Test

After takeoff for a maintenance check flight, both engines on the twin-engine airplane experienced a loss of engine power. The 7,200-hour pilot had recently purchased the airplane, which had not been flown for nearly four years. The pilot, who is also a certificated airframe and powerplant mechanic, completed the inspection of the airplane prior to takeoff. During the engine run-up, the pilot noticed that the RPM and manifold pressure on the left engine did not correspond with those of the right engine. During the takeoff roll, the pilot believed the RPM on both engines began to rise to near acceptable levels, but not entirely. However, he did not abort the takeoff. The airplane became airborne for a short time, and then began to descend into trees before impacting the ground. The reason for the reported loss of engine power could not be determined.

The 9,500-hour ATP-rated pilot was forced to secure the left engine during a maintenance test flight following the malfunction of the left propeller. The crew executed single-engine instrument landing system (ILS) approach to runway 13. During short final, the crew noticed that the alternator light was illuminated and the hydraulic pressure gauge indicated "0" pressure. The landing gear was already extended and the flaps were partially extended, so the crew elected to continue the approach to a full-stop landing. Upon landing, the pilot immediately turned on the direct current (DC) hydraulic pump. The pilot added that he then realized that he was unable to maintain directional control of the airplane due to the lack of nose wheel steering and the ineffective wheel brakes. As a result, the airplane continued to veer to the right and exited the runway. The airplane collided with the airport perimeter fence and continued down into a drainage ditch. The examination of the aircraft revealed that the hydraulic pump switch did not appear as if it had been turned on.

The purpose of the flight was to "check out" the airplane before delivering it to its new owner, and to provide the copilot with an indoctrination ride in the Cessna 414. During the approach, the pilot provided guidance and corrections to the copilot. The copilot flew the airplane to within 200 feet of the ground when the nose of the airplane yawed abruptly to the right. The pilot took control of the airplane, and pushed the engine and propeller controls to the full forward position. He placed the fuel pump switches to the "high" position, retracted the flaps, and attempted to retract the landing gear. With full left rudder and full left aileron applied, he could neither maintain directional control nor stop a roll to the right. The airplane struck the ground and continued into the parking area where it struck an airplane and a waste-oil tank. Examination of the airplane following the accident revealed that the landing gear was down and locked, and the propeller on the right engine was not feathered. The emergency procedure for an engine inoperative go-around required landing gear retraction and a feathered propeller on the inoperative engine. The pilot's handbook further stated, "Climb or continued level flight is improbable with the landing gear extended and the propeller windmilling." After the accident, both pilots stated that they didn't notice a power loss on the right engine until the copilot surrendered the flight controls. The right engine was removed and placed in a test cell. The engine started immediately on the first attempt and ran continuously without interruption.

The aircraft was engaged in a local post maintenance test flight at Fort-de-France-Le Lamentin Airport, carrying five technicians and three crew members on behalf of the Escadron de Transport Outremer 58. After engine startup, the crew started to taxi when a fire erupted. The aircraft was stopped on the ramp and all eight occupants escaped uninjured. Within three minutes, fire bombers were on site and extinguished the fire. Nevertheless, the aircraft was damaged beyond repair.

The aircraft departed Papeete-Faaa on a local post maintenance flight with one engineer and one pilot on board. Shortly after takeoff, while in initial climb, the pilot informed ATC about control problems and elected to return. Unable to maintain control, he decided to ditch the aircraft few hundred metres offshore. The aircraft sank by a depth of 21 metres and both occupants were able to swim to shore.

The crew departed Pyongtaek-Desiderio AAF on a local test flight. The goal of the flight was to test the aircraft after replacement stall strips had been fitted to the outer edge of the wings. In flight, the crew lost control of the airplane that entered a dive and crashed in a field, bursting into flames. Both occupants were killed.

The four engine aircraft departed Tehran-Mehrabad Airport at 1225LT on a local test flight. About 35 minutes into the flight, the crew informed ATC about a double engine failure when control was lost. The aircraft crashed in 'Rudshur', near the Shur River. All seven occupants were killed.

The aircraft was subject to major maintenance during the last two months, especially with the rudder actuators that were replaced. As there were still problems with the actuators during the last flight, decision was taken to make the appropriate adjustments followed by a flight to Salekhard. During the takeoff roll on runway 16/34, at a speed of 150 km/h, the aircraft deviated to the left and the captain decided to counter this deviation by using the nosewheel steering system. This caused the right front tyre to burst. At a speed of 250 km/h, the takeoff procedure was abandoned but this decision was taken too late. Unable to stop within the remaining distance (the runway 16/34 is 2,530 metres long), the aircraft overran, lost its nose gear and rolled for 577 metres before coming to rest. All 11 occupants escaped uninjured while the aircraft was damaged beyond repair.

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 aircraft departed Chofu Aerodrome at 10:26 (JST) with the captain and a mechanic on board for a company test flight prior to an airworthiness certification inspection. During the flight at around 10:52, the aircraft crashed into woods at Nishine, Kamiose, Ogawa, Naka County, Ibaraki Prefecture. The two persons on board the aircraft, the captain and the mechanic, both sustained fatal injuries. A fire broke out and the aircraft was destroyed.