AD/CON/86 - ECI Cylinder Assemblies

This Airworthiness Directive requires owners/operators of Teledyne Continental Motors 520 and 550 series engines fitted with ECi cylinder assemblies P/N AEC631397 (and certain RAM‑modified TSIO‑520 variants) to check cylinder serial numbers and, for serials 1044–7708, follow FAA AD 2004‑08‑10 to determine and perform required cylinder replacements. It aims to prevent loss of engine power from cracked or separated cylinder heads; compliance must occur within 50 flight hours or one month, or before further flight when replacement is mandatory. Owners pay for inspections and replacements; the regulator enforces compliance.