N709CA

On May 8, 2002, about 1100 eastern daylight time, a Bombardier CL600-2B19 regional jet (CRJ), N709CA, hull number 7238, operating as Comair flight 5883, experienced aileron control stiffness during cruise flight, after departing Cincinnati/Northern Kentucky International Airport (CVG), Covington, Kentucky. The captain, first officer, flight attendant and 15 passengers were not injured. The flight was operating on an instrument flight rules flight plan to Eppley Airfield (OMA), Omaha, Nebraska. The scheduled passenger flight was conducted under 14 CFR Part 121.

According to the company's irregular operations report, the airplane was pushed back during a period of moderate to heavy rain. After pushback, the airplane was held on the taxiway for about 30 minutes while the rain continued. Takeoff, about 1030, also occurred during a period of heavy rain.

After leveling off at flight level 280, while in cruise flight, the "AP TRIM IS LWD" caution annunciator illuminated. The first officer disconnected the autopilot, and found the aileron controls to be "stiff and binding." The captain then took control of the airplane, and also found the aileron controls to be stiff and binding. The captain applied "light to moderate" roll input and felt a snap. Aileron control then operated normally.

The captain executed left and right turns with no additional problems or binding noted. The crew re-engaged the autopilot, and the flight continued to an uneventful landing.

On the same date, about the same time, a second CRJ, N937CA, hull number 7044, operating as Comair flight 5296, also experienced aileron control stiffness after departing Cincinnati/Northern Kentucky International Airport. The captain, first officer, flight attendant and 38 passengers were not injured. The flight was operating on an instrument flight rules flight plan to Will Rogers World Airport (OKC), Oklahoma City, Oklahoma. The scheduled passenger flight was conducted under 14 CFR Part 121.

According to the company's director of corporate safety, the flight had also departed about the same time as flight 5883. As reported in the company's irregular operations report, the airplane was climbing from flight level 290 to flight level 310, when the "autopilot RWD trim" caution annunciator illuminated. The crew completed the appropriate quick reference handbook (QRH) procedures, but 1 to 2 minutes later, the autopilot RWD trim caution annunciator again illuminated. The first officer disconnected the autopilot and felt he had jammed aileron controls. The captain then attempted fly from his side and also found the ailerons jammed. The crew completed the QRH jammed-aileron procedures, and diverted to Lambert-St. Louis International Airport (STL), St. Louis, Missouri.

About 1330, a third CRJ, N977CA, operating as Comair flight 5261, hull number 7157, also experienced aileron control stiffness while in cruise flight, after departing Cincinnati/Northern Kentucky International Airport about 1245. The captain, first officer, flight attendant and 17 passengers were not injured. The flight was operating on an instrument flight rules flight plan to Lehigh Valley International Airport (ABE), Allentown, Pennsylvania. The scheduled passenger flight was conducted under 14 CFR Part 121.

According to the company's irregular operations report, the LWD caution annunciator illuminated while the airplane was in cruise at flight level 290. The captain, who was the non-flying pilot, went through the pertinent QRH procedures and disconnected the autopilot. The autopilot was re-engaged, and the LWD caution annunciator again illuminated. The autopilot was again disconnected, "and the crew attempted to move the ailerons to no avail." The controls were not split. The captain contacted the company's maintenance control personnel, and was advised that his was the third similar event of the day and to descend to a lower altitude. The crew descended the airplane to 15,000 feet and felt the ailerons slowly loosen. The crew declared an emergency and landed without further incident at Lehigh Valley.

Weather, recorded at Cincinnati/Northern Kentucky International Airport at 1038, included heavy rain and mist. The weather, recorded at 1251, did not include rain; however, according to Comair's director of corporate safety, the airplane taxied through standing water prior to takeoff.

On June 6, 2000, a CRJ, N952C, hull number 7017, also experienced aileron control stiffness, which was documented as Safety Board occurrence number NYC00SA153. At the time, older CRJs, including hull number 7017, did not have main landing gear wheel bay splash shields installed. As a result of the investigation, Transport Canada and the Federal Aviation Administration (FAA) issued airworthiness directives (ADs) to require CRJ hull numbers 7003 through 7323 have the splash shields installed.

The incident airplanes were in compliance with the existing ADs.

On May 29, 2002, a meeting, facilitated by the Safety Board, was held at Comair facilities in Cincinnati, Ohio. Attendees included representatives from Bombardier Aerospace (BA), Transport Canada (TC), the Canadian Transportation Safety Board (TSB), the Federal Aviation Administration (FAA), the Airline Pilots Association (ALPA), and CRJ operators.

Discussions at the meeting included history, benchmarking, and preliminary recommendations. BA reported that approximately 600 CRJs had been delivered, with 68 per cent in North America. To that date, BA had been notified of 29 control stiffness cases, with 27 occurring while airborne. Four cases in Europe involved anti-icing residue.

The earlier ADs to install splash shields in the main wheel bays of older airplanes had been effective "until recently." Shields had been designed to allow a 0.040 inch gap between it and a composite wheel bin ("bathtub") in each wheel well. Incident airplanes were found to have much larger gaps, up to 0.20 inch.

Immediately behind the wheel bin, about 3 feet inboard the ice guard, was the aileron quadrant assembly. There were four bearings within the assembly, one of which, BA personnel determined to be more susceptible to freezing when saturated with water. As an interim measure, BA recommended lubricating the bearings, which the operators felt was beyond their maintenance capability since it would require maintenance personnel to disassemble, then reassemble and re-rig the assembly.

One of the operators recommended, and had produced a new splash guard model that also added a pliable seal on the side of the wheel bin, which BA agreed to evaluate.

BA also recommended interim flight procedures to exercise the bearings via the flight controls (the bearing moved less than 1/2 degree, 75 percent of the time) every 5,000 feet during climbs that involved precipitation, which was agreed to by the operators and ALPA; however, they wanted flight testing to determine how much pilot action was required for passenger comfort and concerns.

BA also announced a long-term fix to redesign the quadrant assembly.

After the meeting, the operators examined and corrected splash guard-wheel bin gaps, and Comair conducted misting and freezing experiments which resulted in a vertical and horizontal pulley freezing to each other, and determined that water splashed onto the ceiling of the wheel well would likely drip onto the pulleys.

On June 12, 2002, the ALPA representative suggested that a CRJ be equipped with wheel well cameras to taxi through and take off from water-contaminated runways to validate water flow. That recommendation was passed to BA by the Safety Board; however, BA was not able to flight test until August 29, 2002, and September 12, 2002.

On August 9, 2002, BA issued CRJ Temporary Revision (TR) RJ/109-2, effective for airplanes that had accumulated in excess of 5,000 hours of operation. The TR required that after an airplane departed a wet or contaminated runway, and had climbed to 10,000 feet mean sea level or when the temperature reached 32 degrees Fahrenheit, whichever occurred later, the ailerons had to be operated every 5,000 feet until the top of the climb. It also required in the Airplane Flight Manual, Emergency Procedures Section, that if frozen ailerons were suspected after departing a wet or contaminated runway, sufficient force must be applied on the affected side to free the jam. If unable to free the jam, descend into warmer temperatures. If still unable to free the jam, land at the nearest suitable airport, selecting the longest runway available with the minimum turbulence and crosswind.

On August 16, 2002, TC issued Canadian AD CF-2002-35R1, which made TR RJ/109-2 mandatory for continued airworthiness in Canada.

On September 16, 2002, the FAA issued AD 2002-19-07, effective October 10, 2002, which also required the utilization of TR RJ/109-2 for continued airworthiness in the United States.

On September 17, 2002, a second meeting was held at Comair facilities, with the same parties in attendance. BA reported, that since the previous meeting, there had been five additional control stiffness reports with three of those occurring in North America and two occurring in Europe. All occurred in heavy rain and/or standing water, and all were confirmed in climb or cruise. During four of the five events, the autopilot trim LWD/RWD EICAS was illuminated.

BA also reported the results of two flight tests, and provided a main landing gear bay video that revealed some ingestion of water, but very little dripping on the control cables and pulleys. Flight test data was still being evaluated.

BA had also conducted destructive bearing analysis of aileron aft control quadrants that had been removed from service. In the examinations, seals were found lifted in local areas, and there was the presence of contaminants in the bearings, some corrosion on inner races, and some bearings were not installed per drawing...