19981104031369A

Acft crash laned on a street for unkn reasons. (.19) on November 4, 1998, about 1428 eastern standard time, a Schweizer 269C, N2100B, was destroyed as it impacted the terrain during a forced landing in Baltimore, Maryland. The certificated commercial pilot/police officer was fatally injured and the aerial observer received serious injuries. The helicopter, owned by U.S. Leaseco inc., maintained by helicopter transport services, inc., was operated by the Baltimore police department helicopter unit and was performing an official police mission at the time of the accident. Visual meteorological conditions prevailed and no flight plan was filed for the public use flight conducted under 14 CFR part 91. According to the helicopter logbook, the same aircrew had flown the helicopter that morning for 2 1/2 hours, and no discrepancies were written in either the airframe or the engine logs. According to maintenance company personnel, the helicopter departed martin state airport, about 1300. At 1420, a police ground unit requested assistance from the aircrew to track a stolen vehicle. According to supporting ground units, the stolen vehicle had stopped at an intersection and the helicopter entered a left orbit. A police officer, located about two city blocks west of the stolen vehicle stated: "...(I heard) something on the radio. I am not sure if it was a ground unit or fox (the helicopter). Out of the corner of my eye I observed something, I glanced up and saw (the helicopter) coming down. It appeared that the rotor blade...wasn't spinning normally. It appeared to be slow." Other witnesses reported hearing a loud pop and seeing smoke trailing from the helicopter. A police officer reported that "the helicopter made a sharp hook through two buildings and hit the street approximately 5 feet in front of my car." Ground scarring and debris found in the street indicated a southerly direction. A tree 20 feet south of a townhouse had fresh clippings, and a metal light pole about 30 feet south of the tree was lying in the street, and exhibited impact marks with blue paint similar to that of the helicopter. Impact marks, resembling metal to asphalt contact, were found on the street with the main wreckage found about 40 feet further south. The helicopter came to rest lying on its right side and on top of a 10 foot section of a wrought iron fence. The landing skids were fractured into numerous pieces, and the tail boom was separated from the structure and lodged in the cabin. The field examination of the wreckage disclosed no evidence of mechanical malfunction of the main rotor, the tail rotor, the drive system, the flight controls and the fuselage. A 2 inch hole found on the bottom of the engine casing, was located near the number 2 cylinder. Removal of a protective shield on top of the engine disclosed a 4 inch hole on the top of the casing for the same cylinder. The engine, a HIO-360-D1A, manufactured by the Textron Lycoming on February 13, 1998, was installed by helicopter transport services on October 22, 1998. The engine accumulated about 45 hours of flight time prior to the accident, and the airframe had 725 total hours. The engine was removed for further examination. (-23)the Baltimore City police helicopter made an attempted emergency landing in the 900 block of west pratt street. Witnesses reported hearing popping noises and seeing smoke. The helicopter was destroyed during the attempted landing. (.4)the police helicopter was performing a police mission less than 500 above ground level when the engine lost power. The pilot was unable to reach a suitable landing area and maintain rotor RPM. The helicopter struck trees and a light pole, landed hard on a road, and slid into a fence. Examination revealed the #2 connecting rod had separated from the crankshaft. A torque check on the remaining connecting rod bolts found all below the minimum specified. A work action (strike) had been in effect at the engine manufacturer at the time of engine assembly, and production continued with management and replacement workers. During assembly the crankshaft had been replaced for an unknown reason. After the crankshaft was replaced, new connecting rods were attached, but not properly tightened. Replacement workers manned the two assembly stations identified as most probable for replacement of the crankshaft and failure to tighten the connecting rod bolts. Although long time employees knew the correct procedures for documentation of a replaced crankshaft, no specific written instructions were available for the replacement employees. The engine failed at 45.7 hours total time.