A CE560XL rudder system seized inflight because the tail cone seep hole was blocked or too small and previously accumulated water froze. All preflight flight control checks were normal.
Synopsis
A CE560XL rudder system seized inflight because the tail cone seep hole was blocked or too small and previously accumulated water froze. All preflight flight control checks were normal.
Narrative
The aircraft was parked over night under the canopy with the wind predominately at the tail and still in position the next morning. Upon arrival at FBO; it was blowing rain with 22 KTS; gusting to approximately 32-36 from 140 degrees. We had the aircraft turned more into the wind for start. ATIS at initial flight preparation was 150/22G32 2 1/2SM RA 40 OVC 14/10 29.78. ATIS at departure time was 170/23G36 2 1/2SM BR 004OVC 15/10. The preflight was in accordance with the checklist and had no abnormalities. It included the 'hell hole' and was normal. The gust lock was engaged and disconnected prior to moving the aircraft and engaged again after moving the aircraft. It was released again prior to engine start. After engine start; the control check and rudder bias check were normal. The rudder bias check was accomplished in the chocks prior to taxi. During taxi out; we made one 45 degree and five 90 degree turns and all were normal. We were initially cleared to 2;000 FT and then stepped to 6;000 FT. All that time was in the clouds with light to moderate precipitation; never more than dark green on the RADAR until about 6;000 FT where we transited a yellow band that the RADAR and Departure Controller verified was less than 4 miles thick. Step climbs to 10;000 FT until approximately 25 miles west with the RAT greater than 12 degrees. Anti-Ice was used out of 12;000 FT with the RAT 11 degrees and terminated approximately 14;000 FT with clear skies and 10 degrees. Remainder of flight was in the clear and uneventful. Descent into the clouds occurred again around 8;000 FT until approximately 1;600 FT. Arrival ATIS was 240/18G2g 6SM -SN 018 BKN 028OVC -2/-6 29.84; ILS 25. Autopilot was disconnected at approximately 2;500 FT MSL and Yaw Dampner at 600 FT AGL. There were no indications prior to or at that time that the rudder was abnormal. In the landing flare; while trying to align the nose approximately 5 degrees with the centerline; I noticed that I could not move the nose more than a degree or two. The rudder pedals were hard as if the Yaw Dampner or Rudder Bias was working against me. I actuated the Autopilot Disconnect Button 3 times in rapid succession in case the Yaw Dampner was still connected. No effect. As we were in the flare; I elected to not say anything until the aircraft was on the ground. As the aircraft slowed on the runway; I informed the SIC that I felt that I could not move the rudder pedals but I had control through differential braking. I elected to make the turnoff at about 6;000 FT down the runway and at 10 KTS as I had full control of the aircraft and steering through differential braking. I stated my intention to taxi to parking and explained fully the problem. We agreed to the plan and I transferred aircraft control while on the parallel taxiway so that the First Officer could evaluate the situation. Taxi and shutdown was uneventful. Upon shutdown; without engine bleed air; I again attempted to move the rudder pedals and could not. After taking care of our passengers; I reset and released the Control Lock. It had no effect. I attempted to move the rudder manually and it would not move. I have several suggestions. Inspect the weep hole in the XL and XLS fleet for proper size and ability to drain. Find the source of the water entering the tail cone. Instruct crews in potential for freezing in tail cone. Emphasize need to tap tail cone for indications of ice or water lying in bottom. Suggest crews manually move rudder. This may not be possible due to height off ground of rudder. Add simulator training in jammed rudder and jammed elevator landing techniques. Manufacturer: Increase size of weep hole. Find the source of the water entering the tail cone. Dispatch: Increase fuel loads to 45 minutes extra (minimum) to allow the crew to hold in order to sort out a problem like this or to divert to a suitable runway. Had we been dispatched with little extra fuel and the winds not been down the runway; we could have lost the aircraft.
Second reporter narrative
After clearing the runway; the After Landing checklist was completed; and the pilot flying told me we had a rudder control problem. He then transfered the controls to me for a minute to get my input. The rudders were basically locked; we still had control enough to taxi safely to the ramp where we deplaned our passenger. As a side note; all preflight items including checking the 'hell hole' and rudder bias were completed. A thorough post flight was also completed; then the company notified. We were told that the drain hole in the tailcone was too small; and that enough water had built up and at cruise had frozen to the point of blocking the rudder cable and pulley.
NASA callback
The Reporter stated that no inspection method is published for pilots to check for water accumulations in the tail section. Maintenance stated that the water probably entered the tail cone through the elevator hinges and because of water surface tension did not exit through he drain hole which Cessna states must be 0.201' in diameter. The ice in this aircraft was identified over an hour after landing when the aircraft was towed to the hanger and the tail cone removed. The tail cone is 'V' shaped and the ice was approximately one foot deep and 4-6 inches wide where it encased the rudder cables. If more water has accumulated the elevator cables could also have been encased in ice. The Reporter has flown several other light twin jet types and suspects that other aircraft have the same issue because of drain hole design. He knows of one other instance in this aircraft type where ice has affected the rudder system. A serious concern for this Pilot was also the lack of reserve fuel had this anomaly occurred on landing at an airport with cross winds such that a landing was no possible. He suggests increasing the amount of contingency fuel for operations into airports with adverse weather.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.