FAA Issues Airworthiness Directives for Diamond DA40 and Pilatus PC-12

The FAA published two notable proposed airworthiness directives in May 2026 affecting popular general aviation aircraft: a new NPRM targeting the Diamond DA40 family over a passenger door separation risk, and a supplemental NPRM revising applicability for Pilatus PC-12 windshield heating systems. Here is what owners and operators need to know.

AD 1: Diamond DA40 — Passenger Door Separation in Flight

FAA Docket: FAA-2026-4633

AD Number: 2026-09574 (Proposed Rule / NPRM)

Comment Deadline: June 29, 2026

Aircraft Affected

The Unsafe Condition

The FAA identified multiple in-service reports of passenger door separation during flight on DA40 variants. The root cause investigation pointed to deficiencies in the safety hook, latching mechanism, and door guide assembly — specifically corrosion and wear in these components over time.

An in-flight door separation is a serious emergency. Beyond the immediate structural and aerodynamic effects, it creates significant distraction and workload at a critical time.

What Compliance Requires

The proposed AD would mandate:

• Revise the Airplane Flight Manual (AFM) with updated operating limitations, emergency procedures, and normal operating procedures
• Inspect the passenger door latching mechanism, safety hook, latching bolts, front and rear door guide blocks, canopy warning light, carbon hinges, tension spring, retaining block, push button, latching mechanism spring, gas spring, and door frame
• Measure passenger door handle actuation force
• Install updated placards
• Replace components as necessary (hook assembly, retaining block, door guide blocks, gas spring, sealant)

For DA40 owners: This is a proposed rule — the comment period runs through June 29, 2026. Final compliance timelines will be established when the AD is adopted. However, it is worth performing a visual inspection of your door latching system now and documenting its condition. Contact Diamond Aircraft at (519) 457-4041 or your local Diamond service center for manufacturer guidance.

How to Stay Current on ADs for Your Aircraft

These proposed rules are open for public comment before becoming final. Owners have the opportunity to submit technical data or operational concerns during the comment period — a step that has historically influenced final compliance requirements.

VNE members: If you have your aircraft registered in your hangar, you can enable AD alerts in your account settings. When new ADs are issued that affect your aircraft, you will receive an email notification automatically.