AD 2023-20-03 Airworthiness Directives; Austro Engine GmbH Engines

Makes named: austro. Models named: E4, E4P. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Austro Engine GmbH Model E4 and E4P engines with a serial number listed in Tables 1, 2, 3, and 4 of Austro Engine GmbH Mandatory Service Bulletin No. MSB-E4-039/1, Revision 1, dated April 24, 2023 (MSB-E4-039/1).

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

(1) For all affected engines, within the applicable compliance times specified in Table 1 to paragraph (g)(1) of this AD, perform an oil analysis in accordance with paragraph 2., Technical Details, Engine Oil Analysis of MSB-E4-039/1, and do not return the engine to service until the results of the oil analysis have been determined. Table 1 to Paragraph ( g )(1)—Oil Analysis for All Affected Engines Engine group Compliance time Interval Group 1 and Group 3 Within 15 flight hours (FHs) from the effective date of this AD Before exceeding 50 FHs since last oil analysis. Group 2 and Group 4 Within 25 FHs from the effective date of this AD Before exceeding 100 FHs since last oil analysis. (2) Thereafter, repeat the oil analysis required by paragraph (g)(1) of this AD before exceeding the applicable interval specified in Table 1 to paragraph (g)(1) of this AD. (3) Following each repetitive oil analysis, the engine may be returned to service for no more than the applicable interval specified in Table 1 to paragraph (g)(1) of this AD, until receipt of the oil analysis result. (4) If the result of any oil analysis required by paragraph (g)(1) of this AD indicates the aluminum content of the oil is greater than the limit specified in paragraph 2., Technical Details, Engine Oil Analysis, Table 5—Oil check analysis—Aluminum PPM allowable of MSB-E4-039/1, before further flight, replace the pistons, piston rings, con-rods assembly, and crankcase, or replace the engine core in accordance with paragraph 2., Technical Details, Engine core replacement; or Pistons, piston rings, crankcase and con-rod assy replacement; as applicable, of MSB-E4-039/1. (5) For Group 3 and Group 4 engines, within the applicable compliance times specified in Table 2 to paragraph (g)(5) of this AD, replace the pistons, piston rings, and con-rods assembly, or replace the engine core in accordance with paragraph 2., Technical Details, Engine core replacement; or Pistons, piston rings and con-rod assy replacement, as applicable, of MSB-E4-039/1. Table 2 to Paragraph ( g )(5)—Replacement for Groups 3 and 4 Engines Engine group Compliance time Group 3 Before exceeding 900 FHs since new, or within 15 FHs after the effective date of this AD, whichever occurs later. Group 4 Before exceeding 1,000 FHs since new, or within 25 FHs after the effective date of this AD, whichever occurs later. Note 1 to paragraph (g)(5): FHs since new indicated in Table 2 to paragraph (g)(5) of this AD are FHs accumulated by the engine since first installation on an airplane or since last overhaul as of the effective date of this AD.

This AD was prompted by reports of piston failures and the determination that certain batches of pistons were manufactured with a dimensional deviation in the piston pin bore and piston diameter. The FAA is issuing this AD to prevent piston failure. The unsafe condition, if not addressed, could result in loss of oil, loss of engine power, and reduced control of the airplane.

None.