Airworthiness Directive · Amendment 39-16580 · 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Superseded.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 2012-02-07. Comply with the one in force.
This AD applies to the following engines with any of the low-pressure turbine (LPT) rotor stage 3 disk part numbers listed in Table 1 of this AD installed in:
(1) General Electric Company (GE) CF6-45A, CF6-45A2, CF6-50A, CF6-50C, CF6-50CA, CF6-50C1, CF6-50C2, CF6-50C2B, CF6-50C2D, CF6-50E, CF6-50E1, and CF6-50E2 turbofan engines, including engines marked on the engine data plate as CF6-50C2-F and CF6-50C2-R.
(2) These engines are installed on, but not limited to, Airbus A300 series, Boeing 747 series, McDonnell Douglas DC-10 series, and DC-10-30F (KDC-10) airplanes.
| 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 |
We are 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 currently requires 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 requires 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. That AD also requires repetitive exhaust gas temperature (EGT) system checks (inspections). This AD requires HPT rotor stage 1 and stage 2 blade inspections and EGT system inspections. This AD also requires FPI of the LPT rotor stage 3 disk under certain conditions, removal of the disk from service before further flight if found cracked, and an ultrasonic inspection (UI) of the LPT rotor stage 3 disk forward spacer arm. This AD also requires initial and repetitive engine core vibration surveys and reporting to the FAA any crack findings, disks that fail the UI, and engines that fail the engine core vibration survey. This AD was prompted by reports received of additional causes of HPT rotor imbalance not addressed in AD 2010-12-10, and 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.
Comply with this AD within the compliance times specified, unless already done.
For the borescope inspections required by paragraphs (f)(1), (f)(2), and (f)(3) of this AD, inspect the blades from the forward and aft directions. Inspect all areas of the blade airfoil: Your inspection must include blade leading and trailing edges, and their convex and concave airfoil surfaces. Inspect for signs of impact, cracking, burning, damage, or distress.
(1) Perform an initial borescope inspection of the HPT rotor stage 1 and stage 2 blades, within 10 cycles after the effective date of this AD.
(2) Thereafter, repeat the borescope inspection of the HPT rotor stage 1 and stage 2 blades within every 75 cycles-since-last-inspection (CSLI).
(3) Borescope-inspect the HPT rotor stage 1 and stage 2 blades within the cycle limits after the engine has experienced any of the events specified in Table 2 of this AD.
(4) Remove any engine from service before further flight if the engine fails any of the borescope inspections required by this AD.
| If the engine has experienced: | Then Borescope-Inspect: |
|---|---|
| (i) An exhaust gas temperature (EGT) above redline | Within 10 cycles. |
| (ii) 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. |
| (iii) A shift in the smoothed EGT trending data that exceeds 36 °F (20 °C) | Before further flight. |
| (iv) Two consecutive raw EGT trend data points that exceed 18 °F (10 °C) above the smoothed average, but is less than or equal to 36 °F (20 °C) | Within 10 cycles. |
| (v) Two consecutive raw EGT trend data points that exceed 36 °F (20 °C) above the smoothed average | Before further flight. |
For those engines that fail any borescope inspection requirements of this AD, 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, remove the disk from service.
Inspect the EGT thermocouple probe for damage within 50 cycles after the effective date of this AD or before accumulating 750 CSLI, whichever occurs later.
(i) Thereafter, re-inspect the EGT thermocouple probe for damage within every 750 CSLI.
(j) If any EGT thermocouple probe shows wear through the thermocouple guide sleeve, remove and replace the EGT thermocouple probe before further flight, and ensure the turbine mid-frame liner does not contact the EGT thermocouple probe.
Perform an EGT system resistance check within 50 cycles from the effective date of this AD or before accumulating 750 cycles-since-the-last-resistance check on the EGT system, whichever occurs later.
(l) Thereafter, repeat the EGT system resistance check within every 750 cycles-since-the-last-resistance check.
(m) Remove and replace, or repair any EGT system component that fails the resistance system check before further flight.
Within 75 cycles after the effective date of this AD, perform a UI of the forward cone body (forward spacer arm) of the LPT rotor stage 3 disk. Use paragraphs E. through K. of Appendix A of GE Service Bulletin (SB) No. CF6-50-SB 72-1312, Revision 1, dated October 18, 2010, to do the UI.
Within 75 cycles after the effective date of this AD, perform an initial engine core vibration survey.
(1) Use approximately a one-minute acceleration and a one-minute deceleration of the engine between ground idle and 84% N2 (about 8,250 rpm) to perform the engine core vibration survey.
(2) Use a spectral/trim balance analyzer or equivalent, to determine the N2 rotor vibration.
(p) Thereafter, within every 350 cycles-since-the-last-engine core vibration survey, perform the engine core vibration survey as required in paragraphs (o)(1) through (o)(2) of this AD.
(q) If the vibration level is above 5 mils Double Amplitude then before further flight, remove the engine from service.
(r) For those engines that fail any engine core vibration survey requirements of this AD, 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, remove the disk from service.
(s) If the engine has experienced any vibration reported by maintenance or flight crew that is suspected to be caused by the HPT rotor (N2), perform the engine core vibration survey as required in paragraphs (o)(1) through (o)(2) of this AD within 10 cycles after the report.
(t) You can find further guidance about performing the engine core vibration survey in GE SB No. CF6-50-SB 72-1313, Revision 1, dated October 18, 2010.
Report to the FAA within 10 days after any of the following:
(1) Any crack findings; and
(2) Any disks that failed a UI performed as specified in paragraph (n) of this AD; and
(3) Any engines that failed an engine core vibration survey as specified in paragraphs (o) and (p) of this AD.
(4) Submit these findings to FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e- mail: tomasz.rakowski@faa.gov; phone: 781-238-7735; fax: 781-238-7199.
(5) A federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a current valid OMB Control Number. The OMB Control Number for this information collection is 2120-0056. Public reporting for this collection of information is estimated to be approximately 5 minutes per response, including the time for reviewing instructions, completing and reviewing the collection of information. All responses to this collection of information are mandatory. Comments concerning the accuracy of this burden and suggestions for reducing the burden should be directed to the FAA at: 800 Independence Ave., SW., Washington, DC 20591, Attn: Information Collection Clearance Officer, AES-200.
(v) 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.
(w) 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 (N1/N2) relationship. You can find further guidance about evaluating EGT trend data in GE Company Service Rep Tip 373 “Guidelines For Parameter Trend Monitoring.”
(x) A borescope inspection performed before the effective date of this AD using AD 2010-06-15, Amendment 39-16240 (75 FR 12661, March 17, 2010) or AD 2010-12-10, Amendment 39-16331 (75 FR 32649, June 9, 2010) within the last 75 cycles, satisfies the initial borescope inspection requirement in paragraph (f)(1) of this AD.
(y) A UI performed before the effective date of this AD using GE SB No. CF6-50-SB 72-1312, dated August 9, 2010 or GE SB No. CF6-50-SB 72-1312 Revision 1, dated October 18, 2010, satisfies the inspection requirement in paragraph (n) of this AD.
(z) An engine core vibration survey performed before the effective date of this AD using GE SB No. CF6-50-SB 72-1313, dated August 9, 2010 or GE SB No. CF6-50-SB 72-1313 Revision 1, dated October 18, 2010, within the last 350 cycles, satisfies the initial survey requirement in paragraph (o) of this AD.
