AD 2021-18-13 Airworthiness Directives; General Electric Company Turbofan Engines

This AD applies to General Electric Company (GE) CF34-8C1, CF34-8C5, CF34-8C5A1, CF34-8C5B1, CF34-8C5A2, CF34-8C5A3, CF34-8E2, CF34-8E2A1, CF34-8E5, CF34-8E5A1, CF34-8E5A2, CF34-8E6, and CF34-8E6A1 model turbofan engines with an outer shell combustion liner (combustion outer liner shell), part number (P/N) 4124T04G04, P/N 4124T04G05, or P/N 5159T35G02, installed.

Comply with this AD within the compliance times specified, unless already done.

(1) For an affected engine with a combustion outer liner shell that on the effective date of this AD has accumulated 17,500 flight hours (FHs) or greater time since new (TSN), or time since repair (TSR), perform an initial borescope inspection (BSI) or visual inspection of the combustion outer liner shell for cracks before accumulating 500 engine FHs after the effective date of this AD. (i) For GE CF34-8C engines, inspect using the Accomplishment Instructions, paragraphs 3.A.(4) and 3.A.(5), of GE CF34-8C Alert Service Bulletin (SB) 72-A0335 R02, dated February 25, 2020 (CF34-8C Alert SB 72-A0335). (ii) For GE CF34-8E engines, inspect using the Accomplishment Instructions, paragraphs 3.A.(4) and 3.A.(5), of GE CF34-8E Alert SB 72-A0221 R02, dated February 25, 2020 (CF34-8E Alert SB 72-A0221). Note 1 to paragraph (g)(1): GE has identified the service information as an “Alert Service Bulletin,” which is stated only in the body of the Alert SB. (2) For an affected engine with a combustion outer liner shell that on the effective date of this AD has accumulated 17,499 FHs or fewer TSN or TSR, before accumulating 500 engine FHs after the combustion outer liner shell has accumulated 17,500 FHs TSN or TSR, perform an initial BSI or visual inspection on the combustion outer liner shell for cracks. (i) For GE CF34-8C engines, inspect using the Accomplishment Instructions, paragraphs 3.A.(4) and 3.A.(5), of CF34-8C Alert SB 72-A0335. (ii) For GE CF34-8E engines, inspect using the Accomplishment Instructions paragraphs 3.A.(4) and 3.A.(5), of CF34-8E Alert SB 72-A0221. (3) For an affected engine with a combustion outer liner shell for which it is not possible to determine the TSN or TSR, use the engine FHs since new to determine when to perform the initial BSI or visual inspection. (4) After the effective date of this AD, and after the initial inspection required by paragraph (g)(1) or (2) of this AD, re-inspect or remove the combustion outer liner shell using inspection criteria as follows: (i) For GE CF34-8C engines, use Table 1 of CF34-8C Alert SB 72-A0335. (ii) For GE CF34-8E engines, use Table 1 of CF34-8E Alert SB 72-A0221.

This AD was prompted by two in-flight engine shutdowns (IFSDs) that occurred as a result of failures of the combustion outer liner shell. The FAA is issuing this AD to prevent failure of the combustion outer liner shell. The unsafe condition, if not addressed, could result in burn-through of the low-pressure turbine case, engine fire, and damage to the airplane.

None.