Airworthiness Directive · Amendment 39-16331 · General Electric Company CF6-45 and CF6-50 Series Turbofan Engines
General Electric Company CF6-45 and CF6-50 Series Turbofan Engines
Superseded. A later AD replaced this one: AD 2011-02-07. Comply with the one in force.
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.
The FAA is superseding an existing airworthiness directive (AD) for General Electric Company (GE) CF6-45 and CF6-50 series turbofan engines with certain low-pressure turbine (LPT) rotor stage 3 disks installed. That AD required initial and repetitive borescope inspections of the high-pressure turbine (HPT) rotor stage 1 and stage 2 blades for wear and damage, including excessive airfoil material loss. That AD also required fluorescent penetrant inspection (FPI) of the LPT rotor stage 3 disk under certain conditions and removal of the disk from service before further flight if found cracked. This ad requires the same inspections at reduced intervals and additional borescope inspections. This AD also requires repetitive exhaust gas temperature (EGT) system checks. 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.
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-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.
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.
| 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. |
(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.
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.
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.”
| 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. |
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.
