By AeroCopilot Editorial Team
The FAA published on April 24, 2026 a final Airworthiness Directive adopting EASA AD 2025-0092 for the Dassault Falcon 7X with modification M1000 incorporated — commercially designated Falcon 8X. The rule, published in the Federal Register as document 2026-08031, requires incorporation of modification M2138 (a MAIC software update) and revision of the AFM procedures following a report of a silent inboard-slat extension failure during landing, with no Crew Alerting System (CAS) indication. The condition was classified as unsafe by the European authority in April 2025 and is now mandatory on the U.S. registry and in countries that validate FAA ADs.
What Triggered the FAA Action
The FAA was notified, via EASA, of an in-service event in which the inboard slats on a Falcon 7X failed to extend during landing without any CAS message presented to the crew. Engineering analysis traced the issue to a software defect in the Maintenance and Avionics Interface Computer (MAIC) running DFCS standard 4.1.3, which suppresses the "FCS: SLAT INB EXTEND FAIL" CAS message when the failure occurs.
Inboard slats — the leading-edge devices closest to the fuselage — are critical lift augmentation surfaces during approach and landing. The Vref computed by the FMS assumes slats extended; when they do not deploy and the alert is suppressed, the aircraft approaches with reduced lift margin while the crew has no trigger to apply the slats-retracted procedure.
Regulatory timeline:
- Aug 2022 — EASA Emergency AD 2022-0161-E (initial AFM revision)
- Sep 2022 — FAA AD 2022-18-18 (87 FR 54131), corresponding interim action
- Apr 2025 — EASA AD 2025-0092, final directive requiring mod M2138 and revised AFM
- Mar 2026 — FAA NPRM (Docket FAA-2026-2293)
- Apr 24, 2026 — FAA final AD 2026-08031 adopting EASA AD 2025-0092
The roughly three-year span between the original 2022 emergency action and the M2138 software fix reflects the complexity of the Falcon 7X DFCS architecture, in which CAS alerting logic is shared between the MAIC and the DFCS.
Why the Slat Failure Is "Silent"
In normal operation, the CAS should display "FCS: SLAT INB EXTEND FAIL" whenever the inboard slats fail to extend, prompting the slats-retracted approach procedure: increased Vref, landing performance reassessment, and consideration of an alternate runway. The software defect omits that message. As a result, the FMS-calculated Vref still assumes extended slats, the crew receives no cue to reconfigure, and on a contaminated runway, in crosswind, or during a wind-shear approach, the reduced margin can degrade into loss of control. A failure that suppresses a safety alert is treated as a latent unsafe condition — present without crew awareness.
Modification M2138 and Prerequisites
The AD requires three principal actions to restore the safe condition:
- MAIC software upgrade — Dassault modification M2138 corrects DFCS 4.1.3 logic and restores the CAS message
- Prerequisite mods — Either M1968 (MAIC update) or M1655 (DFCS standard 4.1.1) must be incorporated before M2138
- AFM revision — Incorporation of the revised slat-failure procedures (AFM revision 7 or later)
M2138 is a software-only modification — no mechanical components are replaced. The upgrade is performed via the MAIC maintenance port using Dassault-specific tooling. Aircraft not yet at M1968 or M1655 must receive those modifications first, in the sequence specified by the applicable Service Bulletin.
The revised AFM procedures cover indirect detection of a slat failure via cross-checking FMA, configuration indications, and performance; manual computation of an adjusted Vref for retracted slats; landing performance reassessment for contaminated or short runways; and go-around criteria when configuration is suspect.
Costs, Compliance Times, and Affected Fleet
FAA cost estimates per aircraft:
- Labor — up to 24 hours at US$85/hr = US$2,040
- Parts/tooling — up to US$2,860
- Per-aircraft total — up to US$4,900
- U.S. fleet total — up to US$122,500 across 25 aircraft
All affected aircraft are Falcon 7X with modification M1000 incorporated. A portion of the cost may be absorbed under Dassault warranty for operators still within coverage. Special tooling rents between US$929 and US$981 per day depending on the modification. The compliance window mirrors EASA AD 2025-0092: M2138 must be incorporated at the next scheduled inspection after the effective date. Operators should coordinate slot and tooling availability with an authorized Dassault service center.
Considerations for Operators Outside the U.S.
The Falcon 7X is widely operated in international long-range business aviation, including South American fleets working under regimes equivalent to FAR Part 135 and Part 91 Subpart K. Where the State of Design is France (via EASA), local civil aviation authorities typically validate the EASA AD, and the additional FAA action strengthens the technical basis for prompt local adoption. Prudent operators do not wait for a domestic directive — they begin scheduling M2138 incorporation against the EASA AD already in force.
Until M2138 is embodied, crews should:
- Brief the AFM slat-extension-failure procedure on every approach
- Maintain active configuration awareness during the landing checklist, confirming visually or via secondary indication that slats have extended
- Add speed margin on final if any doubt exists about slat configuration
- Favor longer, dry runways during the transition period
Frequently Asked Questions
Does the AD apply to all Falcon 7X variants? No. It applies specifically to Falcon 7X with modification M1000 incorporated (Falcon 8X). The FAA noted this is interim action; future rulemaking may expand applicability to Falcon 7X without M1000.
How long does M2138 incorporation take? The FAA estimates up to 24 hours per aircraft including prerequisite mods. As a software-only change, typical aircraft downtime is 2–3 working days including logistics, tooling, and post-mod tests.
Does the modification affect performance or weight? No. M2138 changes only MAIC alerting logic. Empty weight, CG envelope, performance, and AFM limitations are unchanged.
What happens if compliance is missed? Non-compliance with an AD renders the aircraft unairworthy until rectified. For commercial operators this directly affects the operating certificate and can suspend revenue activity until conformity is restored.
Information current as of publish date; pilots responsible for verifying with current FAA/NTSB sources before flight.
AeroCopilot tracks FAA, EASA, and partner-authority ADs across business jet fleets and surfaces fleet-specific alerts during pre-flight planning. For Falcon 7X/8X operators, integrating M2138 status into the pre-flight check is recommended until the entire fleet is modified.
Sources
- Federal Register — Airworthiness Directives; Dassault Aviation Airplanes, document 2026-08031, April 24, 2026 (final AD adopting EASA AD 2025-0092)
- EASA AD 2025-0092 — Slat Inboard Extension Failure (originating directive)
- Dassault Aviation Falcon 7X AMM and Service Bulletins covering modifications M1655, M1968, and M2138
- FAA Airworthiness Directives Database — Docket FAA-2026-2293 and prior AD 2022-18-18 (Amendment 39-22169, 87 FR 54131)