AD/CON/56 Amdt 2 Number Two Crankcase Main Bearing Integrity (Cth)

AIRWORTHINESS DIRECTIVE On the commencement date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below repeals Airworthiness Directive (AD) AD/CON/56 Amdt 1 and issues the following AD under subregulation 39.001 (1) of CASR and subsection 33 (3) of the Acts Interpretation Act 1901. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct an unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Continental Aerospace Technologies (Continental Motors) Piston Engines AD/CON/56 Amdt 2 Number Two Crankcase Main Bearing Integrity 16/2021

Applicability: Continental Motors Model TSIO-520BE engines Serial Numbers 528001 through 528337. Requirement: 1. Inspect crankcase for end play in accordance with Teledyne Continental Motors (TCM) Service Bulletin (SB) M89-14 Section A as in force on the commencement date of this AD. 2. Carry out thru-bolt torque check in accordance with TCM SB M89-14 Section B as in force on the commencement date of this AD. 3. Inspect number two crankcase main bearing in accordance with TCM SB M89-14 Section C as in force on the commencement date of this AD. Note 1: The repetitive checks and inspections detailed in Requirements No. 1 and No. 3 may be discontinued following disassembly of the crankcase assembly to a depth sufficient to inspect the crankcase mating flanges for evidence of fretting, and new bearings are installed. Note 2: United States of America Federal Aviation Administration (FAA) Airworthiness Directive 89-14-01 is the basis for this AD. Compliance: 1. Before further flight after the commencement date of this AD, unless accomplished previously, and thereafter at intervals not to exceed 25 hours' time in service. 2. Before further flight after the commencement date of this AD, unless accomplished previously. 3. Before further flight after the commencement date of this AD unless accomplished previously, and thereafter at intervals not to exceed 200 hours' time in service. This AD commences on 20 August 2021. Background: Advice from the engine manufacturer indicates, loss of thru-bolt torque results in fretting of the crankcase mating flanges and possible migration of the number two main bearing. Until that fretting is addressed, the integrity of the number two main bearing is suspect and repetitive inspections as detailed in TCM SB M89-14 is justified. Amendment 1 introduced terminating action. Amendment 2 removes obsolete references and makes minor editorial changes to reflect current requirements.