Test

The crew was engaged in a test flight when the seaplane crashed in unknown circumstances off Miami. A crewmen was killed.

The crew was performing a test flight on this second production series. 45 minutes after departure, the crew informed ground about oil pressure problem on the left engine that was feathered. On a single engine approach to RAF Hucclecote, while at a height of 100 feet in marginal weather conditions (rain falls and gusty winds), the aircraft went out of control and crashed in flames. All four crew members were killed.
Source: http://aviation-safety.net/wikibase/wiki.php?id=141412

Crashed eight minutes after its take off from Homestead AFB while on a test flight. During initial climb, the left engine caught fire and exploded. A passenger was able to bail out while the rest of crew attempted to return to the airbase for an emergency landing. Few seconds later, the aircraft exploded, dove into the ground and crashed in flames in a field located near the airport. All four occupants were killed.
Crew:
Cpt Hewitt F. Mitchell,
2nd Lt Banford L. Russell,
Pvt Harry Luberoff.

The aircraft left RAF Ashbourne for a short test flight with one pilot and two passengers on board. En route, while cruising at a very low height, the twin engine aircraft hit power cables and crashed onto a small hill. All three occupants were killed.
Crew (42nd OTU):
F/O Archibald Douglas Vincent Forsyth, pilot.
Passengers:
Cpl Harry Garnet Sylvester,
LAC Harry Charles Halestrap.

The crew was engaged in a test flight after one of the engine was changed. Shortly after takeoff, while in initial climb, both engines flamed out simultaneously. The captain decided to return for an emergency landing but the aircraft lost height, hit the roofs of two wooded houses and crashed few km from the airport. A crew member was killed while four other occupants were seriously injured. The aircraft was destroyed.

After take off from Louisville Airport, while climbing, the aircraft (a CW-27 model) went out of control and crashed in a field located in Okolona, southeast of the airport. The aircraft was destroyed and all three crew members were killed. They were performing a test flight when the tail detached, causing the aircraft to crash.

Crew was engaged in a test flight. En route, unknown technical problems forced the crew to divert to Buffalo Airport. On landing, the aircraft went out of control, veered off runway and came to rest in flames. While both occupants were injured, the aircraft was destroyed by fire.

The crew was performing a test flight on this second prototype. Ten minutes after departure from Seattle-Boeing Field, the crew informed ATC that engine number one caught fire and attempted to return. At an altitude of 2,400 feet, pilot feathered the propeller and notified ATC that the fire was spreading quickly. One minute later, as it was about to land, the bomber struck a power line and crashed on an industrial butchery. Extensive emergency resources were dispatched to the scene where rescuers did not find any survivors among the debris scattered over a wide area. The building was destroyed as well and 34 dead bodies were found: all 11 occupants on board the airplane and 23 people on ground. Thirty others people were injured as well.
Crew:
Eddie Allen, Chief test pilot by Boeing,
Bob Dansfield, captain.

The crew was completing a test flight following maintenance. On final approach to Asmara Airport, at an altitude of 800 feet, the twin engine aircraft went out of control, dove into the ground and crashed in a huge explosion. Both crew members were killed.

While performing a test flight in the Milan area, the crew encountered fuel problems and was forced to attempt an emergency landing in a field. The aircraft was wrecked while all occupants escaped unhurt.