Accident Overview
The twin-engine airplane collided with the ground during an uncontrolled descent while maneuvering in dark night instrument meteorological conditions near Lewisville, Texas. The commercial pilot had contacted the approach controller and reported that his attitude indicator was "not helping" and requested assistance with maintaining straight flight. The controller instructed the pilot to maintain 3,000 feet mean sea level and later directed turns, which were acknowledged. No further communications occurred after the last instruction.
Impact Details
The airplane initially struck the ground in a near-vertical attitude in a wooded area adjacent to a rural paved road, then slid across the road and collided with a residence.
Evidence and Examination
Radar data indicated the aircraft's magnetic heading was erratic throughout the five-minute flight. Gyroscopic instruments recovered at the accident site included the copilot's direction gyro (vacuum-driven), a turn and bank indicator (electric), and the pilot's attitude indicator (vacuum-driven). Disassembly and visual inspection revealed the copilot's direction gyro had rotation signatures on the gyro and housing. The turn and bank indicator showed a "faint" rotational signature. The pilot's attitude indicator gyro exhibited no rotational signatures and had blunt impressions matching the gyro buckets on the housing interior. A maintenance repair data plate marked "Functional Tested" dated December 2, 2002, was found on the attitude indicator. Due to extensive fire damage, no instrument readings could be obtained.
Pre-Accident Maintenance
Seven days before the accident, a company pilot who flew the accident airplane reported that the pilot's attitude indicator (part number 102-0041-04, serial number 92B0346) "rotated," prompting an aborted flight. The next day, the instrument was removed, bench checked, cleaned, and adjusted, then reinstalled and operationally checked on the ground. Three days prior to the accident, the attitude indicator was again removed for overhaul. Company maintenance personnel stated it was reinstalled the night before the accident morning and a ground operational check was performed.
Physical and Radar Findings
Radar data showed the aircraft did not stabilize on any heading throughout the flight. Physical evidence confirmed that the pilot's attitude gyro was not spinning at the time of impact.