AD 2010-12-10 Airworthiness Directives; General Electric Company CF6-45 and CF6-50 Series Turbofan Engines

This AD applies to General Electric Company (GE) CF6-45A, CF6-45A2, CF6-50A, CF6-50C, CF6-50CA, CF6-50C1, CF6-50C2, CF6-50C2B, CF6-50C2D, CF6-50C2-F, CF6-50C2-R, CF6-50E, CF6-50E1, and CF6-50E2 series turbofan engines, with any of the following low-pressure turbine (LPT) rotor stage 3 disks installed:           9061M23P06 9061M23P07 9061M23P08 9061M23P09 9224M75P01 9061M23P10 1473M90P01 1473M90P02 1473M90P03 1473M90P04 9061M23P12 9061M23P14 9061M23P15 9061M23P16 1479M75P01 1479M75P02 1479M75P03 1479M75P04 1479M75P05 1479M75P06 1479M75P07 1479M75P08 1479M75P09 1479M75P11 1479M75P13 1479M75P14 N/A N/A N/A N/A These engines are installed on, but not limited to, Boeing 747-200/-300, DC-10, MD-10, and KC-10 aircraft, and Airbus A300 series aircraft.

You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done. Borescope Inspections of High-Pressure Turbine (HPT) Rotor Stage 1 and Stage 2 Blades (f) Borescope-inspect the HPT rotor stage 1 and stage 2 blades from the forward and aft directions within 10 cycles from the effective date of this AD. You can find further guidance about borescoping in Table 2 of this AD. (g) Thereafter, borescope-inspect the HPT rotor stage 1 and stage 2 blades from the forward and aft directions within every 75 cycles-since-last-inspection (CSLI). You can find further guidance about borescoping in Table 2 of this AD. Additional Borescope Inspections (h) Borescope-inspect the HPT rotor stage 1 and stage 2 blades from the forward and aft directions within the cycle limits after the engine has experienced the events specified in Table 1 of this AD. You can find further guidance about borescoping in Table 2 of this AD. Table 1—Additional Borescope Inspection Criteria If the engine has experienced: Then borescope inspect: (1) An exhaust gas temperature (EGT) above redline Within 10 cycles. (2) A shift in the smoothed EGT trending data that exceeds 18° F (10° C), but is less than or equal to 36° F (20° C) Within 10 cycles. (3) A shift in the smoothed EGT trending data that exceeds 36° F (20° C) Before further flight. (4) A flightcrew reported vibration determined to be caused by the high-pressure rotor (N2) Within 10 cycles from the report. Actions Required for Engines With Damaged HPT Rotor Blades (i) Remove the engine before further flight if the engine fails the borescope inspection in paragraph (f), (g), or (h) of this AD. (j) Before returning the engine to service, fluorescent penetrant inspect the inner diameter surface forward cone body (forward spacer arm) of the LPT rotor stage 3 disk. If a crack is found or if a circumferential band of fluorescence appears, permanently remove the disk from service. EGT System Checks (k) Inspect the turbine midframe (TMF) liner for clocking and subsequent damage to the EGT probes, within 50 cycles from the effective date of this AD or before accumulating 750 CSLI of the TMF liner for clocking, whichever occurs later. You can find further guidance about TMF liner inspections in Table 2 of this AD. (l) Thereafter, inspect the TMF liner for clocking and subsequent damage to the EGT probes within every 750 CSLI. You can find further guidance about TMF liner inspections in Table 2 of this AD. (m) If the engine shows TMF liner clocking resulting in wear through 100% of the wall thickness of the thermocouple guide sleeve, remove the engine and repair the TMF and any damage to the EGT probes before further flight. You can find further guidance about TMF liner inspections in Table 2 of this AD. (n) Check the resistance of the EGT system within 50 cycles from the effective date of this AD or before accumulating 750 cycles-since-the-last-resistance check of the EGT system, whichever occurs later. You can find further guidance about the EGT resistance check in Table 2 of this AD. (o) Thereafter, check the resistance of the EGT system within every 750 CSLI. You can find further guidance about EGT resistance checks in Table 2 of this AD. (p) Repair or replace any EGT system component that fails this check, before further flight. You can find further guidance about the EGT resistance check in Table 2 of this AD. Definitions (q) For the purposes of this AD, an EGT above redline is a confirmed over temperature indication that is not a result of EGT system error. You can find further guidance about troubleshooting EGT above redline in Table 2 of this AD. (r) For the purposes of this AD, a shift in the smoothed EGT trending data is a shift in a rolling average of EGT that can be confirmed by a corresponding shift in the trending of fuel flow or fan speed/core speed relationship. You can find further guidance about evaluating EGT trend data in GE Company Service Rep Tip 373 “Guidelines For Parameter Trend Monitoring.” Table 2—AMM References for Further Guidance Engine inspections Boeing 747/CF6-50/-45 AMM ATA Boeing DC-10/CF6-50 AMM ATA Boeing MD-10/CF6-50 AMM ATA Airbus A300/CF6-50 AMM ATA Borescope Inspection of HPT Rotor Stage 1 and Stage 2 Blades 72-00-00, 601 72-53-00 72-53-00 72-53-00. Exceeded EGT Limit 72-00-00, 601 72-00-00, 601 72-00-00, 6-1 72-00-00, 601. EGT Resistance Check 77-21-00, 501 77-21-00 77-21-01 77-21-00. TMF Liner Clocking 72-00-00, 601, and 72-52-00 72-54-00 72-54-00 and 77-21-01 72-54-00. Previous Credit (s) A borescope inspection performed before the effective date of this AD using AD 2010-06-15 and within the last 75 cycles, satisfies the initial borescope inspection requirement in paragraph (f) of this AD. Alternative Methods of

This AD results from reports received of two additional LPT rotor stage 3 disk events. We are issuing this AD to prevent critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane.