Where is the most corrosive environment in any business aircraft? The Landing Gear wells? Fuel Tanks? Tailcone? No, It’s the Lavatory, particularly in Citation aircraft. The Importance of looking for corrosion in all Citation Airframes under the Lavatory Installation is paramount.

West Star Aviation has seen several instances on customers’ aircraft where an inadvertent spill in the past has created a sizable problem to deal with in the present. The repairs range from a simple cleaning and treating of an affected area, to aircraft outer skin and stringer replacement.

The spills are a problem because of where the overflow puddle can propagate. In the lowest point in the belly of all older legacy Citation Aircraft (500’s, 550, 560’s ), sits the Aileron bellcrank for the wing-to fuselage cables. This is where the blue water spill puddle will form. Obviously, this puddle is very corrosive to aluminum surfaces, and the fluid will attack and corrode untreated rivets, stringers and skins. This can cause skin changes, DER Repair work, stringer re-sectioning and the like. There have been several Service Bulletins and ADs issued to address the problem, (AD2008-03-10), but nothing works as well as being forever vigilant with inspecting this area, and of course, timely cleanup of inadvertent spillage.

We at West Star Aviation, have often discovered a number of areas damaged due to inadvertent lav spillage. We have replaced skins, stringers etc. and other repairs involving DER drawings and approval. The repair scheme can be quite involved at times, and be very labor intensive to remedy, so keeping the area clean of spills and frequent inspection can help minimize the chance that this corrosion can become
a major problem.