What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Aircraft was in cruise at 8500 ft MSL, en route from btv to dmw, and diverted to avp due to a rough running engine. Aircraft lost communications with the tower, and crashed into a residential neighborhood approximately 5 miles from avp, striking a power line pole with the right outboard wing, substantially damaging the right wing and knocking the pole down, then, striking the ground and a power line pole with the left outboard wing, separating the outboard section of wing and aileron from the aircraft. The aircraft slid and spun to a stop approx. 175 ft. from the initial point of ground contact. No fire was observed and no ground injuries were reported.
During interview, the pilot rated passenger stated that she was in the left seat during the accident flight and acting as PIC until the engine started to lose power and an in-flight emergency was declared. Flying at cruise and attempting to lean the engine, they noticed the #2 cylinder EGT drop to -270F from peak, followed by vibration. At that point, the owner took the controls and she declared an ife. The owner told her that they had enough altitude and power to make it to avp, 22NM out, and maintained 100 mph glide speed per the afm/poh. They soon rapidly lost cylinder #1, followed by a loss of oil pressure, and an uncontrollable prop overspeed unless engine power was reduced to minimum. She then noticed smoke in the cockpit and opened a vent window. Realizing that they would not make avp with total loss of engine power, they prepared for an alternate, off-field landing, focusing on a parking lot until noticing a large building between them and said parking lot. The accident location then became the best option as they could see power poles and lines down the left side of the street, but the right appeared clear. They noticed the single pole on the right side of the street at the last moment, just prior to initial contact.
Aircraft inspection revealed the #2 cylinder separated from the case approx. 2 inches, breaking the upper studs, and breaking the left case close to the four lower studs, leaving the studs intact. The piston was still inside the cylinder, and the piston/connecting rod assy. Was still intact and connected to the crankshaft. Minor mechanical damage to the connecting rod and a broken piston skirt were also noted. Two upper studs were noted to have 3-4 course threads showing (course threads thread into the case), and the inspector could turn one stud by hand. Further inspection revealed excessive heat damage due to oil loss to the lower connecting rod, crankshaft, and visible portion of the #1 cylinder connecting rod.
As the FAA filed it
AIRCRAFT WAS IN CRUISE AT 8500 FT MSL, EN ROUTE FROM BTV TO DMW, AND DIVERTED TO AVP DUE TO A ROUGH RUNNING ENGINE. AIRCRAFT LOST COMMUNICATIONS WITH THE TOWER, AND CRASHED INTO A RESIDENTIAL NEIGHBORHOOD APPROXIMATELY 5 MILES FROM AVP, STRIKING A POWER LINE POLE WITH THE RIGHT OUTBOARD WING, SUBSTANTIALLY DAMAGING THE RIGHT WING AND KNOCKING THE POLE DOWN, THEN, STRIKING THE GROUND AND A POWER LINE POLE WITH THE LEFT OUTBOARD WING, SEPARATING THE OUTBOARD SECTION OF WING AND AILERON FROM THE AIRCRAFT. THE AIRCRAFT SLID AND SPUN TO A STOP APPROX. 175 FT. FROM THE INITIAL POINT OF GROUND CONTACT. NO FIRE WAS OBSERVED AND NO GROUND INJURIES WERE REPORTED.
DURING INTERVIEW, THE PILOT RATED PASSENGER STATED THAT SHE WAS IN THE LEFT SEAT DURING THE ACCIDENT FLIGHT AND ACTING AS PIC UNTIL THE ENGINE STARTED TO LOSE POWER AND AN IN-FLIGHT EMERGENCY WAS DECLARED. FLYING AT CRUISE AND ATTEMPTING TO LEAN THE ENGINE, THEY NOTICED THE #2 CYLINDER EGT DROP TO -270F FROM PEAK, FOLLOWED BY VIBRATION. AT THAT POINT, THE OWNER TOOK THE CONTROLS AND SHE DECLARED AN IFE. THE OWNER TOLD HER THAT THEY HAD ENOUGH ALTITUDE AND POWER TO MAKE IT TO AVP, 22NM OUT, AND MAINTAINED 100 MPH GLIDE SPEED PER THE AFM/POH. THEY SOON RAPIDLY LOST CYLINDER #1, FOLLOWED BY A LOSS OF OIL PRESSURE, AND AN UNCONTROLLABLE PROP OVERSPEED UNLESS ENGINE POWER WAS REDUCED TO MINIMUM. SHE THEN NOTICED SMOKE IN THE COCKPIT AND OPENED A VENT WINDOW. REALIZING THAT THEY WOULD NOT MAKE AVP WITH TOTAL LOSS OF ENGINE POWER, THEY PREPARED FOR AN ALTERNATE, OFF-FIELD LANDING, FOCUSING ON A PARKING LOT UNTIL NOTICING A LARGE BUILDING BETWEEN THEM AND SAID PARKING LOT. THE ACCIDENT LOCATION THEN BECAME THE BEST OPTION AS THEY COULD SEE POWER POLES AND LINES DOWN THE LEFT SIDE OF THE STREET, BUT THE RIGHT APPEARED CLEAR. THEY NOTICED THE SINGLE POLE ON THE RIGHT SIDE OF THE STREET AT THE LAST MOMENT, JUST PRIOR TO INITIAL CONTACT.
AIRCRAFT INSPECTION REVEALED THE #2 CYLINDER SEPARATED FROM THE CASE APPROX. 2 INCHES, BREAKING THE UPPER STUDS, AND BREAKING THE LEFT CASE CLOSE TO THE FOUR LOWER STUDS, LEAVING THE STUDS INTACT. THE PISTON WAS STILL INSIDE THE CYLINDER, AND THE PISTON/CONNECTING ROD ASSY. WAS STILL INTACT AND CONNECTED TO THE CRANKSHAFT. MINOR MECHANICAL DAMAGE TO THE CONNECTING ROD AND A BROKEN PISTON SKIRT WERE ALSO NOTED. TWO UPPER STUDS WERE NOTED TO HAVE 3-4 COURSE THREADS SHOWING (COURSE THREADS THREAD INTO THE CASE), AND THE INSPECTOR COULD TURN ONE STUD BY HAND. FURTHER INSPECTION REVEALED EXCESSIVE HEAT DAMAGE DUE TO OIL LOSS TO THE LOWER CONNECTING ROD, CRANKSHAFT, AND VISIBLE PORTION OF THE #1 CYLINDER CONNECTING ROD.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.
Other reports on N3790T · 3
Matched to the same aircraft by N-number and date.