Accident Recovery: Split-Second Save Pilot’s experience, skill enabled him to counter low‑altitude downdrafts, preventing a more serious accident. By David Jack Kenny A saying popular among old-time airline pilots held that the first thing to do in an emergency was to wind the clock on the instrument panel. Avoiding hasty decisions reduces the risk of making a bad situation worse by hurrying to do the wrong thing. Not all emergencies, though, offer the luxury of time, particularly the time provided by altitude. When terra firma that’s already uncomfortably close suddenly starts rushing closer, only a reaction that’s both immediate and correct offers the chance to prevent a bad situation from quickly becoming a great deal worse. The Mission On the evening of Aug. 31, 2022, a wildfire was discovered on the south side of Mount St. Helens in the Cascade Range in southwest Washington state. A Sep. 7 update from the US Forest Service reported that the fire, “currently estimated to be about four acres in size … is located above a cliff, so fire personnel are only able to engage the fire on the upper portions of the slope due to the steep, rocky terrain. … Fire crews have been successful using helicopter bucket drops … to slow the fire’s spread.” The fire’s behavior was described as “smoldering and creeping,” but a week later an update from the Northwest Interagency Coordination Center estimated that the blaze, named the Kalama Fire, had grown to 112 acres. The operator of a Bell 205A-1 under contract to provide fire-suppression services was called in. The Aircraft The 205A-1, manufactured in 1976, was fitted with a 240-gal. Bambi Bucket adjusted to load 90% of its 2,130-lb. maximum capacity. The aircraft’s two-bladed main rotor and conventional two-bladed tail rotor were powered by a single Ozark Aeroworks T5317B turboshaft engine rated for 1,150 shaft horsepower. The aircraft had flown 23,070 hours as of Sep. 7, and its last inspection was completed four days and 28 flight hours earlier. The operator held FAA certificates to operate under FAR Parts 133 (rotorcraft external load), 135 (commuter and on-demand charter), and 137 (agricultural application). The helicopter at the accident site. (NTSB Photo) The Pilot The 49-year-old commercial pilot was rated for single- and multiengine airplanes, single-engine seaplanes, and gliders in addition to helicopters. Some 2,774 of his 6,100 flight hours had been logged in rotorcraft, including 89 make and model hours divided between training, utility work, and longline operations on wildfires. The remainder of his helicopter time included air tours, utility work, and mountain flying in Bell 206 and Airbus AS350 helicopters. On Jun. 3, 2022, he was issued a US Department of Agriculture/US Department of Interior Interagency Helicopter Pilot Qualification Card authorizing him to fly external load; water/retardant, bucket; helitack/PAX transport; low-level and reconnaissance missions; and flights in mountainous terrain. The Flight The pilot arrived to begin the contract on Monday, Sep 5. On Tuesday, he flew three fuel cycles of about 2.25 hours each, dipping water from Merrill Lake about 2 miles south of the fire. The fourth flight was scrubbed due to a malfunctioning avionics master bus switch. By noon on Sep. 7, the switch had been replaced and the pilot went back to work, making about 10 more drops before returning to the airport in Kelso to refuel. He described the flights and in particular the helicopter’s performance as “unremarkable.” He specifically mentioned that the helicopter was refueled from the same truck used after the previous flight. By the time he took off again, winds had shifted to the north, creating what he later described as “lots of wind currents and ‘weird’ turbulence, but nothing of concern.” To approach into the wind, he followed a racetrack course, turning from a downwind leg over the east side of the lake into a curving right approach at 60 kt. and 350 ft. above ground level before slowing and descending to a 140-ft. hover over the lake’s north end. The first four circuits were likewise uneventful. As he began to raise the bucket after the fifth dip, though, “all hell broke loose.” According to the investigator’s record of a phone interview conducted two days later, He could not specifically hear any engine tone change or “hiccups”, but instead began to experience heavy airframe vibrations. The helicopter was way too “angry” for him to be able to focus on the gauges, and he just seemed to “fall out of the sky”. He had a powerful sense of sinking and an uncommanded yaw to the left. At that point he did not know if it was an engine failure, and he lowered the collective control. He could not specifically deduce what caution lights were illuminated, but was sure the master caution light was on, and then a short time later the low rotor RPM horn. He pulled the collective control about 50-60 ft agl and in an effort to guide the helicopter towards the shoreline he lowered the collective control again and pushed the cyclic forward. He has been flying for almost 30 years, and these were all instinctive reactions. He then got a “ground rush” sense and pulled the collective up. The helicopter landed flat and hard with violence. Everything by that time had stopped, including the engine. He turned off the fuel valve, and the battery, and the helicopter then started rolling to the right. He undid his seatbelt, and removed his helmet to reduce his size, and egressed. He sustained minor injuries and declined to be taken away by ambulance. The helicopter came to rest on its right side in shallow water with the tail boom folded under the cabin and one main-rotor blade bent upward. None of the kayakers, firefighters, or helitack crew at the lake that afternoon witnessed the accident. The Explanation The pilot told investigators that he believed the “engine rolled back … because so many of the panel lights had lit up, and because of the way the helicopter was performing.” Data recorded at five-second intervals by the helicopter’s measured gas temperature (MGT) gauge, however, didn’t suggest an engine failure. Instead, a series of nearly identical cycles of temperature variations between about 550°C and 730°C (1,022°F and 1,346°F) was consistent with the sequence of dips, dumps, and returns to hover during both the previous flight and the preceding circuits of the accident flight. On the final circuit, the MGT rose to 710°C (1,310°F) before abruptly dropping to 150°C (302°F) just 15 seconds before recording ended, consistent with sudden engine stoppage at the moment of water impact. The manufacturer’s detailed examination of the engine found “no indications of fire or uncontainment”; the compressor section could be rotated by hand. Internal damage was likewise consistent with a sudden stoppage, and the chemical composition of debris found inside the engine matched that of the main-rotor blades. A 5 mm–wide fragment of aluminum honeycomb material found at the root of the second-stage turbine rotor appeared to match that used inside the main-rotor blades. There was no evidence of malfunction or failure prior to impact. The pilot’s statement mentioned that “the area was notorious for downslope katabatic wind.” The National Transportation Safety Board (NTSB) developed a High-Resolution Rapid Refresh profiling model that indicated that during the time leading up to the accident, winds shifted from 4 kt. out of the south-southwest to 14 kt. from the northwest. The model didn’t account for any effects of outflow from the fire. These findings led the NTSB to conclude that “rather than losing engine power, the helicopter likely encountered strong downdrafts that caused a rapid descent. The pilot attempted to release the bucket … and while he was ultimately able to do so, until release it was being dragged through the lakebed, thus hindering the helicopter’s maneuverability.” The probable cause of the accident was therefore found to be the helicopter’s encounter with downdrafts during a low-altitude hovering maneuver while dipping for water. The Takeaway The NTSB’s probable-cause report took the somewhat unusual step of commending the pilot’s response to the emergency. Given his perception of a power loss, “his actions under such a circumstance were appropriate.” The board further noted that “water dip operations required that the single-engine helicopter be flown at a low height and speed such that it was operating within the ‘AVOID’ range of its height-velocity envelope. In this range, a safe landing couldn’t be guaranteed following an engine failure. “The pilot was able to demonstrate the presence of mind and helicopter control to maneuver towards the shore with limited altitude and time, and therefore avoid a more significant impact.” The pilot’s success in following the famous principle of legendary combat, test, and air show pilot Bob Hoover to “fly the thing as far into the crash as possible” further corroborates its wisdom. David Jack Kenny is a fixed-wing ATP with commercial privileges for helicopter.
