AD 2020-22-14 Requires Engine Modification By Installing A Waste Gate Controlrod Fail-Safe Bridge And New Spring-Loaded Circlip

The FAA is superseding Airworthiness Directive (AD) 2018-07-16 for all Austro Engine GmbH model E4 and E4P diesel piston engines. AD 2018-07-16 required initial and repetitive replacement of the waste gate controller and the control rod circlip.

This AD retains the requirements of AD 2018-07-16 and requires engine modification by installing a waste gate controlrod fail-safe bridge and new spring-loaded circlip that terminates the initial and repetitive replacement requirements of AD 2018-07-16. This AD was prompted by the development of a modification of the waste gate control rod by adding a fail-safe bridge and spring-loaded circlip. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective December 10, 2020.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2018-07-16, Amendment 39-19247 (83 FR 15733, April 12, 2018), (“AD 2018-07-16”). AD 2018-07-16 applied to all Austro Engine GmbH model E4 and E4P diesel piston engines. The NPRM published in the Federal Register on October 23, 2019 (84 FR 56707). The NPRM was prompted by the development of a modification of the waste gate control-rod by adding a fail-safe bridge and spring-loaded circlip. The NPRM proposed to retain all of the requirements of AD-2018-07-16. The NPRM also proposed engine modification by installing the waste gate control rod failsafe bridge and new spring-loaded circlip as terminating action for the initial and repetitive replacement of the waste gate controller and the control rod circlip. The FAA is issuing this AD to address the unsafe condition on these products.

The European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA AD 2018-0125, dated June 6, 2018 (referred to after this as “the MCAI”), to address the unsafe condition on these products. The MCAI states:

• Occurrences were reported where, on some engines, turbocharger waste gate control rods were found broken and/or disconnected. Investigation results indicate that these failures were due to insufficient fatigue life or improper handling of the waste gate control rod and improper installation of the non-spring-loaded circlip.
• These conditions, if not corrected, could lead to improper operation of the waste gate with consequent engine power loss, possibly resulting in reduced control of the aeroplane.
• To address this potential unsafe condition, Austro Engine designed a new spring loaded circlip and published MSB-E4-022 (later revised), introducing a life limit for the affected waste gate controllers and circlips. Consequently, EASA issued AD 2017-0250, requiring implementation of those life limits, and prohibiting reinstallation of non-spring-loaded circlips.
• Since that [EASA] AD was issued, Austro Engine developed a modification, which allows replacing the waste gate controller and the circlip on condition, and issued the MSB accordingly. For the reason stated above, this [EASA] AD retains the requirements of EASA AD 2017-0250, which is superseded, and requires an engine modification by installing a waste-gate control-rod fail-safe bridge and a new circlip, which cancels the life limitations.

You may obtain further information by examining the MCAI in the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2019-0664.

FMI: www.regulations.gov