Introduction
On February 24, 2017, at 1823 eastern standard time, a Robinson R-44 helicopter, registration N44EK, collided with buildings and terrain after performing a forced autorotation landing near Chatham, New Jersey. The private pilot received minor injuries, and the passenger was seriously injured. The helicopter was registered to N44EK Inc. and operated under 14 CFR Part 91 as a personal flight. Night visual flight rules conditions prevailed, and no flight plan was filed.
Flight History
The flight originated at Millville Municipal Airport (MIV), Millville, New Jersey, about 1745, en route to Lincoln Park Airport (N07), Lincoln Park, New Jersey, about 101 nautical miles away. Earlier, the pilot and passenger had departed from Richmond Executive Airport-Chesterfield County (FCI), Richmond, Virginia, and stopped at MIV for fuel. The pilot purchased 24.1 gallons of 100 low-lead aviation fuel about 1730.
Accident Sequence
During cruise flight from MIV to N07, the pilot was transitioning near Morristown Municipal Airport (MMU) at about 1,800 feet mean sea level when the engine stopped producing power. The low RPM warning horn sounded. The pilot lowered the collective and entered an autorotation. The area was congested and it was nighttime. The pilot spotted a clear area between two single-story garages but struck one building during the forced landing and lost control. The passenger reported hearing a "whoosh" before the engine lost power.
Air traffic control transcripts show that at 1819:24, the pilot reported to MMU tower: "two thousand three hundred, we're on the way down to eighteen hundred, four four echo kilo." At 1823:37, the pilot stated: "uh Morristown, helicopter four four echo kilo, we are going to make an autorotation, we don't know where we are." He repeated "we're making an autorotation" and then reported "emergency going down."
A witness in a nearby apartment building heard the helicopter with "engine missing or sputtering," then heard it pass overhead and the collision.
Personnel and Aircraft Information
The pilot held a private pilot certificate with a rotorcraft-helicopter rating. He had about 1,600 total flight hours, including 1,100 hours in the Robinson R-44. The helicopter, manufactured in 1999, was a four-place, two-blade aircraft powered by a 225 HP Lycoming O-540 engine. The engine had accumulated 5.9 hours since a major overhaul on March 7, 2016. The airframe was overhauled and inspected on January 16, 2017, with about 2,000 total airframe hours. The helicopter was purchased on December 15, 2016.
Meteorological Information
At 1845, weather at MMU (4 miles north-northwest of the accident site) included wind from 180° at 7 knots, visibility 15 statute miles, few clouds at 6,000 feet, temperature 20°C, dew point 12°C, and an altimeter setting of 28.84 inches of mercury.
Wreckage and Engine Examination
The helicopter struck the roof of a single-story garage and came to rest on an asphalt access road. The tail rotor separated about 5 feet from the tail, and main rotor blades were bent. Fuselage had multiple buckles, landing skids were flattened. Fuel tanks were intact with blue fuel; samples showed no contaminants.
All major components were accounted for. Examination revealed that when the crankshaft was rotated, only cylinder No. 5 showed thumb compression; no other cylinders had compression. The crankshaft gear bolt was about 3/16 inch from its seated position. The safety lockplate washer exhibited wear, and rotational scoring was noted on the bolt head. The bolt's bottom threads were damaged, and the alignment dowel was sheared.
Lycoming's mandatory service bulletin SB475C (issued January 23, 2003) specifies proper assembly procedures for the crankshaft gear, noting that improper assembly can lead to gear failure and complete engine stoppage. The assembly procedures include tightening the bolt to specified torque, checking gear seating with a feeler gauge, and using new lockplates and bolts.