AD 2006-08-10 Airworthiness Directives; General Electric Company CT64-820-4 Turboprop Engines

This AD applies to General Electric Company (GE) CT64-820-4 turboprop engines that use any of the rotating parts listed in Table 1 of this AD. These engines are installed on, but not limited to, DeHavilland DHC-5D Buffalo airplanes. Table 1.—Affected Rotating Parts Rotor assembly Part nomenclature Part No. Compressor Shaft, Front 5007T03P03   Disk, Stage 1 5015T92P01   Retainer, Disk, Stage 1 5013T71P01   Disk, Stage 2 5015T93P01   Spacer, Disk, Stage 2 5015T94P01   Disk, Stage 3 5015T95P01   Spool, Rotor, Front 6003T84P02   Spool, Rotor, Rear 6005T18P01   Shaft, Rear 6005T26P01 Gas Generator Turbine Disk and Shaft, Stage 1 6014T70P02   Disk, Stage 2 4007T83P02   Ring, Torque 3008T60P02   Seal, Air, Stage 1 4007T94G02   Plate, Cooling 3008T52P02   Plate, Cooling 4022T37P01   Seal, Interstage 5006T54P02   Seal, Air, Rear 4022T36P01   Seal, Air, Rear 4022T36P03 Power Turbine Disk, Stage 3 4008T65P02   Disk, Stage 4 5006T16P03   Disk, Stage 4 5006T16P04   Seal, Interstage 4008T29P01   Shaft, Main 5009T73P02   Shaft, Main 6012T83P02   Tiebolt, Power Turbine Rotor 3008T44P02

You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done. (h) If performing the actions required by this AD for “Data Fleet” engines, follow paragraphs (j) through (o). (i) If performing the actions required by this AD for “No-Data Fleet” engines, follow paragraphs (p) through (u). Data Fleet Rotating Part Removal Requirements (j) For parts listed in Table 3 of this AD and installed in serviceable engines (those that are in service or have met the requirements for and have been approved for return to service) on the effective date of this AD, do the following: (1) If the cycles-since-new (CSN) of a part listed in Table 3 of this AD are equal to or more than Table 3, Limit 2 as of the effective date of this AD, remove the part before exceeding 900 additional cycles-in-service (CIS) or Table 3, Limit 1, whichever occurs first, but not later than July 31, 2013. (2) If the CSN for a part listed in Table 3 of this AD are fewer than Table 3, Limit 2 as of the effective date of this AD, remove the part from service before exceeding Table 3, Limit 3, but not later than July 31, 2013. Table 3.—Affected Data Fleet Rotating Part Removal Requirements Rotor Nomenclature Part No. Limit 1 (cycles) Limit 2 (cycles) Limit 3 (cycles) Compressor Shaft, Front 5007T03P03 30,000 29,100 30,000   Disk, Stage 1 5015T92P01 13,000 8,100 9,000   Retainer, Disk, Stage 1 5013T71P01 30,000 29,100 30,000   Disk, Stage 2 5015T93P01 23,000 8,100 9,000   Spacer, Disk, Stage 2 5015T94P01 30,000 8,100 9,000   Disk, Stage 3 5015T95P01 9,000 8,100 9,000   Spool, Rotor, Front 6003T84P02 5,100 2,100 3,000   Spool, Rotor, Rear 6005T18P01 19,000 3,500 4,400   Shaft, Rear 6005T26P01 30,000 8,100 9,000 Gas Generator Turbine Disk and Shaft, Stage 1 6014T70P02 7,000 6100 7000   Disk, Stage 2 4007T83P02 11,300 5,400 6,300   Ring, Torque 3008T60P02 30,000 6,100 7,000   Seal, Air, Stage 1 4007T94G02 30,000 11,700 12,600   Plate, Cooling 3008T52P02 5,000 4,100 5,000   Plate, Cooling 4022T37P01 5,000 4,100 5,000   Seal, Interstage 5006T54P02 5,100 4,200 5,100   Seal, Air, Rear 4022T36P01 5,000 4,100 5,000   Seal, Air, Rear 4022T36P03 5,000 4,100 5,000 Power Turbine Disk, Stage 3 4008T65P02 30,000 12,100 13,000   Disk, Stage 4 5006T16P03 30,000 12,100 13,000   Disk, Stage 4 5006T16P04 30,000 12,100 13,000   Seal, Interstage 4008T29P01 30,000 12,100 13,000   Shaft, Main 5009T73P02 13,000 12,100 13,000   Shaft, Main 6012T83P02 13,000 12,100 13,000   Tiebolt, Power Turbine Rotor 3008T44P02 13,000 12,100 13,000 (k) For all rotating parts listed in Table 3 of this AD and put into service after the effective date of this AD, remove from service before the CSN exceeds Table 3, Limit 3, but not later than July 31, 2013. (l) After the effective date of this AD: (1) Do not install any part listed in Table 3 of this AD that has a CSN equal to or more than Table 3, Limit 3. (2) If the CSN for a part listed in Table 3 of this AD are fewer than Table 3, Limit 3: (i) Until July 31, 2007, you may return the part to service, if the part passes the applicable inspections specified in the CT64-820-4 Engine Overhaul Manual, SEI-448. (ii) You must remove the part from service before Table 3, Limit 3 is exceeded, but no later than July 31, 2013. (iii) After July 31, 2007, do not install any part listed in Table 3 of this AD. (m) On July 31, 2007, for engines in service that have a part listed in Table 3 of this AD, remove the affected part before exceeding Table 3, Limit 3, but no later than July 31, 2013. (n) For main shafts, P/N 5009T73P02, and P/N 6012T83P02, and power turbine rotor tiebolt, P/N 3008T44P02, with unknown CSN do the following: (1) Assign each part a CSN value of 7,400 CSN as of the effective date of this AD and refer to Table 3 of this AD for removal requirements. (2) Continue to track the parts starting from 7,400 CSN and remove from service as specified in paragraphs (j) through (n) of this AD, but no later than July 31, 2013. (o) For rear air seal, P/N 4022T36P03, and power turbine stage 4 disk, P/N 5006T16P04, with unknown CSN, remove the part before exceeding 10 additional cycles, but no later than July 31, 2013. No-Data Fleet Rotating Part Removal Requirements (p) For parts listed in Table 4 of this AD and installed in serviceable engines (those that are in service, or have met the requirements for and have been approved for return to service) on the effective date of this AD, do the following: (1) If the CSN of a part listed in Table 4 of this AD are equal to or more than Table 4, Limit 2 as of the effective date of this AD, remove the part before exceeding 50 additional CIS or Table 4, Limit 1, whichever occurs first, but not later than July 31, 2013. (2) If the CSN for a part listed in Table 4 of this AD are fewer than Table 4, Limit 2 as of the effective date of this AD, remove the part from service before exceeding Table 4, Limit 3, but not later than July 31, 2013. (q) For all rotating parts listed in Table 4 of this AD and put into service after the effective date of this AD, remove from service before the CSN exceeds Table 4, Limit 3, but not later than July 31, 2013. Table 4.—Affected No-Data Fleet Rotating Part Removal Requirements Rotor Nomenclature Part No. Limit 1 (cycles) Limit 2 (cycles) Limit 3 (cycles) Compressor Shaft, Front 5007T03P03 30,000 29,950 30,000   Disk, Stage 1 5015T92P01 13,000 8,950 9,000   Retainer, Disk, Stage 1 5013T71P01 30,000 29,950 30,000   Disk, Stage 2 5015T93P01 23,000 8,950 9,000   Spacer, Disk, Stage 2 5015T94P01 30,000 8,950 9,000   Disk, Stage 3 5015T95P01 9,000 8,950 9,000   Spool, Rotor, Front 6003T84P02 5,100 2,950 3,000   Spool, Rotor, Rear 6005T18P01 19,000 4,350 4,400   Shaft, Rear 6005T26P01 30,000 8,950 9,000 Gas Generator Turbine Disk and Shaft, Stage 1 6014T70P02 7,000 6,950 7,000   Disk, Stage 2 4007T83P02 11,300 6,250 6,300   Ring, Torque 3008T60P02 30,000 6,950 7,000   Seal, Air, Stage 1 4007T94G02 30,000 12,550 12,600   Plate, Cooling 3008T52P02 5,000 4,950 5,000   Plate, Cooling 4022T37P01 5,000 4,950 5,000   Seal, Interstage 5006T54P02 5,100 5,050 5,100   Seal, Air, Rear 4022T36P01 5,000 4,950 5,000   Seal, Air, Rear 4022T36P03 5,000 4,950 5,000 Power Turbine Disk, Stage 3 4008T65P02 30,000 12,950 13,000   Disk, Stage 4 5006T16P03 30,000 12,950 13,000   Disk, Stage 4 5006T16P04 30,000 12,950 13,000   Seal, Interstage 4008T29P01 30,000 12,950 13,000   Shaft, Main 5009T73P02 13,000 12,950 13,000   Shaft, Main 6012T83P02 13,000 12,950 13,000   Tiebolt, Power Turbine Rotor 3008T44P02 13,000 12,950 13,000 (r) After the effective date of this AD: (1) Do not install any part listed in Table 4 of this AD that has a CSN equal to or more than Table 4, Limit 3. (2) If the CSN for a part listed in Table 4 of this AD are fewer than Table 4, Limit 3: (i) Until July 31, 2007, you may return the part to service, if the part passes the applicable inspections specified in the CT64-820-4 Engine Overhaul Manual, SEI-448. (ii) You must remove the part from service before Table 4, Limit 3 is exceeded, but no later than July 31, 2013. (iii) After July 31, 2007, do not install any part listed in Table 4 of this AD. (s) On July 31, 2007, for engines in service that have a part listed in Table 4 of this AD, remove the affected part before exceeding Table 4, Limit 3, but no later than July 31, 2013. (t) For main shafts P/N 5009T73P02, and P/N 6012T83P02, and power turbine rotor tiebolt, PN 3008T44P02, with unknown CSN, remove the part before exceeding 50 additional cycles (u) For rear air seal, P/N 4022T36P03, and power turbine stage 4 disk, P/N 5006T16P04, with unknown CSN, remove the part before exceeding 10 additional cycles, but no later than July 31, 2013. Log Book Entry (v) For all engines, calculate the cycles remaining on the affected rotating parts and make an entry in the Engine Log Book marked with the engine S/N and its fleet category, either “DATA FLEET” or “NO-DATA FLEET.” (1) Date and file the record in the Engine Log Book. (2) Note in the Engine Log Book that AD 2006-08-10 has been complied with. Alternative Methods of

This AD results from the manufacturer's discovery of cracks in some rotating parts. We are issuing this AD to prevent cracks in the rotating parts that could cause compressor and turbine wheel fracture and uncontained engine failure. An uncontained engine failure could cause possible damage to the airplane. Definition of “Data Fleet” and “No-Data” Fleet Engines (e) For the purposes of this AD, “Data Fleet” is defined as a category of engines for which the engine serial numbers (SNs) are listed in Table 2 of this AD, and the following information has been provided to the manufacturer and included in the data analysis: (1) Current configuration of all life-limited parts. (2) Current cycles of life-limited parts. (3) Engine utilization rate (hours/month). Table 2.—Engine SNs in the Data Fleet           268504 268565 268605 268646 268662 268505 268569 268606 268647 268666 268509 268573 268608 268648 268667 268511 268574 268620 268649 268669 268514 268575 268622 268650 268670 268529 268580 268636 268653 268672 268534 268583 268637 268655 268674 268535 268588 268638 268656 268679 268537 268589 268641 268658 268686 268545 268590 268642 268659 268689 268549 268596 268643 268660 268690 268562 268603 268644 268661 268691 (f) For the purposes of this AD, “No-Data Fleet” is defined as a category of engines for which the engine SNs are not listed in Table 2 of this AD. The operators of the “No Data Fleet” engines did not supply the data listed in paragraph (e) to the manufacturer.