The FAA recently issued a Special Airworthiness Information Bulletin (SAIB) that warns operators and maintainers about safety hazards associated with quarter-turn engine cowl fasteners on Textron Aviation-manufactured jets. This list includes Cessna Citations, Beechjet 400A/XPs, and Hawkers. However, the FAA said, the airworthiness concern is not considered an unsafe condition that would warrant issuing an airworthiness directive.
According to the FAA, there have been several incidents of engine cowl damage and resulting separations in Textron turbofan airplanes believed to be primarily caused by maintenance error. These separation incidents resulted in damage to the airplanes, and some incidents have “marginally affected” airplane handling capabilities.
“The Textron turbofan-powered fleet uses quarter-turn fasteners to assemble the engine cowl system,” the FAA noted. “Failure to verify engagement of all quarter-turn fasteners can lead to cowl door damage and/or separation due to the aerodynamic loads. Cowl doors that separate from the airplane may strike empennage components, causing structural damage and potential loss of airplane control.”
Thus, the FAA issued this SAIB to advise of the safety hazards and potential dangers of inadequate and infrequent preflight inspections of the quarter-turn fasteners used to attach engine cowling system components. It also called for routine preventive maintenance to identify improperly seated or improperly latched quarter-turn fasteners or cowl doors with excessive forward edge gaps, cracks, or contour anomalies.