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Citation Blue Water Corrosion Prevention

September 2009

All aircraft have unique hotspots for corrosion; Citations are no exception. This article addresses blue water corrosion concerns for Citation models 500, 550 & 560.


A corrosion hotspot for Citation 500s, 550s and 560s is around and under the toilet assembly. For most, this assembly is mounted in the aft cabin. The toilet chemical used (blue water) is highly corrosive, especially to the aluminum structure below the toilet. Great care must be taken to prevent a blue water spill. If a spill occurs, it must be cleaned up immediately to prevent potential corrosion issues in the future. Any spill left unattended, no matter how small, can make its way down to the structure below where the aileron sector attaches and cause serious damage and costly repairs.


Due to the potential for serious corrosion, it is a requirement for this area to be inspected once a year via the Phase 18. Every three years or 1200 hours, this area is also included in the under-floor inspection required on the Phase 5. Because not all areas susceptible to corrosion can be seen visually with a flashlight and mirror, a borescope must also be used during inspection. If corrosion is found in this area, consult the appropriate maintenance manual for the required course of action.