Factual Report: MU-2 loss of control

 - December 19, 2007, 12:08 PM

MITSUBISHI MU-2B-35, CAROLINA, PUERTO RICO, APRIL 15, 2002–Experiencing a loss of control while orbiting, Mitsubishi N45BS crashed into an automobile service facility near Carolina, Puerto Rico, at 3:03 p.m. IMC prevailed and no flight plan was filed for the Part 91 positioning flight from Rohlsen Airport (TISX), St. Croix, Virgin Islands, to Marin Airport (TJSJ), San Juan, Puerto Rico. The airplane, operated by Crucian Airlines, was destroyed by the crash and post-crash fire, and the ATP pilot, the sole occupant, was killed. One person at the automobile facility was killed and two others were injured.

At 1:45 p.m. the pilot had phoned San Juan FSS but did not obtain a preflight weather briefing. After departing from TISX, the flight was radar identified. At 2:59:16 the controller advised the pilot, “Hold [VFR] over plaza please make left [360s].” The pilot responded, and at 3:02:31 the controller advised him to hold south of the plaza. There was no response.

Several witnesses reported that there was light rain. One witness saw the airplane emerge from the clouds in a 45-degree left-wing-low and 20-degree nose-low attitude. He lost sight of the airplane but then it rolled to a wings-level attitude. He heard the engines “cutting in and out.” Another witness reported the same. A pilot-rated witness estimated the ceiling at 300 feet in light drizzle.

A special weather observation at San Juan seven minutes before the accident indicated the wind was from 080 degrees at 9 knots, visibility 10 statute miles, scattered clouds at 900 feet, a broken ceiling at 2,100 feet, overcast clouds at 4,500 feet, and temperature and dew point 24 and 23 degrees C, respectively. Doppler radar indicated that at 3:08 p.m. in the area and at the altitude the airplane was flying, a band of echoes with reflectivities in the range of NWS VIP Level 1 to 2 (very light to light to moderate) intensities were noted. The controller reported marginal VFR conditions existed at TJSJ.

Between 2:59:35 and 3:02:27, the airplane climbed from 1,300 to 1,500 feet, then descended to 800 feet. Between 3:02:27 and 3:02:35 (the last plotted altitude), the airplane descended from 800 to 200 feet, an average rate of descent of 4,500 fpm. During this time, the airplane was banked to the left in varying degrees of bank; the maximum left bank angle was approximately 48 degrees. The airspeed decreased and increased several times. From 3:02:10 to 3:02:27, the airspeed decreased from 160 to 100 knots and the angle of attack increased from 12 to 26 degrees. Between 3:02:30 and 3:02:35, the true heading changed, indicating a bank to the right.

The power-off stall speed was calculated to be 122 knots, and Vmc with 5 and 20 degrees flaps extended was 99 and 90 knots, respectively. An airspeed of approximately 123 knots was calculated from the distance between the parallel slash marks on the automobile facility roof.