AD 2022-04-01 Describes The Unsafe Condition As Failure Of The Bearing Of The Upper Pulley Of The Belt Driven Reduction Gear

The FAA is adopting a new airworthiness directive (AD) for DG Flugzeugbau GmbH Model DG-1000T gliders and Schempp-Hirth Flugzeugbau GmbH Model Duo Discus T gliders with a Solo Kleinmotoren GmbH Solo Model 2350C or 2350D engine installed.

This AD was prompted by mandatory continuing airworthiness information (MCAI) issued by the aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as failure of the bearing of the upper pulley of the belt driven reduction gear resulting in separation of the propeller from the engine. This AD requires replacing a certain hex-nut and establishing a life limit for the ball bearing assembly. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective March 29, 2022.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to DG Flugzeugbau GmbH Model DG-1000T gliders and Schempp-Hirth Flugzeugbau GmbH Model Duo Discus T gliders with a Solo Kleinmotoren GmbH Solo Model 2350C or 2350D engine, all serial numbers, installed. The NPRM published in the Federal Register on December 1, 2021 (86 FR 68168). The NPRM was prompted by MCAI originated by the European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union. EASA issued EASA AD 2019-0029, dated February 8, 2019 (referred to after this as “the MCAI”), to address an unsafe condition on Solo Kleinmotoren GmbH Solo Model 2350B, 2350BS, 2350C, and 2350D engines.

The MCAI states:

• An occurrence was reported of failure of the bearing of the upper pulley of the belt driven reduction gear, resulting in separation of the propeller from the engine.
• This condition, if not corrected, could lead to similar occurrences, with possible reduced control of, and damage to, the aircraft.
• To address this potential unsafe condition, Solo redesigned the nut securing the pulley bearing on the axle and introduced a life time limit of 15 years for the reduction gear bearings.

For the reason stated above, this [EASA] AD requires replacement of affected parts with serviceable parts, and introduces a life limit for the affected ball bearings. You may examine the MCAI in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-1015.

FMI: www.regulations.gov