AD 2022-03-09 Requires Replacing Affected GPS Receivers

The FAA is adopting a new airworthiness directive (AD) for certain Sikorsky Aircraft Corporation Model S-76D helicopters.

This AD was prompted by reports that certain Thales global positioning system (GPS) satellite based augmentation system (SBAS) receivers provided, under certain conditions, erroneous outputs on aircraft positions. This AD requires replacing affected GPS receivers and prohibits installing those GPS receivers. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective March 17, 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 Sikorsky Aircraft Corporation Model S-76D helicopters with a GPS TopStar 200 LPV receiver part number (P/N) C17149HA01 installed. The NPRM published in the Federal Register on November 16, 2021 (86 FR 63322). The NPRM was prompted by reports that certain Thales GPS SBAS receivers provided, under certain conditions, erroneous outputs on aircraft positions. The unsafe condition, if not addressed, could result in controlled flight into terrain and loss of control of the helicopter. Therefore, the NPRM proposed to require replacing each affected GPS receiver and prohibit installing an affected GPS receiver on any helicopter. The FAA is issuing this AD to address the unsafe condition on these products.

The European Aviation Safety Agency (now European Union Aviation Safety Agency) (EASA), which is the Technical Agent for the Member States of the European Union, issued EASA AD 2019-0004, dated January 11, 2019, and corrected on January 17, 2019 (EASA AD 2019-0004), to correct an unsafe condition for Thales AVS France SAS (Thales), formerly Thales Avionics SAS, GPS/SBAS receivers, Topstar 200 LPV, P/N C17149HA01 and C17149JA02, using SBAS, which are known to be installed on, but not limited to, certain Model ATR 42-500 and ATR 72-212A aeroplanes and Sikorsky Model S-76D helicopters. EASA advises of reports indicating that Thales GPS SBAS receivers provided, under certain conditions, erroneous outputs on aircraft positions. EASA AD 2019-0004 requires actions to prevent compromise of the safety margins when the receiver is used for Localizer Performance with Vertical guidance (LPV) and/or RNP-AR (Required Navigation Performance–Authorization Required) operations. Following the issuance of EASA AD 2019-0004, the FAA issued AD 2020-08-02, Amendment 39-21108 (85 FR 20586, April 14, 2020), to address the unsafe condition on these products.

After the issuance of EASA AD 2019-0004, EASA issued related EASA AD 2021-0013, dated January 13, 2021, in response to a software update that was developed to ensure correct navigational performance of certain Thales GPS SBAS receivers installed on ATR-GIE Avions de Transport Régional, formerly EADS ATR–Alenia, Aerospatiale Matra ATR–ALENIA, Aerospatiale–Alenia, Aerospatiale–Aeritalia, Model ATR 42-500 and ATR 72-212A aeroplanes. The FAA subsequently issued AD 2021-19-13, Amendment 39-21731 (86 FR 54801, October 5, 2021), to address the unsafe condition on these products.

FMI: www.regulations.gov