AD 2020-21-23 Describes The Unsafe Condition As Improperly Manufactured Horizontal Stabilizer Rear Attachment Bolts

The FAA is adopting a new airworthiness directive (AD) for Pilatus Aircraft Ltd. Models PC-12, PC-12/45, PC-12/47, and PC-12/47E airplanes.

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 improperly manufactured horizontal stabilizer rear attachment bolts. If not corrected, this could lead to fatigue failure of the bolts and loss of airplane control. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective December 7, 2020.

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 Pilatus Aircraft Ltd. Models PC-12, PC-12/45, PC-12/47, and PC-12/47E airplanes with a certain horizontal stabilizer rear attachment bolt installed. The NPRM published in the Federal Register on August 6, 2020 (85 FR 47716). The NPRM proposed to require replacing the horizontal stabilizer rear attachment bolts and was prompted by MCAI originated by the European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community. EASA issued AD No. 2019-0129, dated June 6, 2019 (referred to after this as “the MCAI”), to correct the unsafe condition on these products. The MCAI states:

• On the final assembly line, horizontal stabilizer rear attachment bolts were detected that had not received correct heat treatment. Subsequent investigation determined that certain parts, identified by FAUF, were improperly manufactured and consequently have reduced material properties.
• This condition, if not corrected, could lead to a fatigue failure of an affected part, possibly resulting in loss of control of the aeroplane.
• To address this potential unsafe condition, Pilatus issued the [service bulletin] SB to provide inspection and replacement instructions.
• For the reason described above, this [EASA] AD requires replacement of affected parts, and prohibits (re)installation thereof.

 
You may obtain further information by examining the MCAI in the AD docket on the internet at www.regulations.gov by searching for and locating Docket No. FAA-2020-0745.

FMI: www.regulations.gov