FAA Orders Door Checks After Diamond Aircraft Doors Could Pop Open
Published Date: 11/2/2026
Rule
Summary
If you own or fly a Diamond DA 40, DA 40 F, or DA 40 NG airplane, listen up! The FAA found some passenger doors might pop open mid-flight, so they’re making you update your flight manual, check and fix door parts, and add safety signs. These fixes start December 7, 2026, and could cost some money but keep everyone safer in the sky.
Analyzed Economic Effects
4 provisions identified: 1 benefits, 3 costs, 0 mixed.
Mandatory safety actions and inspections
If you own or operate a Diamond DA 40, DA 40 F, or DA 40 NG airplane, you must revise the airplane flight manual and complete required inspections and modifications within 100 hours time-in-service (TIS) or 100 days after December 7, 2026. The AD requires measurements of the door-handle force, placards, and replacing items like the gas spring or hook assembly when specified; some replacements must be done before further flight or within 12 months depending on measured force thresholds (for example, replace the gas spring within 12 months if certain low-force conditions are found).
Estimated compliance and repair costs
The FAA estimates per-airplane: AFM revision costs $85; initial inspection costs $331 (3 work-hours at $85/hour plus $76 parts); repetitive inspections cost $85 per inspection. On-condition replacement cost examples: gas spring about $659 total, hook assembly about $824 total, retaining block about $251 total, door guide block about $291 total, and door sealant about $100 total.
Who is covered and total U.S. impact
This AD applies to all Diamond Aircraft Industries Inc. Model DA 40, DA 40 F, and DA 40 NG airplanes certificated in any category; the FAA estimates it affects 987 airplanes on the U.S. registry.
Credit if you already complied earlier
If you already performed the required actions before December 7, 2026 using Diamond Aircraft Mandatory Service Bulletin MSB 40-103/MSB F4-042/MSB D4-114/MSB 40NG-084 REV. 1 (dated May 15, 2025) or REV. 0 (dated March 20, 2025), you may take credit for the AD actions and need not repeat them.
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