MOBILE, AZ, USA
N3172P
Beech F-33A
The airplane collided with terrain while on a low level navigation exercise and was almost totally consumed in a postcrash fire. The pilots were members of the German Air Force (GAF) and the flight was a low level navigation mission as part of an initial air force pilot training course. The flight syllabus called for the flight to complete the route at 500 feet agl. Another airplane with two GAF instructors aboard departed immediately after the accident airplane. The two instructors in the second airplane initially flew north of the standard route and then turned south to intercept it. They were about 1,500 agl. As they turned south, they observed the accident airplane proceeding on a southeasterly course. Both instructors said that they were looking down at the other airplane, and both estimated its altitude was 500 to 700 agl. Both instructors said the accident airplane was in straight and level flight on a southeasterly heading. As the airplane crossed the ridge, the airplane went from straight and level to a 30- to 40-degree angle of bank. The bank angle seemed to increase to 60 degrees and continued to 135 degrees as the nose went down. It appeared to the pilot in the left seat that the maneuver was abrupt, but he saw nothing to account for it. He didn't observe any obstacles to avoid, any smoke or flames coming from the airplane prior to impact, and he did not see anything falling from the airplane. The weather was clear and there was no turbulence. The airplane came to rest in an upright position. Vegetation ranging between 3 and 20 feet in height, and within 5 to 30 feet both behind and in front of the wreckage, was scorched but undamaged. Examination of the wreckage and ground scars disclosed that the airplane impacted the hillside in an attitude level with the slope and with a large vertical energy vector. Pieces of airframe and debris that came to rest outside of the charred areas were not sooty or discolored. Control continuity existed from the control surfaces to the thermally destroyed cabin area. There was no evidence of a catastrophic engine malfunction.
HISTORY OF FLIGHT On August 15, 2001, about 0700 mountain standard time, a Beech F-33A, N3172P, collided with terrain near Mobile, Arizona. Airline Training Center Arizona, Inc., was operating the airplane as an instructional flight under the provisions of 14 CFR Part 91. The certified flight instructor (CFI) and a student pilot sustained fatal injuries; the collision sequence and a post crash fire destroyed the airplane. The cross-country flight departed Goodyear, Arizona, about 0645 on a round robin low level navigation training flight. Visual meteorological conditions prevailed and no flight plan had been filed. The primary wreckage was at coordinates 32 degrees 58.84 minutes north latitude and 112 degrees 14.39 minutes west longitude, at an estimated altitude of 1,635 feet. The operator reported that the pilots were members of the German Air Force and the flight was a low level navigation mission. The flight syllabus called for the flight to complete the route at 500 feet above ground level (agl). The flight plan called for a southwesterly departure, two segments in a southeasterly direction, three segments in an easterly direction, and four segments to a westerly direction as the airplane returned to Goodyear. Another airplane with two instructors aboard departed immediately after the accident airplane. This aircrew planned to complete the last southeasterly and first easterly segments of the same route as the accident airplane. They did not observe the accident airplane during preflight, but did observe that its takeoff and initial climb seemed normal. They lost sight of the airplane about 2 minutes after departure, when they altered their course. The two instructors in the second airplane initially flew north of the standard route and then turned south to intercept it. They were about 1,500 agl. As they turned south, they observed the accident airplane proceeding on a southeasterly course. Both instructors said that they were looking down at the other airplane, and both estimated its altitude was 500 to 700 agl. Both instructors said the accident airplane was in straight and level flight on a southeasterly heading. One instructor thought the airplane was slightly north of a ridgeline rather than slightly south of the ridgeline as he normally flew the route. The pilot in the left seat observed the accident airplane, which was about 20 degrees right of the nose of his airplane and 3 miles from him. As the airplane crossed the ridge, the airplane went from straight and level to a 30- to 40-degree angle of bank. The bank angle seemed to increase and the nose went down. The accident airplane was definitely nose-low, and he lost sight of it behind the mountain. It appeared to the pilot in the left seat that the maneuver was abrupt, but he saw nothing to account for it. He didn't observe any obstacles, any smoke or flames prior to impact, and did not see anything falling from the airplane. The weather was clear and there was no turbulence. He said the other airplane was heading east and the sun was low and that could have been a factor. The instructor in the left seat pointed out the accident airplane to the pilot in the right seat; it was low at the 1-o'clock position. The instructor in the right seat said it appeared to be flying straight and level. He watched it for a minute or two before he lost it below the nose of his airplane. The instructor in the right seat said they continued southwest, and then turned to the southeast to pickup the route past the Serene Airport. He saw the accident airplane at his 12- to 1-o'clock position. He saw the airplane for less than a minute. He thought the airplane entered a bank angle approaching 60 degrees and continued to 135 degrees. His pilot made a correction and he lost the accident airplane under the right wing. Two to 4 seconds later he saw a fireball and smoke. The instructor in the right seat said they monitor 122.75 while on the route and he did not hear any broadcasts from the other airplane. He thought visibility was good and not a factor. The winds were calm and they did not experience any turbulence. PERSONNEL INFORMATION The operator reported that the pilot held a commercial pilot certificate with ratings for airplane single engine land, as well as instrument airplane. He held a certified flight instructor certificate with ratings for airplane single engine land and instrument airplane. They reported the pilot had a total time of 2,382 hours. He had accumulated 130 hours in the last 90 days, and 31 hours in the last 30 days. The pilot held a second-class medical certificate dated November 2, 2000, with no limitations or waivers. The second pilot held a student pilot certificate. A review of his training records revealed he completed his first flight on July 10, 2001, and had accumulated about 32 hours total time. This flight was the last flight in this phase of his training. Upon its successful completion, he would have returned to Germany for advanced training. The instructor in the left seat of the second airplane said he had known the accident instructor for about 1 year. At the morning briefing, the instructor appeared normal. The instructor in the right seat of the second airplane said he had known the accident instructor for almost 2 years and knew him pretty well. He talked to the instructor that morning and said he sounded in good spirits. AIRCRAFT INFORMATION The airplane was a Raytheon Beech F-33A, serial number CE-1090. A review of the maintenance records revealed a total time of 14,912 hours as of the daily inspection on the morning of August 15. The operator maintained the airplane on an approved airworthiness inspection plan (AAIP). The last inspection had been a phase-4 inspection, which occurred on August 6, 2001, at a total time of 14,890 hours. The engine was a Teledyne Continental Motors (TCM) IO-520-BB, serial number 813841-R. The daily inspection on the morning of August 15 recorded the total engine time as 1,452 hours. The propeller was a Hartzell model PHC-C3YF-1RF, serial number EE2366A. METEOROLOGICAL INFORMATION The nearest reporting station was Casa Grande (CGZ), Arizona, at 25 miles on a magnetic bearing of 085 degrees from the accident site. A routine aviation weather report (METAR) issued for CGZ at 0655 was: skies clear; visibility 10 statute miles; wind calm; temperature 79 degrees Fahrenheit; dew point 64 degrees Fahrenheit, and altimeter 29.94 InHg. WRECKAGE AND IMPACT INFORMATION Investigators from the Safety Board, Beech, and TCM examined the wreckage on scene on August 15 and 16. An additional examination occurred at Air Transport, Phoenix, Arizona, on August 17. The accident occurred in desert terrain characteristic of southern Arizona that was scattered with rock outcroppings. Cactus up to 20 feet high, and bushes 3 to 10 feet high, sparsely populated the terrain. The planned flight path took the airplane across the accident site ridgeline along a magnetic course of 110 degrees. The planned route traversed the southern section of the ridgeline, but the accident airplane traversed the northern section of the ridge. The ridge, about 3 miles long and 2 miles wide, generally ran in a north-south direction. It rose to an approximate height of 2,100 feet msl, which was about 600 feet above the surrounding terrain. The airplane came to rest upright and halfway up the north face of an east-west finger. At this point the crest of the finger was about 200 feet above the desert floor, and investigators estimated the slope at 25 degrees. The fuselage and debris path were aligned on a magnetic bearing of 250 degrees. Vegetation ranging in height between 3 feet and 20 feet, and within 5 feet to 30 feet of the wreckage, was scorched but undamaged. A ground scar ran parallel to and 2 feet away from the leading edge of the wings. At the left edge of this ground scar investigators found red lens fragments. The portion of the left wing outboard of the flap separated (except for the aft spar), was inverted with respect to the rest of the wing, and rotated about 60 degrees counterclockwise. The leading edge of the left wing tip was crushed up about 40 degrees. The right wing rotated about 5 degrees counterclockwise. Both wings exhibited aft crush damage to the lower skins. A 3-foot-high bush was between the bent left wing tip and the left horizontal stabilizer; the bush was scorched but otherwise appeared undamaged. Investigators accounted for all major airframe components and control surfaces at the accident site. They established control continuity from the control surfaces to a molten area in the center of the cabin. Both control yokes separated from the control column and the fracture surfaces were irregularly shaped. One yoke rested against the chest of the left seated pilot, and the other yoke lay on top of the right side of the engine. The right-hand grip from both yokes fractured and separated, and the fracture surfaces were irregularly shaped. The engine was partially separated and rotated about 45 degrees clockwise. The crankshaft fractured circumferentially just aft of the propeller mounting flange; the fracture surface angled 45 degrees to the longitudinal axis of the crankshaft. The propeller separated; two blades and the hub were to the left of the engine, while the third blade was under the engine. All three of the propeller blades exhibited leading edge gouges and S-bends. The separated blade exhibited chordwise striations, polishing along its cambered side, and it was bent in the direction opposite of rotation. Fire consumed the cabin; fire scorched the wings, forward portions of the vertical stabilizer, and the right horizontal stabilizer. Pieces of airframe and debris, such as Plexiglass and insulation, that came to rest outside charred areas were not sooty or discolored. Local fire personnel sprayed the airplane and put the fire out. Investigators identified the pieces in the debris field. The most distant piece of wreckage found was a 3-foot square section of top wing skin with a refueling port in it, which was about 30 feet forward of the main wreckage. The cabin entry door was leaning against a scorched but otherwise undamaged small tree at the 2-o'clock position from the wreckage, and about 10 feet forward of the right wing tip. Three feet from the right wing tip, the battery and the right side engine cowling lay under a scorched but otherwise undamaged bush. One emergency window exit frame was about 5 feet left of the propeller. The left elevator counterweight separated and was 2 feet forward of the left elevator. The outboard 2-feet of the left horizontal stabilizer was crushed up and aft. The Beech representative measured the elevator trim at 3 degrees tab up deflection. He said this would be a normal cruise setting. MEDICAL AND PATHOLOGICAL INFORMATION The Maricopa County Coroner completed autopsies of the pilot and student pilot. The Federal Aviation Administration (FAA) Toxicology and Accident Research Laboratory, Oklahoma City, Oklahoma, performed toxicological testing of specimens of both pilots. The results of analysis of the specimens for the CFI were negative for tested drugs. The report contained the following positive results: 26 (mg/dL, mg/hg) ethanol detected in the heart, and 1 (mg/dL, mg/hg) acetaldehyde detected in the heart. The report indicated putrefaction and a note said the ethanol found in this case may potentially be from postmortem ethanol formation and not from ingestion of ethanol. The results of analysis of the specimens for the student pilot were negative for tested drugs. The report contained the following positive results: 13 (mg/dL, mg/hg) ethanol detected in muscle. The report noted that the ethanol found in this case was from postmortem ethanol production and not from the ingestion of ethanol. TESTS AND RESEARCH Investigators placed the engine on a bench. The engine exhibited extensive thermal damage; the fire consumed many aluminum parts. The engine could not be turned by hand. The exhaust system was bent, buckled, and flattened, but did not fracture. Investigators removed the top spark plugs. All of the plugs were fine wire plugs and exhibited similar wear and gaps. Only the casing of the plug for cylinder No. 1 remained. The plug for cylinder No. 2 was gray, and the rest were slightly sooty. The right magneto separated from the engine at the accident site and the left magneto separated during recovery. Investigators could not obtain spark by manually rotating the magnetos. Upon disassembly, the internal components were found melted and discolored. The fuel metering unit's screen was clean. The fuel manifold screen was clean and its diaphragm was unbroken. The engine driven fuel pump sustained thermal and mechanical damage. It partially separated from the engine. Post accident investigation revealed a fracture of the fuel pump's steel drive shaft. The piece of drive shaft that remained in the engine was bent, and had a gray fracture surface with a rough, matte appearance. The exposed piece of shaft that remained in the pump was covered with rust. The shaft underwent further examination. TCM in Mobile, Alabama, completed metallurgical inspection of the fracture under the supervision of the FAA and submitted a written report, which is attached. The fractography of the fracture surface between the corrosion pits indicated a dimpled rupture across the entire surface. The metallurgist concluded that this was representative of an overload fracture. The coupling exhibited satisfactory hardness. ADDITIONAL INFORMATION The Safety Board released the wreckage to the operator at the conclusion of all examinations.
The flying pilot's initiation of an intentional maneuver at an altitude inadequate to maintain terrain clearance. Low altitude flight was a contributing factor.
Source: NTSB Aviation Accident Database
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