MD-83
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors; Aircraft; Procedure
The airplane came in from another airport and we had a short 40 minute turn with crew change. After the airplane was chocked at the gate I signaled the incoming Captain that I would be doing my exterior preflight right away. I completed my exterior preflight before ATS was able to service the airplane. The standard service included LAV-service front and aft. We pushed off the gate on schedule and landed without incident. During my exterior preflight check I noticed ice build-up at the forward LAV service panel. The ice build-up was thick enough for the quick-fasteners to jam. I had to knock the ice off in order to open the panel. Under the panel I saw a rag or paper-towels of some sort sticking out of the service- fitting. I realized that the rag was preventing the service-fitting from properly sealing the drain-pipe and LAV fluid was able to leak out continuously throughout the previous flight causing the icing-over of the panel. The icing did not stop there. As the fluid leaked out aerodynamic forces in flight pushed it along the fuselage causing icing on the instrument venturi exhaust as well. That by itself would not be a big issue; but a couple feet downstream from the venturi exhaust were the static ports for the cabin emergency relief valves. Had more fluid leaked out than it could have been entirely possible for the static ports to ice over as well....rendering the emergency relief valves inoperative. That could have ruined our day! I ordered our ground-handler to remove the object from the forward Lav service fitting. The rest of the flight was uneventful. ATS should take whatever time is necessary to service the airplane properly. Rushing things creates links in the accident chain. In this case nothing happened; but that is not always the case. Crews do not have the time to supervise the servicing of the airplane on a 40 minute turn with crew-change.
MD83 Captain reports discovering a leaking lav service drain during a turn around preflight causing ice to form on the belly of the aircraft flowing back to the instrument venturi exhaust.  The ice stopped short of the static ports for the cabin emergency relief valves just down stream.