Airworthiness Directive · Amendment 39-19186 · Turbine engine reduction gear
General Electric Company Turboprop Engines
Superseded. A later AD replaced this one: AD 2023-21-07. Comply with the one in force.
This AD applies to General Electric Company (GE) CT7-5A2, CT7-5A3, CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C and CT7-9C3 model turboprop engines with main propeller shaft, part number 77581-11, installed.
We are adopting a new airworthiness directive (AD) for certain General Electric Company (GE) CT7-5A2, CT7-5A3, CT7-7A, CT7-7A1, CT7- 9B, CT7-9B1, CT7-9B2, CT7-9C and CT7-9C3 model turboprop engines. This AD requires initial and repetitive visual inspection and fluorescent- penetrant inspection (FPI) of the main propeller shaft. This AD was prompted by the failure of a main propeller shaft. We are issuing this AD to address the unsafe condition on these products.
(1) For propeller gear boxes (PGBs) with 46,000 hours time since new (TSN) or more, perform cleaning, visual inspection, and fluorescent-penetrant inspection (FPI) within 150 hours time in service (TIS) after the effective date of this AD, or one month after the effective date of this AD, whichever occurs first.
(2) For PGBs with 40,000 hours TSN or more, but less than 46,000 hours TSN, perform cleaning, visual inspection, and FPI within 500 hours TIS after the effective date of this AD, not to exceed 46,150 TSN or four months after the effective date of this AD, whichever occurs first.
(3) For PGBs with 30,000 hours TSN or more, but less than 40,000 hours TSN, perform cleaning, visual inspection, and FPI within 1,000 hours TIS after the effective date of this AD, not to exceed 40,500 TSN or eight months after the effective date of this AD, whichever occurs first.
(4) For PGBs with less than 30,000 hours TSN, perform cleaning, visual inspection, and FPI at the next propeller removal, not to exceed 31,000 hours TSN.
(5) Perform the cleaning, visual inspection and FPI, as follows:
(i) Clean the main propeller shaft flange. Use the instructions in paragraph 5, “Main Propeller Shaft,” in MM 72-10-00, PROPELLER GEARBOX—CLEANING from GE CT7B Maintenance Manual SEI-576, Rev. 60, dated October 1, 2017.
(ii) Visually inspect the main propeller shaft for wear, corrosion, and cracking. Use the instructions in paragraph 5.A., “Main Propeller Shaft,” in MM 72-10-00, PROPELLER GEARBOX—INSPECTION from GE CT7B Maintenance Manual SEI-576, Rev. 60, dated October 1, 2017.
(iii) Spot-fluorescent-penetrant inspect the area on the main propeller shaft flange face within 0.5 inches radially adjacent to the dowel pin holes for cracks. Use the instructions in SPM 70-32-03, SPOT-FLUORESCENT PENETRANT—INSPECTION, Task 70-32-03-230-002 from GE GEK 9250, Commercial Engine Standard Practices Manual, Rev. 106, dated April 1, 2007.
(6) Repeat the cleaning, visual inspection, and FPI of the main propeller shaft at each removal of the propeller.
(7) Before further flight, remove from service any main propeller shaft found cracked, or with corrosion or wear beyond the limits specified in SPM 70-32-03, SPOT-FLUORESCENT PENETRANT—INSPECTION, Task 70-32-03-230-002, from GE GEK 9250, Commercial Engine Standard Practices Manual, Rev. 106, dated April 1, 2007.
