AD NUMBER: 2018-03-16

PRODUCT: Stemme AG Model Stemme S10-VT gliders (type certificate previously held by Stemme GmbH & Co. KG).

ACTION: Final Rule.

SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2017-10-11 for the products listed above.

This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and address an unsafe condition on an aviation product.

The MCAI describes the unsafe condition as certain propeller front transmission gear wheels having insufficient material strength because of improper heat treatment during manufacturing. The FAA is issuing this AD to require actions to address the unsafe condition on these products and to add Stemme AG Model Stemme S 12 gliders to the Applicability section.

DATES: This AD is effective March 20, 2018.

COST: The FAA estimates that there are 51 of both glider types registered, but there are still only 14 serial numbers of the part number 11AG front gearbox. Therefore, the most gliders that will be affected remains 14. According to Stemme AG, there are a total of 4 of the affected front gearboxes on both glider types of U.S. registry (2 for each model).

It will take an estimated 10 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $85 per work-hour. Required parts will cost about $2,000 per product. Based on these figures, the cost of compliance is estimated to be $2,850 per product.

According to the manufacturer, some of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected individuals. The FAA does not not control warranty coverage for affected individuals. As a result, all costs have been included in the cost estimate.

FMI: AD