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On March 6, 2008, about 1630 eastern standard time, a Rockwell International 112TCA, N4623W, was substantially damaged when it overran runway 27 during an aborted takeoff from Brandywine Airport (OQN), West Chester, Pennsylvania. The pilot/owner, the sole person on board, was not injured. The flight was being operated under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed.
According to the pilot, on the morning of the day of the accident, he flew the airplane to OQN for maintenance on the airplane's weather data-link avionics. The pilot also requested that the maintenance facility address a residual autopilot issue from an August 2007 avionics upgrade by the same facility. The pilot stated that the airplane was released to him about 1600 on the day of the accident.
According to maintenance records and a technician's written statement, the autopilot electrical connector for glideslope coupling had been incorrectly "paralleled at the altitude transducer." The technician rewired the assembly to match the avionics manufacturer's cable assembly drawing. He conducted several functional checks, and confirmed that the system was wired and operated correctly. Subsequent to these checks, the technician instructed the pilot to "check his trim before he left as it runs during ground checks."
According to the pilot, prior to engine start, he noticed that the pitch trim was near its full airplane nose down (AND) position. He manually adjusted the trim to the takeoff setting. The pilot estimated that the airplane had a total of 37 gallons of fuel on board, and that the wind was "light and variable" at the time of the attempted takeoff. He conducted a normal engine start, and taxied to the runway. He reported that the engine runup was normal.
The pilot stated that he ensured that the autopilot was off, and that the "trim master breaker" switch was on, which was the manufacturer's recommended configuration for takeoff. The trailing edge flaps were in the retracted position, which was the recommended takeoff setting. The pilot initiated a full-length takeoff by advancing the throttle, and then releasing the brakes once he observed an indication of 30 inches on the manifold pressure (MP) gauge. At an indicated airspeed of approximately 65 knots and with approximately 40 inches MP, the pilot exerted aft pressure on the control column to lift off, but the airplane did "not feel right." The pilot reported that by the time the airspeed was approximately 75 knots, he had moved the column significantly aft, but the pitch attitude only increased slightly, and the airplane did not become airborne. The pilot then rejected the takeoff by retarding the throttle and applying the brakes. The airplane overran the runway at a speed that the pilot estimated to be between 20 and 30 knots. The airplane traveled down an embankment, and came to rest approximately 150 feet from the runway end, in a shallow ditch adjacent to a road. The pilot was uninjured, and there was no fire.
A witness stated that he pulled the accident airplane out of the maintenance hangar about 1630, and that the pilot returned on foot to the maintenance facility to report the accident about 1640.
The pilot held a private pilot certificate with airplane single-engine land rating, and he had approximately 130 total hours of flight experience. He had approximately 85 total hours experience in the accident airplane. Federal Aviation Administration (FAA) records indicate that the airplane was first registered to the pilot in September 2006. His most recent third-class FAA medical certificate was issued in August, 2007.
The airplane was manufactured in 1977. According to the maintenance records, at the time of the accident, the airplane had accumulated a total time in service of approximately 2,052 hours. The most recent annual inspection was accomplished in May 2006, and the airplane had accumulated approximately 39 hours since the annual inspection. The airplane was equipped with a Century III two-axis (pitch and roll) autopilot. The most recent maintenance activity was accomplished on the day of the accident.
The 1654 weather observation at an airport located approximately 14 miles north of the accident airport recorded winds from 270 degrees at 4 knots, clear skies, temperature 10 degrees C, dew point minus 2 degrees C, and altimeter setting of 30.18 inches of mercury.
According to FAA information, the asphalt runway measured 3,347 feet by 50 feet. Photographs indicate that the departure end of runway 27 terminated in a down-sloping embankment approximately 30 feet high, with a slope of approximately 45 degrees. The pilot reported that the runway surface was dry at the time of the event.
WRECKAGE AND IMPACT INFORMATION
Inspectors from the FAA arrived on scene approximately 2 hours after the accident. They reported that the propeller, engine cowling, left wing, and nose and left main landing gear incurred impact damage. The inspectors also reported that the pitch trim cockpit indicator and elevator trim tab were both in their respective full AND positions. A tire skid mark began at the painted runway number and continued to the end the pavement, a distance of approximately 375 feet. The next ground scars were three furrows in the grassy overrun beyond the end of the embankment. The furrows were located approximately 100 feet beyond the runway end, and the lateral spacing of the furrows was consistent with the lateral spacing of the accident airplane's landing gear.
Manufacturer's Normal Procedures Checklist
A binder containing the manufacturer's "Normal Procedures Checklist" for preflight and takeoff was recovered from the accident airplane. The registration number of the airplane was written on the cover of the binder. The checklist contained two separate entries to turn the master switch on, but it did not contain any corresponding entry between the two "on" entries to turn it off.
The same checklist contained three separate entries concerning the elevator trim setting. Item 9 in the "INTERIOR" section of the "PRE-FLIGHT INSPECTION" portion was "Elevator Trim Tab - NEUTRAL." Item 17 in the "EXTERIOR" section of the "PRE-FLIGHT INSPECTION" portion was "Elevator Trim Tab -CHECK." Item 5 in the "BEFORE TAKEOFF" section was "Elevator Trim Tab - TAKEOFF RANGE."
There were no explicit references to the autopilot in the checklist, but it did contain two implicit references. Item 4 in the "BEFORE STARTING ENGINE" checklist was "Avionics Master Switch - OFF," and item 14 in the "BEFORE TAKEOFF" checklist was "Instruments and Radios - SET."
A double-sided laminated checklist was recovered from the accident airplane, but it did not contain any annotations concerning its applicability to any aircraft type, model, or registration number. This checklist was similar to the manufacturer's checklist described previously. There were no explicit checklist references to the autopilot, but like the manufacturer's checklist, it contained two implicit references. Item 4 in the "BEFORE STARTING ENGINE" checklist was "Avionics Master Switch - OFF," and item 14 in the "BEFORE TAKEOFF" checklist was "Instruments and Radios - SET."
The only entry in the checklist that concerned elevator trim was item 5 in the "BEFORE TAKEOFF" section, which stated "Elevator Trim Tab - TAKEOFF RANGE."
Pilot's Operating Handbook for Autopilot
The manufacturer of the autopilot, Century Flight Systems, developed and provided a 36-page Pilot's Operating Handbook (POH) for the autopilot model that was installed in the accident airplane. The POH contained a "Pilot's Preflight Procedure," which consisted of 13 detailed steps and 6 "Notes." The "Notes" were printed in boldface font. The fourth "Note" stated "If autopilot ground check is prolonged, automatic trim may run to up or down limit..." The final step in the procedure was "Be sure all autopilot controls are off, that trim circuit breaker is reset, and that elevator trim is set prior to takeoff." This POH was not among the documents recovered from the accident airplane.
Airplane Examination and Testing by FAA
Post-accident examination and testing of the airplane elevator and pitch trim system by the FAA inspector yielded the following results: Elevator and manual pitch trim control continuity were confirmed, and the controls were observed to be functional and directionally correct. The electric pitch trim and cockpit pitch trim indicator were also observed to be functional and directionally correct.
The autopilot ON/OFF switch was spring-loaded to the OFF position. The switch was held in the ON position by an electric solenoid, which was only energized when the airplane avionics master switch was in the ON position, and electrical power was available on the airplane. When electrical power was removed from the autopilot, the solenoid released, and the autopilot switch returned to the OFF position. When electrical power was re-applied to the autopilot, the autopilot switch remained in the OFF position, unless it was manually repositioned to the ON position.
A test of the autopilot interaction with the pitch trim was conducted to determine the system response during pre-start and ground operation. With airplane electrical power off, the pitch trim was set to the takeoff position using the manual trim wheel. Electrical power was then provided to the airplane, and the avionics master switch was placed in the ON position. No motion of the trim wheel, trim indicator or trim tab was observed. The autopilot switch was then moved to the ON position. The pitch trim wheel rotated, and the trim wheel, trim indicator, and trim tab all moved to their full AND positions. When the autopilot switch was moved to the OFF position, the pitch trim components remained in their full AND positions.