AD 2021-01-05 Requires Modifying The Electrical Harness Installation

The FAA is adopting a new airworthiness directive (AD) for certain Pilatus Aircraft Ltd. (Pilatus) Model PC-24 airplanes.

This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI identifies the unsafe condition as electrical harness installations on PC-24 airplanes that are not in compliance with the approved design. This unsafe condition could lead to wire chafing and potential arcing or failure of wires having the incorrect length, possibly resulting in loss of system redundancy, or generation of smoke and smell, or loss of power plant fire protection function. This AD requires modifying the electrical harness installation. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective March 30, 2021.

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 certain serial-numbered Pilatus Model PC-24 airplanes. The NPRM published in the Federal Register on September 17, 2020 (85 FR 58002). The NPRM 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 Union. EASA has issued EASA AD No. 2020-0158, dated July 16, 2020 (referred to after this as “the MCAI”), to address the unsafe condition on these products.

The MCAI states:

• During production, electrical harness installations on some PC-24 aeroplanes were found not to comply with the approved design.
• This condition, if not corrected, could lead to wire chafing and potential arcing, or to failure of wires having the incorrect length, possibly resulting in loss of system redundancy, or generation of smoke and smell, or loss of power plant fire protection function.
• To address this potential unsafe condition, Pilatus issued the [service bulletin] SB, providing instructions to improve the electrical harness installations in the nose bay, cockpit, fuselage, wing fairing and rear fuselage areas.
• For the reason described above, this [EASA] AD requires modification of the electrical harness installations.

The incorrect length wires are too short in length and do not have appropriate slack, which could lead to wires being pulled loose from the terminals during flight or ground operation. Generation of smell refers to the smell from electrical arcing. You may examine the MCAI in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-0818.

In the NPRM, the FAA proposed to require modifying the electrical harness installation. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov