FAA Proposes AD Requiring Software Update on All Pilatus PC-24 Airplanes to Fix Flight Director Errors
Why It MattersReplacing a manual-only interim fix with a software installation shows regulators treating avionics logic faults as hardware-class corrections, which pushes cost and downtime onto operators and the type's service network.
What happened
The Federal Aviation Administration has proposed an airworthiness directive for all Pilatus Aircraft Ltd. Model PC-24 airplanes. The notice of proposed rulemaking was published in the Federal Register on November 4, 2026 (document 2026-22496, 91 FR 69506; docket FAA-2026-13798), and the FAA must receive comments by December 21, 2026.
The proposal would supersede AD 2025-20-02, which required operators to incorporate a temporary revision into the airplane flight manual, revising the Abnormal Procedures Section. The FAA described that action as an interim measure. Since AD 2025-20-02 was issued, updated Primus APEX DFZ Build 6.0 software has been developed, and Pilatus has issued service information with installation instructions. Pilatus has also issued AFM-TR 02371-081, which provides operational instructions applicable after the software is installed.
The proposed AD would require installing the updated software and then incorporating the revised operational instructions into the AFM. It retains the requirement to incorporate the existing AFM instructions. The unsafe condition is heading splits that can cause errors in flight director calculations, resulting in lateral offsets to the desired approach course.
The action follows EASA AD 2026-0149, dated July 28, 2026, which superseded EASA AD 2024-0240 of December 10, 2024. The earlier EASA directive had addressed an occurrence of an inaccurate flight director calculation on approach.
How it unfolded
Deadline for the FAA to receive public comments on the proposal.
FAA publishes the proposed AD in the Federal Register (docket FAA-2026-13798).
EASA issues AD 2026-0149, superseding AD 2024-0240.
FAA issues AD 2025-20-02, requiring a temporary AFM revision to the Abnormal Procedures Section as an interim measure.
EASA issues AD 2024-0240, addressing an occurrence of an inaccurate flight director calculation on approach.
Industry impact & what to watch
The sequence here is a common one for avionics-related unsafe conditions: a manual-based workaround is mandated first, and a software correction follows once the manufacturer has one ready. The FAA's own description of the earlier AD as interim makes this proposal the intended end state, not an additional layer.
For a light-jet type operated largely by owner-operators, charter and fractional-style fleets, a mandatory software installation means scheduled shop time at a service facility, whereas an AFM revision costs only a paperwork change. The practical load falls on the type's service network and on operators who depend on high aircraft availability.
The next milestone is the December 21, 2026 comment deadline. After it, the FAA can finalize the AD, and the final rule will set the compliance time that determines how quickly the fleet has to be scheduled for the update.
