AD 2021-22-21 Identifies The Unsafe Condition As Failure Of A Circuit Breaker (CB) Switch

The FAA is adopting a new airworthiness directive (AD) for all ASI Aviation (type certificate previously held by Reims Aviation S.A.) Model F406 airplanes.

This AD was prompted by 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 failure of a circuit breaker (CB) switch. This AD requires replacing certain CB switches and establishing a life limit for the CB switches. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective January 3, 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 all ASI Aviation (type certificate previously held by Reims Aviation S.A.) Model F406 airplanes. The NPRM published in the Federal Register on August 27, 2021 (86 FR 48067). 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 AD 2019-0015, dated January 29, 2019 (referred to after this as “the MCAI”), to correct an unsafe condition on ASI Aviation (type certificate previously held by Reims Aviation S.A.) Model F406 airplanes.

The MCAI states:

• After the Federal Aviation Administration issued AD 2005-20-25 [70 FR 59237, October 12, 2005], applicable to Cessna 400 series aeroplanes equipped with certain avionics bus CB switches, it was determined that, due to design commonality, one of the affected avionics bus CB switches, P/N [part number] CM3589-50, was also installed on Reims F 406 aeroplanes.
• This condition, if not corrected, could lead to smoke and/or burning smell in the cockpit, possibly resulting in reduced control of the aeroplane.
• To address that potential unsafe condition, RAI issued SB [service bulletin] F406-62 to provide instructions to remove certain switches from service. Consequently, EASA issued AD 2006-0134 to require identification of the date code of P/N CM3589-50 CB switches and, depending on findings, replacement with improved design CB switches,
• P/N 4061-2400-1. That [EASA] AD also imposed a life limit on the affected CB switches P/N CM3589-50.
• Since that [EASA] AD was issued, in-service occurrences of smoke and burning smell in the cockpit have been reported on F 406 aeroplanes. Technical investigations revealed that these were due to failure of CB switches P/N CM3589-20, which are used to control the propeller de-icing circuit. Prompted by these events, ASI Aviation issued the applicable SB (as defined in this [EASA] AD) to provide instructions to replace the affected parts with serviceable parts.
• For the reasons described above, this [EASA] AD retains the requirements of EASA AD 2006-0134, which is superseded, expands the range of affected parts, and requires replacement of P/N CM3589-20 CB switches with improved design CB switches P/N 406E2450-00000-100. This [EASA] AD also replaces the previous life limit, 1000 flight hours (FH) for certain P/N CM3589-50 CB switches, with a 6 year calendar time life limit, and also imposes that limit on the improved design CB switches.

You may examine the MCAI in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-0714.

FMI: www.regulations.gov