Airworthiness Directive · Amendment 39-22579 · Turbine engine reduction gear
General Electric Company Engines
This AD applies to General Electric Company (GE) Model CT7-5A2, CT7-5A3, CT7-7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and CT7-9C3 engines.
The FAA is superseding Airworthiness Directive (AD) 2018-03-13 for certain General Electric Company (GE) Model CT7-5A2, CT7-5A3, CT7- 7A, CT7-7A1, CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and CT7-9C3 engines. AD 2018-03-13 required initial and repetitive visual inspections and fluorescent penetrant inspections (FPIs) of the main propeller shaft. This AD was prompted by an in-flight failure of a main propeller shaft on a GE Model CT7-9B engine, resulting in the loss of the propeller. This AD requires initial and repetitive visual inspections, FPIs, and ultrasonic inspections (USIs) of the main propeller shaft. Depending on the results of these inspections, this AD requires replacement of the main propeller shaft. As an optional terminating action to these inspections, this AD requires revising the airworthiness limitations section (ALS) of the existing maintenance manual (MM) and the operator's existing approved maintenance program or inspection program, as applicable, to incorporate incorporating the tasks and reduced inspection thresholds for the main propeller shaft. The FAA is issuing this AD to address the unsafe condition on these products.
(1) For affected CT7-5A2, CT7-5A3, CT7-9B, CT7-9B1, and CT7-9B2 model engines, using the compliance times specified in Figure 1 to paragraph (g)(1) of this AD, perform initial and repetitive visual inspections, fluorescent penetrant inspections (FPIs), and ultrasonic inspections (USIs) of the main propeller shaft.
(2) For affected CT7-7A, CT7-7A1, CT7-9C, and CT7-9C3 model engines, using the compliance times specified in Figure 2 to paragraph (g)(2) of this AD, perform initial and repetitive visual inspections, FPIs, and USIs of the main propeller shaft.
(3) Perform the visual inspections, FPIs, and USIs required by paragraphs (g)(1) and (2) of this AD as follows:
(i) Prior to performance of the inspections, clean the main propeller shaft flange using the Accomplishment Instructions, paragraph 3.B., of GE Service Bulletin (SB) CT7-TP 72-0541 R01, dated November 18, 2021 (GE SB CT7-TP 72-0541).
(ii) Visually inspect the main propeller shaft for wear, corrosion, and cracking using the Accomplishment Instructions, paragraph 3.C.(1), of GE SB CT7-TP 72-0541.
(iii) Spot-FPI the area on the main propeller shaft flange face using the Accomplishment Instructions, paragraph 3.C.(2)(a), of GE SB CT7-TP 72-0541.
(iv) USI the two dowel pin holes of the main propeller shaft using the Accomplishment Instructions, paragraph 3.C.(3)(a), of GE SB CT7-TP 72-0541.
(4) If a crack or rejectable indication is found during the initial and repetitive visual inspections, FPIs, or USIs required by paragraphs (g)(1) through (3) of this AD, before further flight, remove the main propeller shaft from service and replace it with a part eligible for installation.
(5) For all affected engines, if the main propeller shaft CSN is unknown, use the propeller gearbox (PGB) CSN. If the PGB CSN is unknown, assume the inspection threshold is exceeded.
Accomplishing the actions in paragraphs (h)(1) through (4) of this AD, as applicable by engine model, constitutes terminating action for the inspections required by paragraphs (g)(1) through (3) of this AD.
(1) For affected CT7-5A2, CT7-5A3, CT7-7A, and CT7-7A1 model engines, revise the airworthiness limitations section (ALS) of the existing maintenance manual (MM) and the operator's existing approved maintenance program or inspection program, as applicable, by incorporating the information in Figure 3 to paragraph (h)(1) of this AD.
(2) For affected CT7-9B, CT7-9B1, CT7-9B2, CT7-9C, and CT7-9C3 model engines, revise the ALS of the existing MM and the operator's existing approved maintenance program or inspection program, as applicable, by incorporating the information in Figure 4 to paragraph (h)(2) of this AD.
(3) Thereafter, except as provided in paragraph (k) of this AD, no alternative inspection times or intervals may be approved for this main propeller shaft.
(4) The optional terminating actions in paragraphs (h)(1) and (2) of this AD may be performed by the owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with this AD in accordance with 14 CFR 43.9(a) and 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417, 121.380, or 135.439.
For the purpose of this AD, a “part eligible for installation” is a main propeller shaft that has been inspected in accordance with paragraphs (g)(1) or (2), and (3) of this AD, and there was no crack or rejectable indication.
