The FAA has 15 October 2025 the AD 2025-20-18 for Continental TAE 125-02-125 published engines, Effective from 30 October 2025. Key points: one-off coolant analysis and, depending on the findings, System flushing or Cylinder head replacement.
What does this mean specifically for EASA/EU operators?

What is technical about?

  • Background: Several reports on Cracks in cylinder heads (TAE 125-02-125) with risk for Coolant leak into the combustion chamber → power drop until engine failure.
  • Mandatory measure (FAA-AD 2025-20-18): One-off Coolant analysis according to Continental SB CG 125-1030 P1 (Rev. 4). If the limit values are exceeded:
    • Aluminum/fluoride over limit → Replace cylinder head + Rinse/refill system.
    • Other Limits Exaggerated → Rinse cooling circuit + refill.
  • Installation ban: After the effective date, only "serviceable" Cylinder heads are installed.

Source: Federal Register AD 2025-20-18 (Docket FAA-2025-3432), effective 30.10.2025. See ‘Dates’, ‘AD Requirements’ and ‘Installation Prohibition’ in full text. Source linked below.

What is the current situation in the EU/EASA world?

  • EASA-AD 2024-0236 (effective since 17.12.2024) already addressed Coolant contamination on TAE 125, with reference to previous revisions of the same Continental SB. Similar in content (analysis/flushing), but without Now introduced by the FAA Specific exchange obligation in case of Al/fluoride exceedance according to Rev. 4.
  • N-registered aeroplanes in Europe, the FAA-AD must: from 30.10.2025 fulfilling.
  • EASA registered aircraft: Until an EASA follow-up AD appears, 2024-0236 binding. Recommendation from an operator/safety point of view: Rev. 4 limits (FAA level) proactive take over.

Sources: EASA AD 2024-0236 (TAE 125-02-125; effective 17.12.2024), FAA AD 2025-20-18 (effective 30.10.2025). Downstairs on the left.

Practice checklist for operators & clubs (ELA1)

  1. Clarify document status: Engine type/series number, last coolant maintenance, analyses already carried out and their limits.
  2. Take the sample: According to SB CG 125-1030 P1, Rev. 4 (clean bottle, warm, label correctly).
  3. Test laboratory results:
    • Aluminium/fluoride > Limit values → Replace cylinder head, Rinse system, refill (G40 recommended).
    • Other limits > Limit → rinsing + Refill, then short interval check.
  4. Document limit values/revision: Record in the logbook whether Rev. 4 has been assessed.
  5. Spare parts/lead time: Check cylinder head availability, installation only ‘serviceable part’.
  6. N-Reg in EU: FAA Compliance up to 5 FH after effectiveness (if ≥50 FH since last coolant change), otherwise up to 50 FH – see AD compliance.

sources

  • FAA - Federal Register: AD 2025-20-18 (TAE 125-02-125), published 15.10.2025, effective 30.10.2025. (Full text, ‘Dates’, ‘AD Requirements’)
  • FAA DRS - Entry in Federal Register Document (Docket FAA-2025-3432)
  • EASA – AD 2024-0236 ‘Engine Coolant Contamination – Inspection’ (TAE 125-02-125), effective 17.12.2024
  • Continental SB CG 125-1030 P1 (Rev. 4 & Rev. 6) – Coolant analysis/limit values

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