LAX04GA243 · WSK PZL Mielec M-18A

Following a fire retardant drop, the airplane pitched nose up about 10 degrees, and then the nose dropped down 45 degrees, and the airplane descended into the ground. Drop altitude was about 100 feet above ground level (agl), and the ground sloped down about 20 degrees throughout the drop zone. The pilot made one practice dry run at his request. On the second pass, the pilot told the tactical air controller that he overshot final, and was going around. On the third pass, the pilot called downwind, base, and final. The pilot made no other transmissions, and did not indicate that he was having any problems. Witnesses saw the retardant exit the airplane; however, the drop was not at the desired point, and not distributed in an even line as the pilot's previous drops had been. The drop angled about 10 degrees to the final approach course. The drop pattern was wide and heavy at the beginning, and narrow and thin at the end. This indicated that the pilot initiated the drop early while turning onto final. About 2 seconds after the drop, the nose of the airplane pitched up slightly, which was normal after a drop. The nose of the airplane then pitched down about 45 degrees. The airplane maintained this attitude until ground impact. A prominent bend of the propeller shaft and a twist in the vertical splines indicated that the engine was generating high power. Post flight examination of the wreckage did not reveal any anomalies with the flight control system. Stall speeds with vortex generators installed varied from 73 mph in the clean configuration to 72 mph with full flaps. Drop techniques, airspeed, and flap settings varied among Dromadier pilots. Some pilots flew at airspeeds of 85 to 90 mph to lesson the pitch up on pull out. The M-18 operator's manual indicated that, with the sudden shift in CG at retardant release, the airplane would pitch up, and airspeed could decrease as much as 12 mph.

Verbatim NTSB analysis and probable cause from the NTSB dataset