History of Flight
On September 8, 2017, about 1300 eastern daylight time, a Schweizer 269C-1 helicopter (registration N204HF) was substantially damaged when it collided with terrain during a forced landing to runway 01 at Flying W Airport (N14) in Medford, New Jersey. The commercial pilot and passenger sustained fatal injuries. The helicopter was owned by Herlihy Helicopters Inc and operated by Helicopter Flight Services under 14 CFR Part 91. Visual meteorological conditions prevailed; no flight plan was filed.
The flight was intended as an orientation/pleasure flight for a passenger scheduled to perform at a concert on the airport later that evening, according to the operator's chief flight instructor.
Minutes after takeoff, the pilot reported over the UNICOM frequency that he could not control engine rpm with throttle inputs. He stated that he could rotate the twist-grip but observed no corresponding change in engine rpm.
The company flight instructor and another instructor who was a designated pilot examiner (DPE) were monitoring the frequency and discussed potential courses of action with the pilot. A Federal Aviation Administration (FAA) inspector, also a helicopter instructor, joined the conversation.
Options included a shallow approach for a run-on landing or a power-off autorotational descent. The instructors recommended a run-on landing, but the pilot reported a previous attempt had failed and announced he would stop the engine and perform a power-off autorotation, a procedure he said he had performed numerous times. When asked when he last performed a touchdown autorotation, the pilot replied 4 months prior. Attempts to persuade him to attempt a run-on landing were unsuccessful.
The DPE and FAA inspector advised the pilot multiple times to aim for a midfield touchdown and not to initiate engine shutdown until over the runway. The DPE's last reminder came when the helicopter was on a 2-mile final approach.
A video recorded from a vantage point near the approach end of runway 01 showed the helicopter about 1/4 mile south of the runway entering a descent profile consistent with an autorotation. The descent became more vertical, and the rate of descent increased before the helicopter descended out of view. No helicopter sound was audible.
Postaccident, the company flight instructor reported that the autorotation began about 950 ft above ground level and the helicopter was quiet during descent because the engine was off. Rotor rpm decayed to the point where individual blades were visible. The helicopter descended from view before reaching the runway threshold, and impact sounds were heard. Both the instructor and FAA inspector reported a high-pitched "whine" during the latter portion of the descent.
The flight instructor wrote that the autorotation was not executed correctly; vertical speed increased and horizontal speed became nearly zero. The nose rolled forward, and he could see only the cockpit glass and rotor head instead of the helicopter's bottom.
Personnel Information
The pilot held commercial and flight instructor certificates with rotorcraft-helicopter and instrument-helicopter ratings. His most recent FAA second-class medical certificate was issued April 12, 2017. His logbook showed 480.9 total flight hours, about 300 in the accident make and model. The last entry was 1.2 hours on the accident day. Company training records indicated required training and a satisfactory airman competency check on April 19, 2017, in the accident helicopter.
Aircraft Information
The helicopter was a single-engine, two-seat Schweizer 269C-1, powered by a Lycoming HO-360-C1A 180-horsepower engine. It had a fully articulated three-blade main rotor and a two-blade tail rotor. Power was transmitted via a V-belt drive with a free-wheeling sprag clutch.
Manufactured in 2000, the helicopter had accumulated about 7,899 total hours. Its most recent 100-hour inspection was on August 17, 2017, at 7,884 hours. Engine replacements occurred in 2003, 2006, and most recently on September 24, 2011. Numerous carburetor discrepancies were recorded; carburetors were adjusted or replaced. A throttle control cable from McFarlane Aviation Products was installed on August 31, 2016, under an FAA Form 337, requiring inspection at 25-hour intervals; the most recent inspection was 15 hours before the accident.
During an interview, the operator stated that when engines were changed, the throttle control system components remained attached to the helicopter, and no throttle rigging adjustments were necessary except measuring the throttle control arm angle and idle/mixture adjustments. He described the cable installation as "plug and play" with no rigging changes. When asked about verifying throttle rigging after the last engine change, he said, "I don't know if I did... but I'm not 100 percent [sure]."
The manufacturer's maintenance manual required throttle rigging verification after engine, throttle cable, or carburetor installation.
Meteorological and Airport Information
At 1254, weather at South Jersey Regional Airport (VAY), 2 miles west of N14, was clear skies, wind 260° at 13 knots gusting to 18 knots, temperature 21°C, dew point 9°C, altimeter 30.13 inHg.
N14 had elevation 49 ft and a single runway 01/19. The operator's hangar was at the south end, abeam runway 01 numbers. A creek oriented east-west crossed about 200 ft south of the approach end, lined with small trees and brush, bisecting an open field south of the airport. The field was about 1,400 ft long and 300 ft wide, oriented similarly to the runway, with a surface of mowed grass or scraped soil.
Wreckage and Impact Information
The initial ground scar was about 10 ft before the main wreckage, which was about 220 ft from the runway 01 threshold, aligned with the runway. The cockpit was significantly deformed, the tailboom separated from the fuselage. The engine and main transmission remained mounted. Main rotor blades remained attached; the yellow blade's pitch-change link was fractured from overstress. All three blades were bent at the root with little spanwise damage, consistent with low rotor rpm at ground contact.
Flight control continuity was established through breaks. Both throttles moved together when the pilot's throttle was actuated, but movement was limited due to collective damage. The throttle cable continuity was confirmed from the collective jackshaft to the throttle bellcrank assembly, which was intact but separated from its fractured mount. The internally threaded portion of the two-piece throttle tie rod was attached to the bellcrank and filled with organic material resembling roots from the impact crater.
Drivetrain continuity was established; the main gearbox rotated freely, and the free-wheeling sprag clutch operated correctly. The engine was rotated by hand; compression and spark were confirmed. The carburetor was separated, displaying impact damage; its externally threaded tie rod portion remained attached to the throttle arm. Throttle and mixture arms moved smoothly. The filter screen was debris-free, and fuel appeared clear.
Components including the collective, jackshaft, throttle cable, bellcrank assemblies, and both halves of the throttle tie rod were retained for NTSB Materials Laboratory examination.
Medical and Pathological Information
An autopsy by the Burlington County Medical Examiner listed the cause of death as "multiple injuries." Toxicological testing was negative for drugs and alcohol.
Tests and Research
The throttle tie rod assembly was received separated at the threaded joint. The internally threaded rod attached to the bellcrank and the externally threaded rod-end bearing with jam nut attached to the throttle arm were separated. The jam nut was found midway between the threaded end and the rod end bearing eye.
Magnified examination of the externally threaded rod-end bearing revealed mechanical damage (thread-to-thread wear) on the three end threads. The internal threads of the rod contained embedded cellulose material; after cleaning, the three end threads showed pock-marks and reduced flank size, consistent with vibratory wear. Threads further inside were undamaged and shiny.
An exemplar Schweizer 269C-1 was examined to confirm rigging. The throttle tie rod length was set to 4.97 inches; the engine idled at 1,000 rpm. When the tie rod was adjusted to 5.5 inches (approximate length of the accident tie rod), the engine idled at 1,100 rpm. The maintenance manual specified idle speed adjustments after rigging.
Sikorsky issued Alert Service Bulletin ASB-C1B-048 on November 16, 2017, for a one-time inspection of the throttle control tie rod assembly length.
Organizational and Management Information
The owner of Helicopter Flight Services held multiple certificates, including mechanic with inspection authorization, and performed much of the accident helicopter's maintenance, including the most recent throttle cable inspection.
Additional Information
The US Army Hughes TH-55A manual stated that if the throttle becomes inoperative, continue to a landing area permitting a shallow approach and running landing. The manufacturer's Pilot's Flight Manual did not contain a throttle failure emergency procedure. A survey of two other piston-helicopter manufacturers by the FAA inspector revealed they also did not publish such a procedure.
The US Army Training Circular provided guidance on autorotation, including the exchange of altitude for rotor rpm, the circle of action, and landing procedures in the last 50-100 feet. FAA Advisory Circular 61-140 indicated that failure to maintain rotor rpm and airspeed during autorotation training was a predominant cause of accidents. The FAA Helicopter Handbook noted that premature collective application could deplete kinetic energy, resulting in hard landings.