Airworthiness Directive · Amendment 39-21539 · Engine controls
CFM International, S.A. Turbofan Engines
This AD applies to CFM International S.A. (CFM) LEAP-1B21, -1B23, -1B25, -1B27, -1B28, -1B28B1, -1B28B2, -1B28B3, -1B28B2C, -1B28BBJ1, and -1B28BBJ2 model turbofan engines with a pressure sub-system (PSS) unit with a serial number (S/N) listed in Additional Information, Paragraph 6.A. Table 1 of CFM Service Bulletin (SB) LEAP-1B-73-00-0038-01A-930A-D, Issue 002-00, dated 2021-04-25 (SB LEAP-1B-73-0038), installed.
The FAA is adopting a new airworthiness directive (AD) for certain CFM International, S.A. (CFM) LEAP-1B model turbofan engines. This AD was prompted by multiple reports of pressure sub-system (PSS) unit faults due to pressure transducer corrosion following extended storage periods. For an engine in service, this AD requires checks for engine maintenance messages related to the pressure transducer and, depending on the results of the check, replacement of the PSS unit before further flight. The AD requires this repetitive check for faults prior to each flight until the PSS has accumulated at least 15 hours of electrical power. For an engine not in service, this AD requires applying electrical power to the PSS unit before further flight. The FAA is issuing this AD to address the unsafe condition on these products.
(1) For an engine in service on the effective date of this AD that has accumulated fewer than 15 hours of electrical power applied to the PSS unit within the past 90 days, perform one of the following actions:
(i) Prior to each flight, perform a check for the engine maintenance messages listed in the Accomplishment Instructions, paragraph 5.B.(2)(a) 2, of SB LEAP-1B-73-0038, related to the pressure transducer, until the PSS unit has accumulated 15 hours or more of electrical power within the previous 90 days; or
(ii) Before further flight, apply electrical power to the PSS unit in accordance with the Accomplishment Instructions, paragraph 5.A.(3)(a) 1, of SB LEAP-1B-73-0038, until the PSS unit has accumulated 15 hours or more of electrical power within the past 90 days.
(2) For an engine in service on the effective date of this AD that has accumulated 15 hours or more of electrical power applied to the PSS unit within the previous 90 days, within 5 flight cycles of the effective date of this AD, perform a one-time check for the maintenance messages listed in the Accomplishment Instructions, paragraph 5.B.(2)(a) 2, of SB LEAP-1B-73-0038, related to the pressure transducer.
(3) For an engine not in service on the effective date of this AD that has accumulated fewer than 15 hours of electrical power applied to the PSS unit within the past 90 days, before further flight, apply electrical power to the PSS unit in accordance with the Accomplishment Instructions, paragraph 5.A.(3)(a) 1, of SB LEAP-1B-73-0038, until the PSS unit has accumulated 15 hours or more of electrical power within the previous 90 days.
(4) For an engine not in service on the effective date of this AD that has accumulated 15 hours or more of electrical power applied to the PSS unit within the previous 90 days, before further flight, perform a check for the engine maintenance messages using the Accomplishment Instructions, paragraphs 5.A.(3)(b)1 through 5, of SB LEAP-1B-73-0038, related to the pressure transducer.
(5) After accumulating 15 hours of electrical power on the PSS unit as required by paragraph (g)(1)(ii) or (g)(3) of this AD, before further flight, perform a check for the engine maintenance messages using the Accomplishment Instructions, paragraphs 5.A.(3)(b) 1 through 5, of SB LEAP-1B-73-0038, related to the pressure transducer.
(6) If any engine maintenance messages are found by the checks required by paragraph (g)(1)(i), (2), (4), or (5) of this AD, before further flight, replace the PSS unit with a PSS unit eligible for installation.
(1) For the purpose of this AD, an “in service” engine is any of the following:
(i) An engine installed on an airplane that was delivered prior to November 18, 2020, that, as of the effective date of this AD, has completed the Operational Readiness Flight in accordance with paragraph (m) of FAA AD 2020-24-02 (85 FR 74560, November 20, 2020); or
(ii) An engine installed on an airplane delivered after November 18, 2020.
(2) For the purpose of this AD, hours of electrical power on the PSS unit is the total amount of time that voltage was applied to the PSS unit either on-wing or on a bench in segments of no less than 15 minutes. If the voltage-time is not available, use the run time of the engine on which the PSS unit is installed.
(3) For the purpose of this AD, a “PSS unit eligible for installation” is any of the following:
(i) A PSS unit that is cleared in accordance with the criteria in the Accomplishment Instructions, paragraph 5.B.(3), of SB LEAP-1B-73-0038; or
(ii) A PSS unit with an S/N not listed in Additional Information, Paragraph 6.A. Table 1 of SB LEAP-1B-73-0038.
After the effective date of this AD, do not install on any engine a PSS unit unless it is a PSS unit eligible for installation as defined in paragraph (h)(3) of this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
