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13 Jun 2019 - EASA Issue LEAP-1B gearbox AD

EASA has, on 12 Jun 2019, issued an AD No.: 2019-0137 "ATA 72 – Engine – Transfer Gearbox Module Scavenge Screens – Inspection".

The AD requires inspection of Transfer Gearbox Modules (TGB) 1 and TGB 2 scavenge screens for any metallic particles, except fuzz (being any quantity of material which greatest dimension is 0.1016 mm / 0.004 in, or less) and machining curls. Apparently the inspection is simple to perform and takes 15 minutes.

This AD follows five commanded IFSD events following activation of the oil filter bypass light. Subsequent investigation identified the root cause as failure of the radial drive shaft bearing cage.

As this is an EASA AD, it is only applicable to European-registered aircraft. However, it is expected to be adopted worldwide. The AD follows a service bulletin issued by CFM on 1 Feb 2019.

CFM is redesigning the bearing in the radial drive shaft of the LEAP-1B and is planning to release it within months.

The radial drive shaft is part of the accessory drive train (ADT) which was developed for the LEAP by Safran Transmission Systems. The ADT, which takes power from the engine to drive other systems on the aircraft, also includes the accessory gearbox and the transfer gearboxes.

The LEAP-1A is unaffected by this issue.

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*** Updated 23 Nov 2020 ***

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