Tooele, UT, USA
N9381W
PIPER PA-28-235
The airplane broke apart in flight while the pilot was maneuvering at cruise altitude. A witness in another airplane, who was 4 to 5 miles in trail of the accident flight at the same altitude, clearly saw the strobe lights of the accident airplane in front of him. The witness climbed to 9,500 feet and encountered what he described as cumulonimbus clouds and light icing. He stated that the temperature was 32-34 degrees Fahrenheit. He descended to 7,500 feet where he encountered severe turbulence, which caused him to hit his head violently against the cabin ceiling. He observed that he was below the accident airplane, and estimated that it was at 8,500 feet. He then lost sight of it. Radar data indicated that the accident flight turned left, and then began a descending right turn. The airplane broke apart during the turn. The fracture surfaces indicated a positive overload condition on all separated wing and tail components, with significant permanent set deformation of major structural elements in the wings and tail observed. A metabolite of diazepam (a prescription anti-anxiety medication commonly known by the trade name Valium), was found in the pilot's kidney and liver on toxicology testing. The pilot had a prior history of anxiety and depression that was treated with medication, though he had reportedly not received any recent medical treatment or medication. No blood or urine was available for analysis, so it is not possible to estimate when in the previous days or weeks that diazepam might have most recently been used or to determine the relevance, if any, of the medication or the condition for which it was used.
HISTORY OF FLIGHT On March 7, 2007, about 2135 mountain standard time, a Piper PA-28-235, N9381W, broke apart in flight near Tooele, Utah. Cherokee Flyers, Inc., was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certified flight instructor (CFI) pilot and two passengers were killed; the airplane was destroyed. The cross-country personal flight departed Wendover, Utah, about 2110 with a planned destination of Salt Lake City, Utah. Visual meteorological conditions prevailed, and no flight plan had been filed. A witness in another airplane was in the landing pattern at Wendover with his CFI, and heard the accident pilot announce his departure. The witness conversed with him, and observed him take off and depart toward Salt Lake City. He also departed the pattern en route to Salt Lake City, and was 4-5 miles in trail. He observed the strobe lights of the accident airplane in front of him. He climbed to 9,500 feet, but encountered what he described as cumulonimbus clouds and light icing. He stated that the temperature was 32-34 degrees Fahrenheit. He descended to 7,500 feet where he encountered severe turbulence, which caused him to hit his head violently against the cabin ceiling. He observed that he was below the accident airplane, and estimated that it was at 8,500 feet. He lost sight of it in the first mountain range east of Wendover, which he thought were the Cash Mountains. He radioed the other pilot for a weather check, but received no reply. He made several more unsuccessful attempts to establish contact. When the pilot and passengers did not return as scheduled, the family notified the FAA, who issued an alert notice (ALNOT) about 0130. The Civil air Patrol (CAP) found the wreckage about 0700. The National Transportation Safety Board investigator-in-charge (IIC) reviewed recorded radar data. At 2117, there was a target east of Wendover with a secondary 1200 (VFR) beacon code at a mode C reported altitude of 6,300 feet msl. The data recorded a target about every 10 seconds. The target climbed on an easterly course until 2133:47 when it began a left turn to the north for 30 seconds. The next target was to the right toward the east, and this was the last target with a beacon code. It occurred at 2134:37 at an altitude of 8,200 feet. The next target at 2134:47, which was the last one recorded, was a primary, and it was to the south. Its coordinates were 40 degrees 46 minutes 51 seconds north latitude 113 degrees 5 minutes 9 seconds west longitude. The main wreckage was at 40 degrees 46 minutes 42 seconds north latitude 113 degrees 5 minutes 2 seconds west longitude. The accident site elevation was 4,310 feet. PERSONNEL INFORMATION A review of Federal Aviation Administration (FAA) airman records revealed that the 39-year-old pilot held a commercial pilot certificate with ratings for airplane single-engine land, multiengine land, and instrument airplane. The pilot held a certified flight instructor (CFI) certificate with a rating for airplane single-engine land, multiengine land. The pilot held a first-class medical certificate issued on December 28, 2006. It had no limitations or waivers. No personal flight records were located for the pilot. The IIC obtained the aeronautical experience listed in this report from a review of the FAA airmen medical records on file in the Airman and Medical Records Center located in Oklahoma City. The pilot reported on his medical application that he had a total time of 430 hours. A CFI reported that he flew with the pilot in the accident airplane on four occasions during October 2006 for a total of 5.2 hours, and found him competent in the airplane. AIRCRAFT INFORMATION The airplane was a Piper PA-28-235, serial number 28-11074. The operator reported that the airplane had a total airframe time of 5,269.7 hours at the last annual inspection, which occurred on June 1, 2006. The engine was a Textron Lycoming O-540-B4B5, serial number RL-14619-40A. Total time recorded on the engine at the last annual inspection was 1,157 hours. METEOROLOGICAL CONDITIONS The closest official weather observation station was Salt Lake City (KSLC), which was 50 nautical miles (nm) east of the accident site. The elevation of the weather observation station was 4,227 feet msl. An aviation routine weather report (METAR) was issued at 2056 MST. It stated: winds from 140 degrees at 7 knots; visibility 10 miles; skies 11,000 feet broken; temperature 11/51 degrees Celsius/Fahrenheit; dew point -1/30 degrees Celsius/Fahrenheit; altimeter 29.99 inches of mercury. WRECKAGE AND IMPACT INFORMATION On site wreckage examination noted the debris path covered about 0.6 mile on a heading of 157 degrees. The first identified major piece of wreckage (FIW) was the inverted right horizontal stabilator. About 50 feet further was the inverted right wing tip, which contained an auxiliary fuel tank. About 175 feet from the FIW was the upright left horizontal stabilator. The vertical stabilizer with the top 1/3 of the rudder attached was at 740 feet. The inverted left wing with the landing gear attached was at 1,180 feet. The rudder fairing with the counterweight attached was at 1,600 feet. The remainder of the inverted right wing was at 1,800 feet; the landing gear separated, but remained attached by the brake line. The inverted engine, propeller, and fuselage (with the lower 2/3 of the rudder attached) were the last major pieces of wreckage at 2,600 feet. This wreckage was on a heading of 045 degrees. MEDICAL AND PATHOLOGICAL INFORMATION The Utah Office of the Medical Examiner completed an autopsy, and determined that the cause of death was multiple blunt force injuries. The FAA Forensic Toxicology Research Team, Oklahoma City, Oklahoma, performed toxicological testing of specimens of the pilot. Analysis of the specimens for the pilot contained no findings for volatiles in liver or muscle. Tests for carbon monoxide and cyanide were not performed. The report contained the following findings for tested drugs: 0.1 (ug/ml, ug/g) nordiazepam detected in liver, and 0.065 (ug/ml, ug/g) nordiazepam detected in kidney. The medical records maintained on the pilot by the FAA Aerospace Medical Certification Division were reviewed. An application for 3rd class Airman Medical and Student Pilot Certificate dated October 12, 1999, indicated that no medications were currently being used. The application did indicate that the pilot had been treated for anxiety and depression, noting that Xanax [alprazoloam] and Zoloft [sertraline] were prescribed in October of 1998, but that the pilot was off the medications at the time of the application. A physician’s letter to the FAA noted, in part, that the pilot used the prescriptions only temporarily, did not have chronic depression or other symptoms, and was off the medications as of July, 1999. In January, 2000, the Manager of the FAA Aeromedical Certification Division notified the pilot that he was eligible for a first-class medical certificate. It stated that, because of his history of anxiety, operation of aircraft was prohibited at any time new symptoms or adverse changes occurred, or any time medication and/or treatment were required. A pre-operative examination for LASIK eye surgery in December 2003 noted, in part, that the pilot took Lortab [hydrocodone/acetaminophen] once in a while for headaches. The pilot's most recent application for 3rd class Airman Medical Certificate dated December 28, 2006, indicated that the pilot was not currently taking any medications. It also indicated no in response to all items under "Medical History," including specifically "Frequent or severe headaches" and "Mental disorders of any sort; depression, anxiety, etc." The application also noted there were no visits to health professional within the previous 3 years. The pilot's spouse indicated that she was not aware of any current medical conditions or any medication use by the pilot. TESTS AND RESEARCH Airframe Both wings separated at the root area. The lower left wing separated at the outboard attachment boltholes in a jagged pattern; the spar bent upward. The upper left wing remained attached to a section of the carry through spar by the wing attachment bolts; this section of the carry through spar separated from the center fuselage section. It exhibited about 30 degrees of permanent deformation in an upward direction at the separation point. The wing exhibited a downward permanent deformation; it buckled in the vicinity of the outboard flap hinge at wing station 106.19. The bottom skin in this area separated in a jagged manner. The flap remained attached to the wing. The lower right wing separated at the outboard attachment boltholes in a jagged pattern; the spar bent upward. The top wing remained attached to a 6-inch section of the carry through spar; this section of the carry through spar separated from the center fuselage section. It exhibited permanent upward deformation at the root; the spar webbing buckled with a diagonal crease pointing to the top wing root. The wing bowed down several degrees from outboard of the walkway area to the tip. The flap remained attached at the inboard and center hinge; the outboard hinge separated in a jagged pattern. The wing tip and its integral fuel tank separated at the outboard rib. The screws securing the tip to the rib remained in their nutplates; the skin on the tip sheared inboard at each screw hole. The vertical stabilizer separated. The aft spar separated near the midpoint, and the bottom half twisted 180 degrees forward on the left side. The skins tore apart from the rear to the back edge of the leading edge spar in an irregular pattern and angled up. The top section of the rudder remained attached to the upper hinge. Most of the rudder remained attached to the empennage at the lower hinge. The rudder surface bent to the right side with extensive wrinkling and buckling. The left horizontal stabilators separated outboard of the hinge fitting. The surface exhibited a permanent downward deformation with diagonal creases pointing towards the leading edge of the tip section. The trim tab remained attached. The right horizontal stabilator separated outboard of the hinge fitting. The surface exhibited a permanent downward deformation. The leading edge had a semicircular dent. The trim tab remained attached. The center section of the horizontal stabilators remained attached to the empennage. Both ends exhibited downward deformation and forward twist. The left aileron remained attached to the wing; however, the aileron bellcrank assembly was pulled outside of the wing. The aileron cables remained attached to the bellcrank assembly. The cables separated at the wing root in a broomstraw pattern. The right aileron cables remained attached to the bellcrank assembly. The cables separated at the wing root in a broomstraw pattern, and sawtoothed into the upper right wing skins. The rudder cables remained attached to the rudder horn. The lower cable remained attached to the horizontal bar; the upper attachment fitting, with the upper cable attached, separated from the bar assembly. The bar assembly went through the top of the empennage skin. The fuel selector valve separated from the floor, but remained attached to the fuel lines. It was in the left main fuel tank position. The stabilators' trim tab was at zero threads. Engine Investigators slung the engine from a hoist, and removed the spark plugs. The gaps for all plugs were similar. Top plugs for cylinders numbers one, four, and five sustained mechanical damage; none of the bottom spark plugs sustained damage. The top spark plug center electrodes for cylinders number two, three, and six and all electrodes for the bottom spark plugs were oval and gray, which corresponded to normal operation according to the Champion Aviation Check-A-Plug AV-27 Chart. A borescope inspection revealed no mechanical deformation on the valves, cylinder walls, or internal cylinder head. The crankshaft would not rotate with the propeller. After debris was removed, the crankshaft rotated with the propeller about 20 degrees. Both magnetos separated from their respective mounting pads. They sustained mechanical damage, and could not be tested. The carburetor sustained mechanical damage, and was breached. The floats fractured and separated. The finger screen was clean. The wet vacuum pump sustained mechanical damage, and the vanes fractured into multiple pieces. The oil sump sustained mechanical damage, and was breached. The oil sump screen was clean. The oil filter was crushed.
The pilot exceeded the design stress limits of the airplane, which resulted in the in-flight separation of the wings and horizontal stabilizers. Contributing to the accident were the night lighting conditions, clouds, turbulence and icing conditions.
Source: NTSB Aviation Accident Database
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