What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(.4) Witnesses heard the vintage wwii trainer taking off at night. They reported that during the initial climb, the engine sound varied from high to low RPM 4 times, then they heard the airplane collide with the two-story apartment building. A pilot approaching to land at the departure airport reported seeing the accident airplane at low altitude and '...not climbing or climbing at a very shallow angle.' Other witnesses described the engine as 'sputtering' and 'backfiring.' An on-scene investigation revealed that the engine's 10:1 collector intermediate gear had two teeth missing. Metallurgical examination of the fractures by the safety board revealed features consistent with overstress separation.
As the FAA filed it
(.4) WITNESSES HEARD THE VINTAGE WWII TRAINER TAKING OFF AT NIGHT. THEY REPORTED THAT DURING THE INITIAL CLIMB, THE ENGINE SOUND VARIED FROM HIGH TO LOW RPM 4 TIMES, THEN THEY HEARD THE AIRPLANE COLLIDE WITH THE TWO-STORY APARTMENT BUILDING. A PILOT APPROACHING TO LAND AT THE DEPARTURE AIRPORT REPORTED SEEING THE ACCIDENT AIRPLANE AT LOW ALTITUDE AND '...NOT CLIMBING OR CLIMBING AT A VERY SHALLOW ANGLE.' OTHER WITNESSES DESCRIBED THE ENGINE AS 'SPUTTERING' AND 'BACKFIRING.' AN ON-SCENE INVESTIGATION REVEALED THAT THE ENGINE'S 10:1 COLLECTOR INTERMEDIATE GEAR HAD TWO TEETH MISSING. METALLURGICAL EXAMINATION OF THE FRACTURES BY THE SAFETY BOARD REVEALED FEATURES CONSISTENT WITH OVERSTRESS SEPARATION.