Beaumont, TX, USA
N9273T
Bell OH-58C
A single-engine public use helicopter was destroyed when it impacted water while maneuvering over a lake at night during a search mission. The 2,475-hour commercial pilot reported that he had set the altimeter to the current barometric pressure setting of 29.75 inches of Mercury prior to departure. Then, he and the pilot-rated passenger departed and made several passes over the lake at 500 feet, then descended to 300 feet for better visual reference of an object on the water. The crew still had difficulty identifying the object and the pilot descended to 200 feet. The pilot reported that there was absolutely no reference to the horizon, so he told the passenger that he would be "on the instruments." As the pilot made a right hand turn, he said the altimeter indicated a slow descent from 200 feet, so he pulled back slightly on the cyclic and increased collective pitch to start a smooth, climbing right turn. As the pilot did so, the passenger shouted, "look out!" The pilot pulled the cyclic back sharply and looked out the windscreen. The pilot thought that he was about to strike a tower because the altimeter indicated an altitude between 150 and 175 feet. The pilot then saw a "black wall" through the windscreen and they collided with the water. Examination of the altimeter revealed that it was not impact damaged, but did exhibit water and corrosion damage. It displayed a barometric pressure setting of 29.66 inches of Mercury and an altitude of approximately 110 feet. Due to corrosion, the unit could not be bench tested. The face of the instrument was removed, and excessive corrosion was observed inside the unit and around the gears. The barrel shaft (turn knob) was locked, but it was engaged to the barrel. The number-wheels were also intact and engaged. According to the aircraft checklist, the altimeter was to be set and checked by the pilot prior to take-off.
HISTORY OF FLIGHTOn September 15, 2004, approximately 2237 central daylight time, a Bell OH-58C single-engine helicopter, N9273T, was destroyed when it impacted water while maneuvering over Sabine Lake near Beaumont, Texas. The commercial pilot sustained minor injuries and the commercial pilot-rated passenger was fatally injured. The helicopter was registered to and operated by the Jefferson County Sheriff's Department. The helicopter departed from the Southeast Texas Regional Airport (BPT) near Beaumont, Texas, approximately 2210, in response to a reported boat fire. Night visual meteorological conditions prevailed and no flight plan was filed for the public use flight conducted under 14 Code of Federal Regulations Part 91. In a written statement, the pilot reported that prior to departing from Southeast Texas Regional Airport, he and his pilot-rated passenger obtained the current automated weather observing system (AWOS) information, and set the altimeter accordingly to a barometric pressure setting of 29.75 inches of Mercury. The pilot flew from the right seat and the passenger sat in the left seat. Upon arrival to the site of the reported boat fire, the pilot and passenger did not observe any fire coming from the lake. They assumed that the vessel might have sunk, so they began to search for survivors or anything that may have come from the vessel. The Coast Guard suggested that they start their search at the north end of Sabine Lake and work toward the Coast Guard vessels. The pilot and passenger complied with their request and started a standard grid search from "the east end of the Thousand Foot Cut to the western tip of Pleasure Island." After several passes, the pilot saw something on the water that reflected light on his side of the helicopter. He pointed the object out to the pilot-rated passenger, but the passenger could not identify it, so they descended to 300 feet. The pilot-rated passenger could still not identify the object, so he agreed with the pilot that they should descend to 200 feet. The pilot reported that there was absolutely no reference to the horizon, so he told the passenger that he would be "on the instruments." As the pilot continued in a right hand orbit, he said the altimeter indicated a slow descent from 200 feet. In response to this indication, the pilot "pulled back slightly on the cyclic and increased collective pitch to start a smooth, climbing right turn." As the pilot did so, the pilot-rated passenger screamed, "look out!" The pilot pulled the cyclic back sharply and looked out the windscreen. The pilot thought that they might be about to strike a tower or other tall object because that altimeter indicated an altitude between 150 and 175 feet. The pilot saw a "black wall" coming at them through the windscreen. When they collided, the pilot felt wet, so he knew that they were under water. The pilot managed to release himself from his safety restraints and float to the surface. The pilot shouted for the pilot-rated passenger, but heard no reply. The pilot swam around the wreckage, searching for his passenger, but could not find him. The pilot was rescued from the lake around 0245 the following morning. PERSONNEL INFORMATIONThe 2,475-hour pilot held a commercial pilot certificate for airplane single-engine land, airplane multi-engine land, rotorcraft-helicopter, and instrument airplane. He was also a certified flight instructor with ratings for airplane single-engine land, airplane multi-engine land, rotorcraft-helicopter, and instrument airplane. His most recent Federal Aviation Administration (FAA) first class medical was issued on August 9, 2004. The 2,725-hour pilot-rated passenger held a commercial pilot certificate with ratings for airplane single-engine land, airplane multi-engine land, rotorcraft-helicopter, and instrument airplane. His most recent Federal Aviation Administration (FAA) first class medical was issued on February 26, 2003, and was only valid when accompanied by another qualified pilot. AIRCRAFT INFORMATIONThe Bell OH-58C helicopter was powered by an Allison 250-C20 turbo-shaft, 400-shaft horsepower engine. The aircraft underwent it's last annual inspection on August 30, 2002, at a total time of 4,063.4 hours. The helicopter was registered to the Jefferson County Sheriff's Department as a public use aircraft; therefore, an airworthiness certificate was not required. METEOROLOGICAL INFORMATIONAt 2153, the automated weather observing system at Southeast Texas Regional Airport, located approximately 10 nautical miles west of the accident site, reported wind from 020 degrees at 7 knots, 10 statute miles of visibility, sky clear, temperature 82 degrees Fahrenheit, dew point 66 degrees Fahrenheit, and a barometric pressure setting of 29.74 inches of Mercury. The field elevation was 15 feet msl. According to the U.S. Naval Observatory in Washington, D.C., the fraction of the moon that was illuminated at the time of the accident was 1/100. AIRPORT INFORMATIONThe Bell OH-58C helicopter was powered by an Allison 250-C20 turbo-shaft, 400-shaft horsepower engine. The aircraft underwent it's last annual inspection on August 30, 2002, at a total time of 4,063.4 hours. The helicopter was registered to the Jefferson County Sheriff's Department as a public use aircraft; therefore, an airworthiness certificate was not required. ADDITIONAL INFORMATIONA majority of the helicopter was recovered, including the cockpit and instrument panel. The altimeter was removed and sent to the Safety Board for examination. External examination of the unit revealed that it was not impact damaged, but did exhibit water and corrosion damage. The altimeter displayed a barometric pressure setting of 29.66 inches of Mercury in the Kollsman window and an altitude of approximately 110 feet msl. Due to corrosion, the unit could not be bench tested. The face of the instrument was removed, and excessive corrosion was observed inside the unit and around the gears. The barrel shaft (turn knob) was locked, but it was engaged to the barrel. The number wheels were also intact and engaged. According to the altimeter pressure scale, if the unit was properly calibrated, it would have indicated an altitude of approximately 235 feet msl if it was set to 29.66 inches of Mercury. If the unit was set to 29.75 inches of Mercury, the altimeter would have indicated an altitude of approximately 159 feet msl. The altimeter had its last 24-month inspection on January 15, 2003. A review of the airplane's discrepancy log revealed that no recent maintenance was conducted on the altimeter. According to the OH-58C Normal Procedures checklist, page 8-8, section 8-18 (Engine Run-up), instruction 6 (Flight Instruments) part b, stated: Altimeter-set and check. A review of the Jefferson County Sheriff's Office and Beaumont Police Department Aviation Manual, the normal operating altitude for Aviation Unit helicopters was 500 to 800 feet above ground level during the day and 700 to 1,000 feet above ground level at night. It sated, "Most operations will be conducted between 500 and 1,000 feet above the ground, however, the need may arise to operate at a lower level to facilitate the mission. When such operation is required, extreme care must be exercised with respect to towers, power lines, other tall obstructions and the maintenance of sufficient altitude to permit a safe emergency landing in conformance with Federal Aviation Regulation (FAR) part 91.119. Pilots shall operated all Aviation Unit aircraft in accordance with the approved aircraft flight manual, Federal Aviation Regulations, and Aviation Unit directives." MEDICAL AND PATHOLOGICAL INFORMATIONToxicological tests were performed on both the pilot and pilot-rated passenger by the FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma. Test results for the pilot-rated passenger revealed that 38.02 (ug/ml, ug/g) of Acetaminophen were detected in the urine. Chlorpheniramine was detected in the blood and present in the urine sample. Diphenhydramine was not detected in the blood, but was present in the urine.
**This probable cause was modified on 2/22/2016. Please see the public docket for this accident for additional details.** The pilot's failure to maintain a safe altitude, resulting in collision with the water. A factor was the dark night.
Source: NTSB Aviation Accident Database
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