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On February 13, 2007, about 1700 Pacific standard time, a Columbia LC41-550FG, N194LF (known as a "Columbia 400") experienced a roll control system malfunction during cruise approximately 10 miles north-northeast of Banning, California. The airplane was not damaged during the incident. The private pilot, who was the sole occupant in the airplane, was not injured. The airplane was registered to Ridan Investments, Inc., Temecula, California, and was operated by the pilot-owner. Visual meteorological conditions prevailed at the time of the incident, and no flight plan had been filed. The business flight was performed under the provisions of 14 Code of Federal Regulations Part 91. The flight originated from Long View, Texas. Thereafter, the pilot made a couple of interim landings during the cross-country flight to the French Valley Airport, Murrieta, California, his home base.
The pilot reported to the National Transportation Safety Board investigator that after departing El Paso he climbed to 17,000 feet. While en route, the autopilot's annunciator light illuminated, and he heard an audible "check attitude" warning. The pilot turned off the autopilot. He then attempted to turn the yoke (control stick), but its movement felt restricted. The pilot stated that "it felt like the autopilot did not disengage."
To address the problem, the pilot cycled the autopilot off and on. He reported that the "yoke did not release right away," but after about 5 seconds he had full control of the airplane. The flight progressed without further incident, and the pilot landed at St. George, Utah.
Thereafter, the pilot departed and continued his planned flight toward the French Valley Airport. Initially, the autopilot seemed to function perfectly. However, when the pilot was cruising about 10 miles north-northeast of Banning, he again heard the "check attitude" warning.
The pilot reported to the Safety Board investigator that the airplane was in a standard turn at the time and its nose was level. The pilot responded to the alert by again disconnecting the autopilot. Then, he attempted to turn the airplane to the right to level the wings. The yoke turned to the right but its movement stopped at the center position. In the pilot's report to the Safety Board investigator, he stated that the yoke "would not turn past neutral" and he "could not get any right aileron control. The airplane continued rolling to the left...."
According to the pilot, he is not encumbered with any physical strength limitations. Despite his best efforts at applying right aileron roll control inputs (even using both hands), he was not able to move the control stick right of the neutral aileron (wings-level) position. The airplane reached an approximate 90-degree left bank angle before the pilot's application of full right rudder control inputs returned the airplane to level flight and he reacquired control of his airplane.
The pilot further described the anomaly by stating that "the yoke felt as if it were hitting something very solid." It felt like the yoke "was hitting a metallic stop." The pilot arrived at the French Valley airport without right aileron control (beyond the neutral position), and he attempted to land. After two landing approaches that terminated in go-arounds, the pilot successfully landed and taxied to his hangar.
While taxiing, the pilot tried to get the aileron to move freely upon application of stick pressure. Also, after he parked the airplane he tried to move the yoke with his hands. According to the pilot, when he moved the yoke to the right, it would stop at the neutral position.
The pilot reported the control system malfunction to the Columbia Aircraft Manufacturing Corporation, and to the Safety Board.
The Federal Aviation Administration (FAA) Part 23 certificated airplane was manufactured in June 2006. It was issued a standard utility category airworthiness certificate. At the time of the incident, the airplane's total time was between 213 and 214 hours.
TESTS AND RESEARCH
Under the direction of the Safety Board investigator, selected accessories and components from the airframe were examined by participants from the FAA Riverside, California, Flight Standards District Office, the FAA's Los Angeles and Seattle Aircraft Certification Offices, Columbia Aircraft, Bend, Oregon, and Garmin, Salem, Oregon.
In pertinent part, during the examination the airplane's aft belly access panel was removed to gain access to the autopilot roll servo. The bridal cable that mechanically connects the roll servo to the aileron crossover rod was disconnected to isolate the aileron control system from the autopilot servo.
The Garmin participants checked the electronic logs associated with the G1000 and the autopilot servo, and no evidence of any servo or autopilot malfunction was detected. Additional tests were performed pertinent to the functionality and operation of the G1000's system, and no anomalies were found that related to the pilot's reported incident.
The parties verified existence of the pilot's reported flight control system malfunction (aileron binding) during a visual and physical inspection of the airplane. When the ailerons were manipulated, a thumping noise was heard emanating from the general vicinity of the center of the right wing's trailing edge, where a linear bearing was located (about wing station 86.0). Use of a flexible borescope revealed the presence of foreign object debris (FOD) on the bottom of the inboard side of the linear bearing housing. The FOD appeared to be consistent with a substance used by the manufacturer in the wing bonding process. Additionally, while examining the linear bearing, it was noted that the aileron push-pull tube near the mouth of the linear bearing was slightly darkened, indicating rubbing between the control tube and the bearing. During the examination, when the control surfaces were manually manipulated, the ailerons moved freely in the direction of a left turn but would not move past the approximate neutral point when an attempt was made to move them in the direction of a right turn.
Manipulation of both the control sticks in the cockpit revealed a noticeable restriction that felt like a "detent" existed at roughly the neutral point in the aileron travel. Full aileron deflection was achieved in both directions using the control stick, but extra force was required to push the stick past the neural position "detent" when moving the stick from the left to the right.
Movement of the right aileron's push-pull control tube was found to be partially restricted in an area where it was routed through the right wing's linear bearing, although full control travel was still achieved in both directions during this examination, unlike in the pilot's reported experience. All remaining components of the aileron control system performed normally and according to type design, according to the Columbia participant.
According to 14 Code of Federal Regulations (CFR) Part 21.3, the type certificate holder shall report to the FAA any failure or flight control system malfunction, defect, or failure that causes an interference with normal control of the aircraft or that derogates the flying qualities. Previous reports relating to flight control malfunctions of the ailerons and elevator had been received by the manufacturer. No evidence was provided by Columbia indicating that it had followed up with these reports by notifying the FAA. Following this investigation, the manufacturer enhanced its internal reporting procedures.
Also, the manufacturer issued a Mandatory Service Bulletin (SB 07-002) to address identification and prevention of similar control binding events.
The FAA issued an Airworthiness Directive (2007-07-06) to address the incident. The AD was pertinent to Columbia Aircraft Manufacturing (previously The Lancair Company) airplane models LC40-550FG, LC41-550FG, and LC42-550FG. In the "Summary" portion of the AD, the FAA made the following statements: "This AD requires you to add information to the Limitations section of the Airplane Flight Manual (AFM). This AD also requires you to repetitively inspect the aileron and the elevator linear bearings and control rods for foreign object debris, scarring, or damage and take all necessary corrective actions. This AD results from reports of possible foreign object contamination of the linear bearings. We are issuing this AD to prevent jamming in the aileron and elevator control systems, which could result in failure. This failure could lead to loss of control."