LAX84FU022

After purchasing the 2 eng ultralight, the plt modified it by installing 2 additional engs. These were 6 HP pioneer engsinstalled in the #1 & #4 positions. Just prior to the accident, witnesses observed the vehicle flying over the center ofa lake at aprx 250 ft & at hi speed. Reportedly, it entered a right bank, which continued, and subsequently, the vehicledescended & struck the water in a nose 1st attitude. An investigation revealed that on at least 2 occasions, an outboardeng had inadvertently shut down, inflt. A friend of the plt had flown this same vehicle & had experienced an outboard eng shutdown. He confirmed that full opposite rudder was required to maintain control. All propellers were found broken,except #4 which was not damaged. Flexible fuel lines were found inserted in the fuel tank to pickup fuel for the #1 & #4ENGS; however, they were not secured to assure proper depth. The vehicle was not equipped with a shoulder harness. The plt had not received any known plt ground training. He had flown the acft aprx 5 hrs after it was modified with 4 engs.