Airworthiness Directive · Amendment 39-11760 · General Electric Company CF6-45/50 Series Turbofan Engines
General Electric Company CF6-45/50 Series Turbofan Engines
General Electric Company (GE) Model CF6-45/50 series turbofan engines, installed on but not limited to Airbus Industrie A300 series, Boeing Company 747 series, and McDonnell Douglas Corporation DC-10 series airplanes
Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (j) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment adopts a new airworthiness directive (AD) that is applicable to General Electric Company CF6-45/50 series turbofan engines. This AD requires initial and repetitive inspections for cracks in the stage 14 high pressure compressor (HPC) disk lock slots, and removal from service of certain disks, at the first piece-part level or HPC rotor disassembly level exposure, after 6,000 cycles since new (CSN). This amendment is prompted by reports of stage 14 HPC disk lock slot cracks discovered during shop fluorescent penetrant inspections. The actions specified by this AD are intended to prevent stage 14 HPC disk failure, which could result in an uncontained engine failure and damage to the aircraft.
To prevent a stage 14 high pressure compressor (HPC) disk failure, which could result in uncontained engine failure and damage to the aircraft, accomplish the following:
(a) Perform initial inspections of HPC stage 14 disks, part numbers (P/N's) 9080M34P03, 9080M34P04, 9080M34P05 and 9349M91P04, with serial number (SN) prefixes GWN, MPO, RRY, and SNL, and disk SN's SNE00001 through SNE00017, and disk SN's SNE01101 through SNE01110, in accordance with paragraphs 2.A. through 2.B. of GE CF6-50 ASB No. 72-A1144, dated March 19, 1998, or ASB No. 72-A1144, Revision 1, dated May 13, 1999, and the following schedule:
(1) Inspect disks with 6,500 cycles since new (CSN) or less on the effective date of this AD before accumulating 9,800 CSN.
(2) Inspect disks with more than 6,500 CSN on the effective date of this AD no later than the next engine shop visit (ESV) after the effective date of this AD or before accumulating an additional 3,300 cycles-in-service (CIS) after the effective date of this AD, whichever occurs first.
(b) Perform repetitive inspections of HPC stage 14 disks, P/N's 9080M34P03, 9080M34P04, 9080M34P05 and 9349M91P04, with SN prefixes GWN, MPO, RRY, and SNL, and disk SN's SNE00001 through SNE00017, and disk SN's SNE01101 through SNE01110, in accordance with paragraphs 2.A. through 2.B. of GE CF6-50 ASB No. 72-A1144, dated March 19, 1998, or ASB No. 72-A1144, Revision 1, dated May 13, 1999, and the following schedule:
(1) For disks with less than 9,800 CSN at the time of the last inspection, perform repetitive inspections no later than 9,800 CSN or before accumulating 3,300 cycles since last inspection (CSLI), whichever occurs later.
(2) For disks with 9,800 CSN or greater at the time of the last inspection, perform repetitive inspections no later than 3,300 CSLI.
(c) Perform initial inspections of HPC stage 14 disks, P/N's 9080M34P03, 9080M34P04, 9080M34P05 and 9349M91P04 with SN prefixes SNG and SNE, except disk SN's SNE00001 through SNE00017 and SNE01101 through SNE01110, in accordance with paragraphs 2.A. through 2.B. of GE CF6-50 ASB No. 72-A1144, dated March 19, 1998, or ASB No. 72-A1144, Revision 1, dated May 13, 1999, and the following schedule:
(1) Inspect disks with 4,200 CSN or less on the effective date of this AD before accumulating 7,500 CSN.
(2) Inspect disks with more than 4,200 CSN but less than 9,000 CSN on the effective date of this AD at the next ESV after the effective date of this AD, before accumulating an additional 3,300 CIS after the effective date of this AD, or before accumulating 11,000 CSN, whichever occurs first.
(3) Inspect disks with 9,000 CSN or greater on the effective date of this AD, at the next ESV after the effective date of this AD, or before accumulating an additional 2,000 CIS after the effective date of this AD, whichever occurs first.
(d) Perform repetitive inspections of HPC stage 14 disks, P/N's 9080M34P03, 9080M34P04, 9080M34P05 and 9349M91P04 with SN prefixes SNG and SNE, except disk SN's SNE00001 through SNE00017 and SNE01101 through SNE01110, in accordance with paragraphs 2.A. through 2.B. of GE CF6-50 ASB No. 72-A1144, dated March 19, 1998, or ASB No. 72-A1144, Revision 1, dated May 13, 1999, and the following schedule:
(1) For disks with less than 7,500 CSN at the time of the last inspection, perform repetitive inspections no later than 7,500 CSN or before accumulating 3,300 CSLI, whichever occurs later.
(2) For disks with 7,500 CSN or greater at the time of the last inspection, perform repetitive inspections no later than 3300 CSLI.
(e) Remove from service prior to further flight stage 14 HPC disks that equal or exceed the reject criteria established by GE CF6-50 ASB 72-A1144, dated March 19, 1998, or ASB No. 72-A1144, Revision 1, dated May 13, 1999.
(f) Remove from service, HPC stage 14 disks, P/N's 9080M34P03, 9080M34P04, 9080M34P05 and 9349M91P04 with SN prefixes SNG and SNE, except disk SN's SNE00001 through SNE00017 and SNE01101 through SNE01110, with greater than 6,000 CSN after the effective date of this AD, at the next piece-part level exposure or at the next HPC rotor disassembly level exposure after the effective date of this AD.
(g) Replacement of the stage 14 HPC disk, P/N's 9080M34P03, 9080M34P04, 9080M34P05, 9349M91P04, with a stage 11-14 spool shaft is terminating action for the inspection requirements of this AD.
(h) Report the results of inspections that equal or exceed the reject criteria within five days of the inspection to: Manager, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299, telephone, (781) 238-7141, fax, (781) 238-7199. The following information must be included in the report:
(1) HPC Stage 14 rotor disk P/N,
(2) HPC Stage 14 rotor disk SN,
(3) HPC Stage 14 rotor disk CSN,
(4) HPC Stage 14 rotor disk CSLI, and
(5) Date and location of inspection.
Reporting requirements have been approved by the Office of Management and Budget (OMB) and assigned OMB control number 2120-0056.
(i) For the purpose of this AD, the following definitions apply:
(1) HPC Rotor disassembly occurs if any of the HPC Rotor bolted flange joints are separated, such as the Stage 2 joint to accomplish the Stage 3-9 Spool inspection.
(2) Piece-part exposure is defined as disassembly and removal of the stage 14 disk from the HPC rotor structure, regardless of any blades, locking lugs, bolts or balance weights assembled to the disk.
(3) An engine shop visit is defined as the introduction of an engine into a shop when a major engine flange is separated. The following maintenance actions are not considered engine shop visits for the purpose of this AD:
(i) Introduction of an engine into a shop solely for removal or replacement of the Stage 1 Fan Disk;
(ii) Introduction of an engine into a shop solely for replacement of the Turbine Rear Frame;
(iii) Introduction of an engine into a shop solely for replacement of the Accessory Gearbox or Transfer Gearboxes;
(iv) Introduction of an engine into a shop solely for replacement of the Fan Forward Case.
(v) Introduction of an engine into a shop for any combination of exceptions specified in paragraphs (i)(3)(i) through (i)(3)(iv);
