NYC98FA073

"This case was modified August 2, 2006."

The Piper Apache was cruising at about 1,500 feet AGL, when a witness saw the vertical stabilizer start to oscillate and then separate from the airplane. The airplane descended and struck a multiple family dwelling. Examination of the wreckage revealed the outboard wing panels had separated from the airplane in flight due to downward bending forces that occurred after the in-flight separation of the horizontal stabilizer. The horizontal stabilizer was found next to the vertical stabilizer apart from the main fuselage and wing wreckage and had separated, in-flight, in a horizontal twisting motion that pushed the left tip of the horizontal stabilizer rearward. An impact mark on the left outboard leading edge of the horizontal stabilizer was consistent with a soft bodied impact that occurred prior to ground impact. Although one witness reported seeing several birds flying in the area at the time of the accident, examination of the left horizontal stabilizer and elevator failed to find any evidence of blood, feathers, or bird remains. A detailed and comprehensive examination of the accident site area failed to reveal any evidence of a bird carcass, or bird feathers. Aircraft components composed of both aluminum and fiberglass were mounted forward of the empennage, however the impact mark showed no residual evidence of being struck by either material. A determination of the source of the soft bodied impact could not be made. The vertical stabilizer is attached to the horizontal stabilizer, and this assembly is then attached to the fuselage through four attach points. The damage to the vertical stabilizer attach points indicates that they failed toward the left (as viewed from the rear looking forward) and were securely attached to the horizontal stabilizer at the time of failure. Three of the four bolts that attach the horizontal stabilizer to the fuselage were recovered. The forward two attach points were torn out of the horizontal stabilizer during the in-flight separation. Compression damage to the lower skin immediately forward of the aft, left attach point indicates that it was securely attached. No evidence was found to indicate that any of the attach points were unsecured prior to the accident.

"This case was modified August 2, 2006."

History of flight

On March 4, 1998, about 1410 eastern standard time, a Piper PA-23-160, N3374P, was destroyed when it struck a multiple family dwelling in Somerville, New Jersey. The certificated private pilot and pilot rated passenger were fatally injured. Visual meteorological conditions prevailed for the personal flight conducted under 14 CFR Part 91. No flight plan had been filed for the flight, which departed from Greenwood Lake Airport (4N1), West Milford, New Jersey, about 1350.

The flight originated from Marlboro Airport (2N8), Matawan, New Jersey, earlier in the day. The pilots flew to Old Bridge Airport (3N6), English Town, New Jersey, where the airplane was serviced with 50.1 gallons of 100 Low Lead aviation grade gasoline. The flight then departed for 4N1 where the pilots ate lunch, and then departed for Marlboro Airport.

Several witnesses in the accident site area observed the airplane. Most of the witnesses reported they heard a noise, looked up, and observed the airplane in a nose down attitude. Some reported it was spinning as it descended, while others reported seeing parts of the airplane descending. One witness located in a housing complex north of the accident site reported that he observed the airplane overfly his location heading to the south. After the airplane had passed his location, he continued to watch it. The witness observed the top of the tail start to oscillate with increasing intensity, and then the entire tail section separated from the airplane, after which the airplane nosed down.

Another witness located about 1/2 mile north of the accident site saw a large number of birds flying in the area, and then saw the airplane which she first thought was a bird. As she watched the airplane it suddenly dipped and then descended. She saw parts separate from the airplane and watched it until it disappeared from view. She said the birds were flying independently of each other not in a flock.

The airplane struck the roof of a multiple family condominium dwelling, and exited through the front wall. The airplane came to rest in the street in front of the building.

The accident occurred during the hours of daylight at 40 degrees, 30 minutes, 45.9 seconds North Latitude and 74 degrees, 38 minutes, 05.9 seconds West Longitude.

Other damage

The roof and front siding for the first and second floors of the condominiums at 485 and 487 Brookside Lane were damaged. The damage was estimated to be about $150,000.00.

Personnel information

The pilot held a private pilot certificate for airplane single and multi-engine land, and a mechanic certificate for airframe and powerplant. He was issued a third class FAA airman medical certificate with no limitation on August 26, 1996. The pilot's logbook was not recovered. According to his last FAA airman medical application, the pilot had a total time of 725 hours. The pilot's total multi-engine time was not determined. According to FAA records, his last flight review took place on September 26, 1996, when he received his multi-engine rating.

The pilot rated passenger held a commercial pilot certificate for airplane single and multi-engine land, private privileges for single engine sea, and instrument airplane. He also held a flight instructor certificate for airplane single engine land and instrument airplane. He was issued a first class FAA airman medical certificate with no limitation on November 5, 1997. According to his last FAA airman medical application, he had a total time of 1,010 hours. According to FAA records, his last flight review took place on March 11, 1997, when he renewed his flight instructor certificate.

Aircraft information

The airplane was a 1958 Piper PA-23-160, which had been modified by Supplemental Type Certificates (STC) which were known as a Geronimo Conversion. The investigation revealed that the registered owner had sold the airplane to the accident pilot. The contract was written so that the transfer of title would not take place until the final payment had been completed. The accident pilot was still making payments, and the registration remained in the name of the seller.

Radar and other remotely recorded data

Radar data was received from the New York Air Traffic Control Center in the National Track Analysis Program (NTAP) format. The data was changed from a latitude/longitude format to a X/Y format, with the accident site as the zero reference point.

A target that was using a transponder code of 1200 was identified traveling on a heading of about 160 degrees, between 2,000 feet mean sea level (msl), and 1,800 feet msl. The heading was consistent with witness statements. This was the only target that was near the accident site at the time of the accident. The last radar contact was recorded at 1411:42, when the target was .94 nautical miles northwest of the accident site, at an altitude of 1,800 feet msl. The estimated ground speed of the target was 146 knots.

Wreckage and impact information

The airplane was examined at the accident site on March 4, through March 6, 1998. The debris path, made up of three groupings, was along a heading of between 095 and 100 degrees magnetic with lighter objects further away than heavier objects. The first group consisted of the cockpit/cabin, aft fuselage, both inboard wing panels, the left aileron, and both engines and their propellers. This was found in front of the damaged residences. The next group consisted of outboard wing panels, both wing tips, the right aileron, the vertical stabilizer and rudder, the horizontal stabilizer and elevator, and the aft fuselage skin. The furthest objects were the two fiberglass wingtips, which were about 670 feet from the main wreckage. The third group consisted of paint chips that continued on a magnetic heading of about 099 degrees from the accident site for an additional 790 feet beyond the wing tips.

The roof of the airplane was pushed rearward and crushed, and the sides of the cabin were absent above about 18 inches. Both occupant seats in the airplane were broken loose from the their attach points. The right seat occupant was found restrained by his seat belt. The left seat occupant was found separated from his seat. A check of the left seat belt found it would latch and unlatch without problem.

The left and right engines were separated from their engine mounts. A tachometer cable remained attached between the right engine and the right engine firewall. Valve train continuity was verified for both engines. Compression was found in all cylinders. Spark was obtained from all terminals of all magnetos. Both engine oil screens were clear of debris. Fuel was found in the fuel lines and engine driven fuel pumps of both engines.

Both carburetors were broken open. The fuel screens in the carburetors were free of debris. The main jets were not clogged. Both carburetors had metal floats.

Both propellers had received impact damage. Chordwise scoring and leading edge damage was found on all blades. Blade bending was typically rearward along a broad arc radius. One blade of the right propeller also exhibited moderate torsional bending. The blade shanks of the propellers had rotated from their respective indexed position, with more slippage visible on the left engine propeller blades. The left propeller low pitch lock pins were engaged. The right propeller piston and pitch change links were destroyed.

The mixtures were found in the full forward position, and the throttles were mid-range with the right throttle about 1 inch ahead of the left throttle. The left propeller control was mid-range, and the right propeller control was in the feathered position. The magneto switches were non-locking toggle switches with up for ON and down for OFF. The left magneto switch of the left engine was not identi