KINSTON, NC, USA
N23806
Beech 58
After being awake about 20 hrs, the pilot (plt) departed on a positioning flight (flt) at 0217 EDT after two previous flts; although, she said she contemplated 'staying the night in Raleigh because of the fatigue.' She used the aircraft (acft) heater, on the ground & during takeoff. She said that en route, she felt fatigued & contemplated returning to the departure airport, but continued flt. About 5 min before starting a VOR approach (apch), plt turned off the heater. Two times, while being vectored for apch, plt incorrectly read back the direction of turn (left vs right), but other details & radio transmissions were accurate & responsive. The plt said she fell asleep after putting gear down on apch Acft then collided with trees & the ground. Time of accident was about 0250 EDT. Postcrash fire erupted, but plt egressed with injuries that were considered minor. Investigators requested blood specimens to test for carboxyhemoglobin [carbon monoxide (CO) poisoning], but specimens were not provided. (Plt said that due to extreme pain, her doctor opted not to proceed with test.) Pressure testing of heater revealed leaks at a gasket & screw (where fuel nozzle was mounted) & at 2 of 3 cross-over tubes; but these were attributed to impact damage. No evidence was found of any preimpact heater failure or malfunction that would have allowed CO to have entered the cockpit. Two plts used the heater on previous flts, but neither of them noticed any heater problem or symptoms of CO poisoning. About 18 miles west, at 0255 EDT, the ceiling was 300 feet broken. MDA for the approach was 352 feet AGL (440 msl).
HISTORY OF FLIGHT On July 3, 1996, about 0250 eastern daylight time a Beech 58, N23806, registered to a private individual, operated by the ISO Aero Service, Inc., crashed into a corn field northeast of the Kinston Regional Jetport at Stallings Field, Kinston, North Carolina. Weather conditions at the accident site area are unknown and an IFR flight plan was filed for the 14 CFR Part 91 positioning flight. The airplane was substantially damaged and the commercial-rated pilot, the sole occupant sustained minor injuries. The flight originated at 0217 from the Raleigh-Durham International Airport, Raleigh, North Carolina. Before departure the pilot twice phoned the Raleigh Durham Automated Flight Service Station (AFSS), the first call was for a flight to Kinston with a 0200 departure and to file an IFR flight plan. The second call made 14 minutes later, was to obtain an outlook weather briefing for the same flight with a 0600 departure. The pilot stated that before the flight departed she was experiencing fatigue and thought about remaining in Raleigh, but elected to continue. She further stated that after starting the engines, she started the heater which remained on for the takeoff for the 67 nautical mile flight. About 10 minutes after takeoff while in contact with the Seymour Johnson Approach Control, the pilot was advised that the Seymour Johnson Air Force Base (SJAFB) weather was IFR with a broken ceiling at 300 feet and to expect the localizer approach to runway 23. After being advised of the ceiling and visibility at the SJAFB she requested clearance for the VOR approach to runway 23. She further stated that when the flight was about 1/2 way to the destination she felt like returning to Raleigh due to fatigue but elected to continue. The flight was vectored to fly heading 100 degrees but on the reply, the pilot interjected "left" then the heading. The controller then advised the pilot to turn right to a heading of 100 degrees and the pilot then correctly read back the heading and direction of the turn. The pilot again read back an incorrect direction of a turn twice while being vectored for the VOR approach to runway 23. The controller cleared the flight for the VOR approach and advised the pilot to contact the Raleigh AFSS after landing. There was no further radio contact with the controller after the pilot acknowledged the instruction. The pilot reportedly turned off the heater about 5 minutes before beginning the VOR approach. The pilot stated that she fell asleep shortly after extending the landing gear and was awakened after descending through trees and just before impact with the ground. The airplane then spun around and came to rest upright. A fire which was started after the airplane came to rest burned the pilot on her arms and face. The pilot walked from the wreckage to a house and later advised emergency management personnel that she fell asleep during the approach. PERSONNEL INFORMATION The pilot stated that she was not scheduled to fly scheduled flights on July 2nd and she had a maximum of 6 hours sleep when she awoke at 0630 that morning. She arrived at the Kinston Airport at 0800 and flew another company airplane to another airport for maintenance arriving there about 0840 on July 2nd. She remained at the facility, did not sleep, and about 1700 she received a phone call from her company. She was asked if she would fly a different company airplane to Peoria, Illinois, to pick up cargo and deliver it to the Raleigh-Durham International Airport, Raleigh, North Carolina. She stated yes and the accident airplane was flown to her location by another company pilot. The flight to Peoria was uneventful and arrived about 2200. The flight remained on the ground about 30 minutes and the flight departed for Raleigh landing uneventfully where the cargo was offloaded. She did not operate the heater on either flights to Peoria, Illinois, or from there to Raleigh, North Carolina. She also stated that she hand flew the airplane on all flights and encountered thunderstorms on both flights to and from Illinois. On July 1st, the pilot worked in the office from 0800 to 1700 hours at the operator's facility, but flight/duty records provided by the operator indicated that she was off duty. On June 30th she worked a duty day of 6 hours from 1030 to 1630 but she was not sure what time she woke up that day or what time she went to bed the night before. On June 29th, she worked a duty day of 6 hours from 0930 to 1530 and was again not sure what time she woke or what time she went to bed the night before. On June 28th, she worked a duty day of 1 hour starting at 0630 and she reported awaking no later than 0600 and was not sure of the time she went to bed the night before. AIRCRAFT INFORMATION Review of the aircraft logbook revealed that the heater was last inspected as required by airworthiness directive (AD 82-07-03) on July 13, 1995, at a heater Hobbs time of 663 hours. The AD for the installed heater requires in part periodic inspections at intervals not to exceed 100 heater-hours time-in-service or 24 months, whichever occurs first. The heater Hobbs indicated post accident 753.9. METEOROLOGICAL INFORMATION Weather information at the Kinston Airport at the time of the accident was not available. A weather observation taken at 0255 from the Seymour Johnson Air Force Base which was located about 18 nautical miles and 275 degrees from the crash site indicated that a broken ceiling existed at 300 feet and the visibility was 4 miles. Review of the instrument approach procedure indicates that the minimum descent altitude is 352 feet above ground level or 440 feet mean sea level. COMMUNICATIONS The pilot was in contact with the Seymour Johnson AFB Radar Approach Control (RAPCON) facility and a transcript is an attachment to this report. WRECKAGE AND IMPACT INFORMATION Examination of the accident site was performed by an FAA inspector who reported that the left engine was separated and the left wing was separated just outboard of the engine nacelle. Fire damage to the right wing was noted. The airplane was found upright in a corn field and the landing gear had been determined to be extended and the flaps retracted at the impact. The cabin air vent was in the "on" position and the heater was in the "off" position. The FAA inspector stated that the airplane crashed in line with the extended centerline of the runway and the crash site was located about 1.5 nautical miles from the runway threshold. The exhaust pipe of the heater was determined to be properly installed with no blockage noted and the heater and associated components were removed for further testing. See the Tests and Research Section of this report. MEDICAL AND PATHOLOGICAL On the morning after the accident, the FAA inspector who performed the on-scene examination of the wreckage called the laboratory at the hospital where the pilot was initially taken and verbally requested that a test be performed to determine the presence in the blood of carbon monoxide. The FAA inspector visited the hospital that evening and again requested that carbon monoxide testing be performed. The hospital laboratory did not test for carbon monoxide and the sample was not retained for testing. The pilot did not report any strange odors nor did she report experiencing a headache during or after operating the heater during the accident flight segment. She did report experiencing nausea, feeling sick to her stomach, blurred vision, and confusion when the controller advised her that the flight was observed on radar to be left of course when the CDI was beginning to center. TESTS AND RESEARCH Testing of the combustion tube assembly was initially performed twice at the operator's facility under the control of the FAA inspector who performed the on-scene examination. The first and second tests revealed that the pressure in the combustion chamber dropped below 1.0 psig at 45.83 and 45.01 seconds respectively. The heater maintenance and overhaul manual indicates that after 45 seconds the pressure in the combustion chamber must exceed 1.0 psig. If the pressure drops below 1.0 psig before 45 seconds, that indicates a leak is present either in the combustion chamber or around the seals. Leakage was noted around the gasket and attach screw of the valve assembly. The heater assembly was then sent to the manufacturer's facility for further examination. Examination of the heater assembly revealed that the outer shroud exhibited impact damage and the fuel inlet tube was bent. Additionally, the combustion tube outer jacket assembly and combustion tube exhibited impact damage. Pressure decay tests of the combustion tube assembly revealed that the pressure decreased consistently from the test 6.0 psig to 0 psig in about 10 seconds with an average of 8 seconds. The combustion tube was pressurized and a soap and water solution was brushed over the combustion tube. Again a leak which was previously noted occurred at the fuel feed retaining screws and at the sealant material between the fuel feed and the nozzle holder. Also, a leak was noted at two of the three crossover tubes which provide an escape path for the exhaust from the combustion chamber. There was no visible evidence of burn through, cracks, or holes in the combustion chamber, or the liner which covers the combustion chamber or of the outer shroud. Further testing of the combustion air blower/motor, ventilation blower/motor, ignition system, fuel solenoid valve and spray nozzle, combustion air pressure differential switch, or the overheat switch revealed no evidence of preimpact failure or malfunction. A discrepancy to the overheat switch was noted but the switch was operational. Further examination of the crossover tubes with a 10 power magnifying glass revealed no evidence of cracks or holes. Zyglow testing of the two crossover tubes that exhibited evidence of leakage indicated penetrant seepage but examination of the inside of the tubes revealed no evidence of cracks or holes. According to the heater manufacturer, the sealant between the fuel feed and the nozzle holder was improper. Research performed by an engineer with the heater manufacturer revealed that the pressure on the ventilating air side is greater than the combustion side, and with normal combustion and a hole or leak, ventilation air would be forced into the combustion and out the exhaust. Further tests with the end of the combustion tube completely removed allowing all products of combustion into the airstream and satisfactory combustion revealed a percent volume of carbonmonoxide of .0002 to .00027. This is less than the maximum permissible percent by volume allowed by the U.S. Army (.005), Navy (.010), and the SAE (.005). Additionally, by heater design the fuel/air ratio is .060 which reduces the carbonmonoxide content of the exhaust gases. Further research indicates that to allow a 10 percent by volume of carbonmonoxide in the exhaust gases will require a hole "tremendously" larger than a number of hairline cracks or pin holes. Review of literature concerning aircrew fatigue and circadian rhythm revealed that in part maximum sleepiness will occur between 0300 (about 10 minutes after the accident) and 0500. Additionally, flight testing involving experienced military pilots indicate that the maximum degradation in performance occurred about 0300. The owner of the accident airplane who had flown it with his wife on board in the middle of June on two separate flights on two consecutive days reported operating the heater continuously for 1 hour on each of the flights. He reported no health problems to himself or his wife. Another company pilot who had flown the accident airplane on several flights on June 27, 1996, reported operating the heater continuously for a total of 1 hour 15 minutes on one of the flights and 45 minutes continuously on another of the flights. He also reported no health problems or specifically no carbon monoxide poisoning. Review of literature provided by the Director of the FAA Toxicology and Accident Research Laboratory in Oklahoma City, Oklahoma, revealed that at 10-20 percent COHB saturation, signs and symptoms include tightness across the forehaed, possibly slight headache. At 20-30 percent the signs and symptoms include headache, and throbbing in the temples, easily fatigued, and possible dizziness. As stated earlier the pilot did not report experiencing a headache. ADDITIONAL INFORMATION The wreckage minus the retained heater was released to Mr. Reuben Edwards, the Director of Maintenance on July 26, 1996. The retained heater components were again released to Mr. Edwards on March 12, 1997.
failure of the pilot to maintain minimum descent altitude (MDA) during approach because of fatigue.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
