Aviation Accident Summaries

Aviation Accident Summary CEN21LA109

Albany, TX, USA

Aircraft #1

N322SH

ROBINSON HELICOPTER R44 II

Analysis

The pilot reported that it was the second flight of the day. After an uneventful first flight, the helicopter returned to the airport to refuel and pick up new passengers. The purpose of the flight was to hunt game. As the passengers were getting into the helicopter, a rifle was dropped on the dash of the helicopter which turned the alt switch, master switch, and clutch switch to off. The pilot immediately turned the switches back on and conducted a hover power and final systems check. The helicopter then took off uneventfully. About 120 ft above the ground, the engine sputtered once then lost complete power. The pilot performed a left turning autorotation to a field. During the descent, the pilot increased the throttle, but the engine did not respond. The helicopter impacted trees before it landed hard on a small mound of dirt and came to rest nose low. During the impact sequence, the main rotor blade contacted and severed the tail boom. The pilot never reported that he conducted the ‘starting engine and run up’ checklist before taking off. This was confirmed by an onboard video. The video also showed the ignition switch in OFF throughout the flight, the impact, and following the accident sequence. During a postaccident engine run, the engine started uneventfully, and a magneto check was completed. When the ignition switch was in the right magneto position the engine rpm stayed the same instead of decreasing, indicating the magneto was not properly grounding. In addition, the engine continued to run despite the ignition switch being in the off position, indicating the engine was operating on one magneto. The ignition switch key was jiggled, manipulated, and even removed from the ignition switch, but the engine continued to run. The engine was shut down and electrical continuity was established from the ignition switch to the magnetos. The magneto grounding wires were examined and appeared to be properly secured. The wiring was tested with a volt/ohm meter and functioned normally. The grounding wires were reinstalled, and the engine was restarted. It operated normally and several magneto checks were normal. The magnetos were removed for a functional bench test and disassembly; no anomalies were noted with either magneto. The ignition switch was also removed, disassembled, and examined. No anomalies were found. Even though functional and disassembly tests did not indicate a problem with the magnetos themselves, the right magneto did not ground appropriately during the initial engine run. The anomaly was unable to be recreated after the magneto grounding wires were removed and reinstalled. Because the pilot did not perform all the required pretakeoff checks to ensure all the switches were in the correct positions prior to takeoff, the helicopter took off with the ignition switch in the OFF position. An undefined issue with the grounding wire caused the right magneto to not ground and allowed the helicopter to operate with the ignition in the “off” position. The magneto likely grounded during the initial climb, and since the ignition switch was in the OFF position, the engine shut down.

Factual Information

On January 9, 2021, about 1000 central standard time, a Robinson R44II helicopter, N322SH, was substantially damaged when it was involved in an accident near Albany, Texas. The pilot and two passengers were not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 hog hunting flight. The pilot reported that it was the second flight of the day. After an uneventful first flight, the helicopter returned to the airport to refuel and pick up new passengers. As the passengers were getting into the helicopter, a rifle was dropped on the dash of the helicopter. “The alt switch, master switch, and clutch [were] switch off” After turning the switches back on, the pilot conducted a “hover power and final systems check.” The helicopter then took off uneventfully. The pilot reported that when 120 ft above the ground, the engine sputtered once then lost complete power. The pilot performed a left turning autorotation to a field. During the descent, the pilot increased the throttle, but the engine did not respond. The helicopter impacted trees before it landed hard on a small mound of dirt and came to rest nose low. The main rotor blade contacted, and severed, the tail boom. Video of the accident flight begins with the helicopter on the ramp with the engine running with the magneto key in what appears to be the OFF position. In addition, as the pilot shuts down the helicopter after impact, the position of the key did not appear to move despite his fingers touching the key. During a postaccident examination of the airframe and engine, the helicopter was prepped for an engine run. It started normally and idled for a short time, then a magneto check was conducted. The engine rpm decreased when the key was turned to the left magneto position; however, the rpm remained the same when the right magneto was selected. The key was then moved to the OFF position, and the engine continued to run. The key was jiggled, manipulated, and even removed from the ignition switch, but the engine continued to run. The engine was shut down, and electrical continuity was established from the ignition switch to the magnetos. The grounding wires on the magnetos were examined and appeared to be properly secured. The wires were disconnected; they were pulled and manipulated with no anomalies noted. The magneto grounding wires were tested with a volt/ohm meter and functioned normally. The grounding wires were reinstalled for each magneto and the engine was restarted. It operated normally with several normal magneto checks. The magnetos were removed from the engine and the caps were removed; there were no obvious anomalies noted with the internal components. The ignition switch was also removed and disassembled, with no anomalies noted. The magnetos were removed for a functional bench test and disassembly. During the bench test, their temperature was increased to 190° F and the magnetos performed normally. Disassembly of the magnetos did not reveal any anomalies with the E-gap, contact settings, condensers, coils, and distributor gear timing that would have precluded normal operations. In the Robinson R-44II Pilot operating handbook the “STARTING ENGINE AND RUN-UP” checklist includes: “Ignition switch…Prime, then Both,” and “Mag drop at 75% RPM….7% max in 2 seconds.” Both checklist items involve manipulating the key prior to takeoff.

Probable Cause and Findings

The pilot’s inadequate pretakeoff checks which resulted in the magneto switch (key) remaining in the OFF position during the takeoff sequence and initial climb and the right magneto grounding intermittently.

 

Source: NTSB Aviation Accident Database

Get all the details on your iPhone or iPad with:

Aviation Accidents App

In-Depth Access to Aviation Accident Reports