testing of engines during revenue service, this AD only allows surge margin testing during dedicated maintenance checks. Initial Surge Margin Testing (g) Perform initial surge margin testing using paragraph 3 and Method A(1) of the Accomplishment Instructions of RR ASB No. RB.211-71-AD509, Revision 3, dated October 17, 2003, as follows: (1) Before further flight, for engines that have accumulated more than 2,000 cycles-since-new (CSN) on the effective date of this AD; and for engines that have accumulated more than 1,000 cycles-since-overhaul (CSO) of the HP compressor casings and blades. (2) Before accumulating 2,000 CSN for engines that have not had an overhaul of the HP compressor casing and blades. (3) Before accumulating 1,000 CSO for engines that have had an overhaul of the HP compressor casings and blades. EEC Software Update (h) Within 6 months from the effective date of this AD, install an EEC that features revised software to increase the in-flight N3 low idle schedule. Information on the revised software standard that features the increase in the in-flight N3 low idle schedule can be found in RR SB No. RB.211-73-AE224. Repetitive Surge Margin Testing (i) For engines that do not have a revised EEC installed, as specified in paragraph (h) of this AD, perform repetitive surge margin testing at intervals not to exceed 130 cycles-since-last surge margin test. Use paragraph 3 and Method A(1) of the Accomplishment Instructions of RR ASB No. RB.211-71-AD509, Revision 3, dated October 17, 2003, for testing. (j) For engines that do have a revised EEC installed, as specified in paragraph (h) of this AD, perform repetitive surge margin testing at intervals not to exceed 160 cycles-since-last surge margin test. Use paragraph 3 and Method A(1) of the Accomplishment Instructions of RR ASB No. RB.211-71-AD509, Revision 3, dated October 17, 2003, for testing. Terminating Action (k) Within 4,500 cycles-in-service after the effective date of this AD, install a stage 1 HP compressor casing and intermediate case outer location ring with wear-resistant coating. Use paragraph 3.A. of the Accomplishment Instructions of RR Service Bulletin No. RB.211-72-D574, Revision 1, dated January 12, 2004, to do this. Performing these actions is considered terminating action for the repetitive surge margin testing required by this AD. Alternative Methods of

This AD results from RR requiring engine electronic controller (EEC) software to be revised, and extending the repetitive interval for surge margin testing for engines that have incorporated the software revision for the EECs. This AD also results from RR introducing a stage 1 high pressure (HP) compressor casing and intermediate case outer location ring with wear-resistant coating, to reduce wear to prevent reduction in surge margin. We are issuing this AD to prevent a possible dual-engine in-flight surge, which could result in dual engine power loss.