Texas

The purpose of the flight was for the instructor-pilot to prepare the first and second pilots for their FAA Part 135 competency and proficiency checks scheduled to be conducted in the accident airplane the following week, with operator proving tests to follow shortly thereafter. The first pilot obtained a computer science corporation (CSC) direct user access terminal service (DUATS) weather briefing and filed an instrument flight rules (IFR) flight plan. The instructor-pilot was listed as the pilot-in-command. The airplane took off and proceeded to its designated practice area. According to the cockpit voice recorder (CVR), the pilots practiced various maneuvers under the direction of the instructor-pilot, including steep turns and approaches to stalls. Then the first pilot was asked the to demonstrate an approach-to-landing stall. The first pilot asked the instructor-pilot if he had "ever done stalls in the airplane?" The instructor-pilot replied, "It's been awhile." The first pilot remarked, "This is the first time I've probably done stalls in a jet. Nah, I take that back, I've done them in a (Lear)." The instructor pilot said he had stalled "the JetStar on a [FAR] one thirty five ride." Flaps were extended and the landing gear was lowered. Digital electronic engine control (DEEC) recorded a power reduction that remained at idle. According to national track analysis program (NTAP) data, the stall was initiated from an altitude of 5,000 feet. The stick shaker sounded and shortly thereafter, the recording ended. The consensus of 25 witness' observations was that the airplane was flying at low altitude and doing "erratic maneuvers." One witness said it "seemed to stop in midair," then pitched nose down. Some witnesses said that the airplane was spinning. Other witnesses said it was in a flat spin. Still another witness said the airplane fell "like a falling leaf." The airplane impacted marshy terrain in a nose-down, wings-level attitude. Wreckage examination revealed the landing gear was down and the flaps were set to 25 degrees. Both engines' compressor/turbine section blades were gouged and bent in the opposite direction of rotation, and there were rotational scoring marks on both cases. No discrepancies were noted.

The cargo flight was cleared for a visual approach to the 5,000-foot long, by 150-foot wide asphalt runway. Based on estimated landing weight of the aircraft, the Vref was estimated at 116 KIAS. Air traffic Control (ATC) radar data revealed that the flight maintained a ground speed above 190 knots on final approach, to include the touchdown zone for runway 13. The first evidence of braking was noted at a point 1,247 feet from the departure end of the runway. Braking signatures on the asphalt as well as off the pavement were consistent with an operational anti-skid system. Witnesses at the airport also observed the airplane flying very fast and touching down long. Both crewmembers, the 4,689-hour captain and the 2,873-hour first officer, were familiar with the airport, and the flight was 20 minutes ahead of its scheduled arrival time. The airplane overran the departure end of runway 13, impacted the airport perimeter fence, proceeded across a roadway, took out another fence, and collided with two trees in a cemetery. The airplane was found to be within weight and balance limits for all phases of the flight. The installed cockpit voice recorder (CVR) was found not to be functional.

During cruise flight, the 33,000-hour pilot stated that the airplane encountered "extreme clear air turbulence followed by three jolts in rapid succession." He "heard a loud pop as he jerked the throttle to the flight idle position." As the airspeed was slowing, the pilot attempted to add power. The "throttle would not move from the flight idle position and the propeller went into BETA." The airplane pitched downward as the pilot continued to try and "push the throttle lever forward." The airplane established "a rate of descent in excess of 10,000 feet per minute at a near vertical attitude." The pilot initiated an evacuation of the airplane and deployed his parachute (the pilot was wearing a sport parachute during the flight). Subsequently, the airplane impacted terrain. During a post accident examination, no mechanical anomalies were noted on the airframe, propeller, or engine that could have caused the accident. The reason for the loss of propeller pitch control could not be determined.

The aircraft overran the departure end of the runway while landing on Runway 33. The 5,200-hour pilot reported that while on the base leg, the annunciator light for the "low pitch stop" propeller system on the right side illuminated. The pilot pulled the circuit breaker and left it out, as per the pilot operating handbook (POH). During the landing-roll, the pilot encountered a severe yaw to the right. The pilot added power to the right engine and realigned the airplane down the centerline. He then applied brakes and reverse thrust. The pilot stated that " it felt like I had no braking action and then felt the right side grab and brake, but not the left." The combination of right side braking and the right low pitch system malfunction caused considerable adverse yaw, jerking the plane to the right. The pilot applied power again and straightened the nose of the airplane. He then made the decision to go around, but at this point did not have adequate airspeed or runway length to safely accomplish a go around. He applied the brakes again, and the airplane immediately yawed to the right again, at which time the pilot was unable to compensate before the airplane caught the edge of the runway. The airplane went into the grass, where the pilot attempted to control the direction of the airplane and bring it to a complete stop. Examination of the hydraulic brake hoses from the left and right main landing gears revealed that both hoses appeared to have been damaged with a hand tool.

The corporate jet was in a descent to attain a Mach 0.884 target speed during an airplane type certification flutter test. The airplane (a unique test bed) had a known speed-dependent tendency to roll right which was attributed to wing and aileron twist deviations. As the speed increased during the accident flight, the pilot had to apply full left aileron to be able to maintain airplane control. The airplane completed the test point about 30-degrees right-winglow, and subsequently began to roll to the right, "like a barrel roll...not real fast," that the pilot reported he could not stop. Although the manufacturer’s engineering analysis (which did not include any high-speed wind tunnel testing) predicted positive lateral stability up to Mach 0.90, lateral control was lost during the accident flight, and the airplane rolled about 7 times during a 49-second timeframe, from about 30,500 feet until a near-vertical ground impact. A review of telemetry data revealed that, just before the rolls began, the airplane's elevator moved to the 3.5 degrees trailing-edge-up (TEU) position, and the airplane's heading deviated right. Less than 1 second later, the rudder moved from 2 degrees trailing-edge-left (TEL), to 6.5 degrees TEL, and the combination of the TEU elevator and the left rudder input coincided with a marked increase in airplane's right deviation. Elevator-up deflection and rudder-left defection were maintained, with some variation in magnitude, to nearly the end of the data. Because the known speed-dependent tendency to roll right had created significant control problems on a previous flight, the ailerons were removed, modified and replaced, and a Gurney flap was added to the right wing. After the addition of the Gurney flap, the lateral trim margin improved to about 40 percent required (where 50 percent was neutral) up to 305 KCAS. It was then determined that flutter testing could continue to higher airspeeds if the pilot needed to apply a "small" wheel force to augment the trim. The pilot had been instructed to reduce airspeed if there was a problem during the flutter testing, and had done so during an uncommanded roll to the left on the previous flight. Telemetry data from the accident flight revealed that at initiation of the upset, the pilot attempted to level the wings and raise the nose, but the airplane continued to diverge from stable flight, and it continued to accelerate beyond the airplane’s demonstrated flight diving speed. It is undetermined if the pilot could have reduced the speed of the airplane in time, during the initiation of the upset, so that the airplane would not diverge. After the accident, the company conducted high-speed wind tunnel tests, and found that lateral stability decreased with increasing Mach and angle of attack (AOA). Lateral stability became negative (unstable) above Mach 0.83, and rudder input intended to augment lateral trim above a certain Mach could aggravate the situation. In addition, a TEU elevator input would increase AOA, and also result in deteriorated lateral stability. High speed wind tunnel data also revealed that roll authority deteriorated above Mach 0.86, and by Mach 0.88, the aileron upper and lower surfaces were both in separated flow regions. The follow-on flutter test airplane, which successfully completed the certification requirements, was equipped with vortex generators and thicker trailing-edge ailerons. It also did not require the external trim device needed on the accident airplane due to improvements in manufacturing.

The airplane impacted a dirt field and a power line following a loss of control during a simulated engine failure while on a Part 135 proficiency check flight. Both pilots were seriously injured and could not recall any details of the flight after the simulated engine failure. Witnesses observed the airplane flying on a westerly heading at an altitude of 100 to 200 feet, and descending. They heard the sound of an engine “surging” and observed the airplane’s wings bank left and right. The airplane continued to descend and impacted the ground and power lines before becoming inverted. A pilot-rated witness reported that he observed about ¼ inch of clear and rime ice on the airplane’s protected surfaces (deice boots) and about ½ inch of ice on the airplane’s unprotected surfaces. An NTSB performance study of the accident flight based on radar data indicated that the airplane entered a descent rate of 1,300 feet per minute (fpm) about 1,100 feet above the ground. This rate of descent was associated with a decrease in airspeed from 130 knots to 92 knots over a span of 30 seconds. The airplane’s rate of descent leveled off at the 1,300 fpm rate for 45 seconds before increasing to a 2,000 fpm descent rate. The true airspeed fluctuated between a low of 88 knots to 102 knots during the last 45 seconds of flight. According to the aircraft manufacturer, the clean, wing flaps up stall speed was 78 knots. However, after a light rime encounter, the Pilot’s Operating Handbook (POH) instructed pilots to maintain additional airspeed (10 to 20 KIAS) on approach “to compensate for the increased pre-stall buffet associated with ice on the unprotected areas and the increased weight.” With flaps up, a minimum approach speed of 105 KIAS was recommended. The POH also stated that a significantly higher airspeed should be maintained if ½ inch of clear ice had accumulated on the wings.

The twin-engine airplane impacted the ground during an uncontrolled descent while maneuvering in dark night instrument meteorological conditions in the vicinity of Lewisville, Texas. The commercial pilot contacted the approach controller and stated that his attitude indicator was "not helping" and needed "a little bit of help with trying to keep it straight." The pilot was instructed by approach control to maintain an altitude of 3,000 feet msl. The approach controller confirmed with the pilot that he could not fly headings, and instructed the pilot to turn right. Seconds afterwards, the pilot was instructed to turn left and the controller would tell him when to stop the turn. The pilot acknowledged. There were no further communications between the pilot and air traffic control. The airplane initially impacted in a near vertical attitude into a wooded area adjacent to a rural paved road, slid across the road, and impacted a residence. Radar data showed that the airplane's magnetic heading was erratic throughout the 5-minute flight. The gyro instruments found at the accident site were the copilot's direction gyro (vacuum), a turn and bank indicator (electric), and the pilot's attitude indicator (vacuum). The gyros were disassembled, and visually examined. The co-pilot's direction gyro examination revealed rotation signatures on the gyro and the gyro housing. The turn and bank indicator revealed a "faint" rotational signature on the gyro. The pilot's attitude indicator gyro had no rotational signatures, and exhibited blunt impressions corresponding to the gyro buckets on the inside of the gyro-housing wall. A maintenance repair data plate ("Functional Tested") was found on the attitude indicator's instrument housing dated 12/2/02. Due to the extent of the fire damage, no instrument readings could be obtained. Seven days prior to the accident flight, a company pilot who flew the accident airplane reported that the pilot's attitude indicator (part number 102-0041-04, serial number 92B0346) "rotated" and the flight was aborted. The next day, the attitude indicator was removed and bench checked, cleaned, and adjusted. The attitude indicator was reinstalled and an operational check on the ground was performed. Three days prior to the accident the pilot's attitude indicator was again removed for an overhaul. According to company maintenance personnel, the attitude indicator was reinstalled the night prior to the morning of the accident, and an operational check on the ground was performed. Radar data showed that the aircraft did not stabilize on a particular heading throughout the flight. Physical evidence showed that the pilot's attitude gyro was not "spooled" at the time of impact.

The crew was completing a local post maintenance test flight at Laredo Airport. After several touch-and-goes, the aircraft was in initial climb when the left engine lost power, followed shortly later by the right engine. The crew reduced his altitude and ditched the aircraft in the Casa Blanca Lake, about 50 feet from the shore. All three crew members were evacuated safely while the aircraft sank in six feet of water.

After a visual approach to the 3,975 foot long by 50-foot wide runway, the turbojet airplane touched down about 2,100 feet beyond the landing threshold, and overran the departure end of the runway. The 5,600 hour pilot in command (PIC) reported that the approach speed and descent rate were "normal," and the aircraft was on short final over the trees at the "desired speed." Once the trees were clear, the aircraft descended to the runway at idle power. During the descent the PIC noticed a 16-knot increase in speed above reference. The PIC elected to continue "because the aircraft was close to the runway" and the PIC thought he had "extra landing distance to work with beyond what was required." The PIC reported that the aircraft "floated beyond the desired touchdown point," and "at this point [the pilots were] committed to stopping the aircraft." Passing the last third of the runway, the aircraft turned to the right "without" input from the pilots, overran the departure end, and collided with trees. Once the aircraft left the runway, the PIC stowed the thrust reversers and attempted to shut down the engines. Due to the "violent ride," the PIC managed to shut down one engine. A post-impact fire consumed the aircraft after the crew assisted to evacuate the occupants. No mechanical or maintenance anomalies were discovered with the aircraft. According to the flight manual, based on 29.74 inches HG, 1,808 PA, 30 degrees Celsius, zero wind, and an aircraft landing weight of 14, 500 lbs, the calculated total stopping distance (air and ground distance) at reference speed (Vref), was estimated at 2,955 feet. According to the flight manual, the "total distance" is based on full flaps, speed brakes after touchdown, Vref at 50 feet over the runway threshold, idle thrust when crossing the threshold, and no thrust reverse.

The pilot arrived at Mexia-Limestone County Airport (TX06), Mexia, Texas, sometime before 1100. Once onboard the airplane, a witness, and an acquaintance of the pilot, closed and locked the airplane's cabin door for the pilot, and walked away from the airplane. He also reported that after the engines to the airplane were started, the airplane stayed on the ramp and idled for 10 to 15 minutes. No one saw the pilot taxi to the runway, but he taxied to the north end of Runway 18 for a downwind takeoff to the south. Examination of the accident site found the wreckage oriented along a path consistent with an extended centerline of runway 18. The airplane was found along a fence line approximately 1/4 mile from the departure end of Runway 18. The airplane's track was along a 183-degree bearing, and there was a large burn area prior to and around the debris zone along the wreckage path. Examination of the cockpit revealed a 9/16-inch hex-head bolt inserted in the control lock pinhole for the control column. Under normal procedures Cockpit Check in the Duke 60 Airplane Flight Manual, for Preflight Inspection the first item listed is: 1. "Control Locks - REMOVE and STOW". In addition, under normal procedures Before Starting checklist in the Duke 60 Airplane Flight Manual, the fourth item to check is listed as: 4. "Flight Controls - FREEDOM OF MOVEMENT and PROPER RESPONSE"