Accident Sequence
The aircraft, registered as N292HH, experienced an in-flight breakup while on a visual approach to runway 01L. Radar data showed that N292HH crossed the flight path of a Boeing 737, which was landing on parallel runway 01R, on two occasions. The first crossing occurred at approximately 1910:48 at an altitude of about 3,900 feet MSL and an airspeed of 158 KCAS. The Boeing 737 had passed the same geographic point about 2 minutes and 9 seconds earlier at 5,500 feet MSL. The second crossing occurred at 1911:25 at an altitude of about 3,300 feet MSL and an airspeed of 183 KCAS, with the Boeing 737 having passed approximately 1 minute and 55 seconds prior at 3,900 feet MSL. At the time, the Boeing 737 was on a north-northwesterly heading, while N292HH was on a northwesterly heading. After the second crossing, N292HH continued to the west of the Boeing's path. The last radar contact with N292HH was at 1911:34 at an altitude of 3,128 feet MSL and an airspeed of 183 KCAS, located 0.32 miles west of the Boeing's flight path.
Aircraft and Performance Data
According to the Pilot's Operating Handbook for N292HH, the never-exceed speed (Vne) was 189 KCAS. The maximum structural cruising speed was 165 KCAS, and the design maneuvering speed (Va) was 132 KCAS at 3,600 pounds and 104 KCAS at 2,230 pounds. The last recorded airspeed of N292HH was 183 KCAS.
Wreckage and Material Examination
All wreckage was located in a single open field. The left wing, both left and right sides of the stabilator, and portions of the right wing flap and aileron had separated in flight. The inboard sections of the left and right stabilator along with the separated section of the left wing spar were sent to the NTSB Material Laboratory for examination. The examination determined that all separations were due to overload.
Meteorological Conditions
Hourly weather observations taken before and after the accident indicated winds from the northeast at 9 to 10 knots.
Relevant Guidance
FAA Advisory Circular (AC) 90-23F addresses aircraft wake turbulence. It states that vortices from larger aircraft sink at several hundred feet per minute, diminishing in strength with time and distance. It advises pilots to fly at or above the preceding aircraft's flight path and alter course as necessary to avoid areas behind and below the generating aircraft. The circular emphasizes that pilots are expected to adjust operations and flight paths as necessary to preclude serious wake encounters, whether or not a warning has been given.