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N416PH accident description

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Tail numberN416PH
Accident dateJune 08, 2008
Aircraft typeBell 407
LocationHuntsville, TX
Near 30.630834 N, -95.563889 W
Additional details: None

NTSB description

This report was updated on August 14, 2009.

On June 8, 2008, at 0248 central daylight time, a Bell 407 emergency medical services (EMS) helicopter, N416PH, owned by PHI, Inc., and operated by PHI as Med 12, was destroyed when it impacted a heavily forested area in the Sam Houston National Forest, south of Huntsville, Texas. Dark night visual meteorological conditions prevailed at the time of the accident. The air ambulance flight was being operated under the provisions of Title 14 Code of Federal Regulations Part 135 on a company visual flight rules (VFR) flight plan. The pilot, flight nurse, flight paramedic, and passenger were fatally injured. The flight had departed the Huntsville Memorial Hospital Heliport (KTE03) at 0246, after picking up a patient, and was en route to the John S. Dunn Helistop (K38TE) at the Herman Memorial Hospital, Houston, Texas.

The flight to K38TE was 68.7 nautical miles on a magnetic bearing of 168.1 degrees. The accident helicopter was equipped with a Global Positioning System (GPS) flight tracking system referred to as "Outerlink." According to the Outerlink system, the helicopter powered up for flight at 0244:11 and departed the hospital at 0246:56. The last coordinates recorded by the Outerlink system were recorded at 0247 at an altitude of 1,016 feet mean sea level (approximately 600 feet above ground level (agl)), while traveling at a groundspeed of 106 knots. The calculated direction of flight was 170 degrees. Med 12's first position report was due at 0300.

According to an emergency room clerk at Memorial Hospital - The Woodlands, the accident flight contacted him over the radio to place his hospital on standby for the patient. A female provided a patient assessment and during the radio call a male voice could be heard. It could not be distinguished what the male voice was saying. The radio call became unreadable and did "not come back." Memorial Hospital - The Woodlands Heliport (K26TS) was located 36.5 miles from KTE03 on a magnetic bearing of 166.8 degrees. He could not recall the exact time.

At 0259, one minute prior to Med 12's required position report, the Air Force Rescue Coordination Center contacted the PHI Communications Center in Lafayette, Louisiana, regarding an emergency locator transmitter signal they were receiving, registered to N416PH (Med 12). Search and rescue efforts were initiated immediately and multiple attempts to communicate with the missing helicopter were made.

The wreckage was located by aerial search and rescue teams at 0830, about 2.5 miles southwest of the last known coordinates, with the aid of the 406 MHz emergency locator transmitter (ELT).

The National Transportation Safety Board (Safety Board) Investigator in Charge (IIC) interviewed several witnesses. These witnesses were located to the north of the impact location. According to one witness, between 0245 and 0300 he heard a helicopter fly over his home with "high pitch" sounds. He stated that helicopters fly over his house all the time; however, this one woke him up, as it was loud. He assumed that the helicopter was flying relatively low, as it was vibrating his house.

PERSONNEL INFORMATION

The pilot, age 63, held an airline transport pilot certificate with a rotorcraft helicopter rating last issued on November 21, 1991. He was issued a second class airman medical certificate on March 13, 2008. The certificate contained the limitation "holder shall wear corrective lenses."

The pilot was hired by PHI Inc, in January 1976. According to PHI's records, the pilot had logged no less than 20,537 hours flight time in rotorcraft; 200 of which was in the make and model of the accident helicopter, and no less than 224 hours at night. The pilot had been flying EMS operations for PHI for 18 months and had accumulated 205.5 hours in EMS operations; 36 hours of which were in the past 90 days and 5.4 hours at night. Their records reflect that the pilot had accepted 36 night flights within the previous 18 months.

The pilot's airman competency/proficiency check for CFR 135.293 (Initial and recurrent pilot testing), and 135.299 (Pilot in command: Line checks: Routes and Airports) was completed with a satisfactory rating in all tested areas on November 17, 2007. The flight check was conducted in a Bell 407 helicopter in daylight conditions. Transition training to EMS operations was performed in November of 2006. At this time, night operations training was conducted.

According to PHI's records, the pilot had been on the day shift (0700 to 1900) from May 15th through the 28th, 2008. He started duty for the night shift (1900 to 0700) on May 30, 2008, had two days off, and then continued with the night shift until June 8, 2008. Following his rotation to the night shift, the pilot had logged one hour and 27 minutes of flight time on the shift prior to the accident. In addition he logged 25 minutes on the night of the accident, while positioning the helicopter from his base to the hospital.

The pilot had not been trained for the use of NVIS. According to PHI's director of safety, there were no safety issues or occurrences that involved the pilot, prior to the accident.

AIRCRAFT INFORMATION

The accident helicopter, a Bell 407 (serial number 53276), was manufactured in 1998. It was registered with the FAA on a standard airworthiness certificate for normal operations. The helicopter was powered by a Rolls-Royce turbo shaft C-47B engine rated at 650 shaft horsepower.

The helicopter was registered to and operated by PHI Inc. of Lafayette, Louisiana, and was maintained under an Approved Inspection Program (AAIP), by PHI out of the Bryan, Texas, base. A review of the maintenance records indicated that an AAIP, event two inspection had been completed on April 16, 2008, at an airframe total time of 6,141 hours and 8 minutes. The helicopter had flown approximately 92 hours and 11 minutes between the last inspection and the accident and had a total airframe time of 6,233 hours and 19 minutes.

The helicopter was equipped with the Aviation Night Vision Imaging System (cockpit lighting system that is compatible with night vision goggles) in April 2008 and had a Free Flight radar altimeter installed. The helicopter was not equipped with Helicopter Terrain Awareness Warning System (HTAWS).

METEOROLOGICAL CONDITIONS

The Safety Board IIC interviewed the pilot for Memorial Herman Life Flight that had accepted the same patient transfer flight the morning of the accident. According to this pilot, the weather en route to Huntsville, Texas, was VFR. Prior to his flight, the lowest weather reported for his entire flight was at Huntsville and at the time of the report, the weather was "better than 2,000 [ceiling] and ten [miles visibility]."

He departed Memorial Herman at 0106 and flew GPS direct towards Huntsville. There were no traffic or weather concerns at the time of his departure. While en route, approximately 5 miles south of the hospital (KTE03), at 1,400 feet he encountered "wispy clouds." He descended to 1,200 feet and encountered more clouds, continued to descend, to 1,000 feet, encountered more clouds, and finally descended to 800 feet when the visibility decreased rapidly. He stated that he could see to the east but had lost his "surface light reference." He turned immediately to the right, towards the "freeway system" and was immediately back in good weather. He stated that the low clouds and visibility were "pretty sudden and pretty dramatic." The flight was aborted after encountering the weather. Upon his return, he entered this information into a pilot website "weatherturndown.com."

The Terminal Aerodrome Forecast (TAF) for KUTS forecasted winds at 140 degrees at seven knots, visibility greater than six miles, and broken clouds at 1,500 feet for the time period just prior to the accident. The area forecast for southern Texas forecasted cloud cover at 2,000 feet above ground level. The outlook was for visual flight rules conditions. Airman's Meteorological Information (AIRMET) for instrument flight rules (IFR), turbulence, and icing had not been issued for the accident helicopter's route of flight. Significant IFR, icing, or turbulent conditions were not expected outside of convective activity.

The closest official weather observation station was Huntsville Municipal Airport (KUTS), Huntsville, Texas, located six nautical miles (nm) north of the accident site. The elevation of the weather observation station was 363 feet msl. The routine aviation weather report (METAR) for KUTS, issued at 0235, reported, winds variable at six knots; visibility ten miles; sky condition scattered 1,200 feet; temperature 26 degrees Celsius (C); dewpoint 23 degrees C; altimeter 29.98 inches.

The METAR for Lone Star Executive Airport (KCXO), Conroe, Texas,(located 18 nautical miles southeast of the accident site) issued at 0240 reported winds, 160 degrees at six knots; visibility ten miles; sky condition, few clouds at 1,700 feet; temperature, 26 degrees C; dewpoint, 23 degrees C; altimeter 29.97 inches.

According to the United States Naval Observatory, Astronomical Applications Department Sun and Moon Data, the moon rose at 1023 on the preceding day and set at 0015 the day of the accident. The moon was waxing crescent with 30 percent of the moon’s visible disk illuminated.

COMMUNICATIONS

Recordings of telephone conversations involving PHI dispatch were provided to the Safety Board IIC for the investigation. These recordings were transcribed, revealing the following:

Approximately 0120 PHI dispatch was contacted by Huntsville Memorial Hospital emergency room with a patient transfer request. The caller stated that they had initially requested "Herman" but the flight was "aborted" due to "some kind of cloud overhead, a patch of fog." The caller asked if they had a helicopter available and if a weather check could be performed.

The pilot was notified of the flight and performed a weather check for the route of flight. After his weather check, he contacted PHI's Enhanced Operational Control Center (EOCC) to discuss his weather observations and the previous "turn down." Both the pilot and EOCC supervisor were observing "ten miles" visibility and ceilings acceptable for the flight. It was not understood by the pilot or the supervisor as to the reason the other operator "turned down" the flight. The pilot contacted EOCC a second time to discuss that the previous flight had been "turned down" due to "fog." The pilot and the EOCC supervisor discussed further weather observations with the same conclusion, that the restriction to visibility reported by the previous flight was not observed by any official weather reporting station.

The pilot contacted the EOCC supervisor a third time after arriving at Huntsville. The pilot reported that the flight was without problems and the weather was as forecast. Further weather observations were discussed between the pilot and EOCC supervisor with the same conclusions, that it was unknown where the visibility restriction experienced by the previous flight was encountered.

FLIGHT RECORDERS

The helicopter was equipped with a full authority digital engine control unit (FADEC). The unit had separated from the helicopter and was located approximately 10 to 15 feet west of the main wreckage. The unit was shipped to Indianapolis, Indiana, for data extraction. On June 10, 2008, under the auspices of the Federal Aviation Administration (FAA), a FADEC download was conducted.

Two full lines of data and one partial line of data were recovered. The first line recorded a torque exceedance at 110 percent. The second line recorded an NR (main rotor) droop at 90 percent. According to Rolls Royce, this is consistent with a sudden stoppage. The small amount of data recovered was due to the electrical power loss during the impact sequence.

WRECKAGE AND IMPACT INFORMATION

The accident site was located in densely forested terrain. Lake Conroe, 16 miles long and 10 miles at its widest point, was located six miles to the southwest of the main wreckage. Multiple bodies of water, including Lake Raven, Sunset Lake, Elkins Lake, and Club Lake, were all located within 2 miles of the initial impact point. The accident site was at a terrain elevation of 344 feet msl and the helicopter impacted on a magnetic heading of 180 degrees. The initial impact point was identified as several trees, 80 to 100 feet in height at a terrain elevation of 354 feet mean sea level (msl). The tops of multiple trees and many branches exhibited separation features consistent with being torn and cut. Tree and branch width varied from less than one inch to over 13 inches in diameter.

The green main rotor blade was located 156 feet southeast of the initial impact point. Pieces of fragmented honeycomb and Plexiglas, the transmission cowling, and a cabin door were all located in the debris path that extended from the initial impact towards the main wreckage. A tree, measuring 13 inches in diameter at the point of separation, was broken approximately 30 feet from the tree base in the direction of impact. This tree was located 100 feet north of the forward tail boom.

The transmission and mast were located 511 feet south of the initial impact point. The aft portion of the tail boom, including the tail rotor and tail rotor gearbox, was located 50 feet west of the transmission and mast assembly. The forward portion of the tail boom, including the right side horizontal stabilizer, a portion of the tail rotor drive shaft, left side horizontal stabilizer, and right side auxiliary fin separated from the fuselage and came to rest 578 feet south of the initial impact point.

The aft portion of the fuselage, to include the aft cabin, and engine assembly, was located 22 feet south of the tail boom. The center portion of fuselage to include the center portion of the cabin, a section of the landing skid, and the blue main rotor blade, came to rest inverted 22 feet south from the aft portion of the fuselage. The forward portion of fuselage to include the cockpit and instrument panel, and a portion of the landing skid, came to rest inverted ten feet south of the center fuselage section and 629 feet south of the initial impact point. The smell of fuel was dominant near the main wreckage.

MEDICAL AND PATHOLOGICAL INFORMATION

The autopsy was performed on the pilot by the Southwestern Institute of Forensic Sciences, Dallas, Texas, on June 9, 2008, as authorized by the Justice of the Peace, Precinct 3, Walker County, Texas. The autopsy revealed the cause of death as "blunt force injuries."

During the autopsy, specimens were collected for toxicological testing to be performed by the FAA's Civil Aerospace Medical Institute, Oklahoma City, Oklahoma (CAMI Reference #200800113001). Tests for carbon monoxide, cyanide, and ethanol were negative. Diphenhydramine was detected in the urine but was not detected in the blood. Diphenhydramine can be used as an antihistamine, sleep aid, or cough suppressant.

TESTS AND RESEARCH

The wreckage was recovered on June 9, 2008, and relocated to a storage facility in Lancaster, Texas, for further examination. The wreckage was examined by investigators from the National Transportation Safety Board, Federal Aviation Administration, Bell Helicopter, Rolls Royce, and representatives from PHI Inc. on June 10th and 11th.

The wreckage was laid out in a partial mock-up manner. The left forward portion of the fuselage was crushed aft and down. The upper right side of the cabin structure, just aft of the pilot's seat, was crushed down and aft. The roof of the fuselage separated and was fragmented. The instrument panel was crushed and many instruments destroyed. The Kollsman Window was set at 29.96 inches.

The aft portion of the tail boom included the vertical fin, gearbox, and tail rotor and exhibited crushed and torn metal, near the stabilizer, consistent with a main rotor strike. The third driveshaft on the tail boom had wood embedded in the fractured end. The shaft exhibited circumferential scoring two inches from the point of separation. Tail rotor controls were continuous from the point of tail boom separation aft to the tail rotor with both the driveshaft and pitch control. The target blade e

(c) 2009-2011 Lee C. Baker. For informational purposes only.