NTSB Factual Report

HISTORY OF FLIGHT

On September 22, 2006, at 0958 central daylight time, a Beech 95-B55, N4JV, collided with the terrain in North Sioux City, South Dakota. The airplane was in cruise flight at 9,000 feet above mean sea level (msl) prior to radar and radio contact being lost. The pilot was fatally injured. The airplane was substantially damaged. The 14 Code of Federal Regulation Part 91 business flight was operating in instrument meteorological conditions. The pilot had filed and activated an instrument flight rules (IFR) flight plan. The flight originated from the North Platte Regional Airport (LBF) North Platte, Nebraska, at 0853 with an intended destination of La Crosse, Wisconsin.

Personnel at the fixed base operator (FBO) at LBF stated the airplane arrived at their airport on September 19, 2006. The pilot instructed line personnel to fill up the main fuel tanks. The FBO reported they filled the main fuel tanks with 74.7 gallons of fuel. The airplane was then tied down until it departed on the accident flight.

At 0944, the pilot of N4JV contacted Sioux City approach control stating that he was at 9,000 feet. At 0954, the approach controller informed N4JV that the Crypt military operations area (MOA) to his east was active. The controller stated that he could either go 5 miles to the north or he could descend to 7,000 feet to avoid the MOA. The pilot did not respond to this radio call. At 0955, the controller again called N4JV at which time the pilot responded with his call sign. The controller repeated his earlier call about the MOA. The pilot did not respond to numerous attempts by the controller to contact him.

According to the Sioux City Approach Radar the first radar contact they had with the airplane was at 0940:38 when it was at a reported altitude of 8,800 feet. The airplane then climbed to an altitude of 9,000 feet where it remained until 0955:56 when it began a descending left turn. At 0956:26, the altitude data went into coast mode and the ground speed was reported as being 204 knots. Four seconds later, radar data shows the airplane turning to the right with a ground speed of 50 knots at an altitude of 7,400 feet. At 0956:34, the airplane enters another left turn and is still descending. At 0956:48, the altitude was recorded as being 5,200 feet with a ground speed of 29 knots. The altitude data then once again entered the coast mode.

A witness reported seeing the airplane spinning slowly as it descended in a nose down attitude. Other witnesses reported seeing the airplane spinning as it descended out of the clouds with variations in the engine sounds.

PERSONNEL INFORMATION

The pilot, age 55, held an airline transport pilot certificate with a multi-engine rating and commercial pilot privileges for single-engine land airplanes. This certificate was issued on November 30, 1979. The pilot also held a flight instructor certificate with multi-engine, single-engine, and instrument ratings, which was renewed on July 29, 2006. The pilot was issued a second-class medical certificate on June 5, 2006. This certificate contained the limitation that the pilot must have glasses available for near vision.

The pilot's family provided a computerized printout of flight time records that the pilot maintained. The printout began on March 16, 1999, with flight times carried over from prior logbooks. According to these records the pilot had a total of 6,698.6 hours of flight time of which 4,115.7 hours were in multi-engine airplanes. The printout showed the pilot had flown a total of 107.5 hours in the accident airplane. It is unknown if he had additional flight time in the same make and model airplane prior to what was logged on the printout. The most recent record of the pilot's instrument flight time was his application for renewal of his flight instructor certificate, which was dated August 2004. This application showed the pilot had in excess of 560 hours of instrument flight time.

AIRCRAFT INFORMATION

The accident airplane was a 1973 Beech 95-B55, serial number TC-1583. It was a multi-engine, low wing, six-place airplane with retractable landing gear. A review of the maintenance logbooks indicated the most recent annual inspection was completed on September 11, 2006, at a total airframe time of 3,292.1 hours.

The airplane was equipped with two 260-horsepower, fuel injected, Continental IO-470-L (21) engines. The left engine, serial number 454091CS, was overhauled and installed on the airplane on November 24, 1993. The right engine, serial number 454092 CS, was overhauled and installed on the airplane on November 4, 1999. Both engines received an annual inspection on September 11, 2006. Total time since overhaul on the left and right engines at the annual inspection was 1,623.5 hours and 582.1 hours respectively.

METEOROLOGICAL CONDITIONS

The pilot received a Direct User Access Terminal System (DUATS) weather briefing for the flight on September 21, 2006, at 2225. He then received a Flight Service Station weather briefing at 0802 on the morning of the accident. The pilot was provided with the current and forecast weather conditions, freezing levels, and Airman's Meteorological Information (AIRMETs) along the route of flight.

Weather conditions recorded at the Sioux City Gateway Airport (SUX), Sioux City, Iowa, located about 9 miles southeast of the accident site, at 0952, were: Wind from 220 degrees at 7 knots; visibility 10 statute miles; ceiling 1,300 broken, 3,800 overcast; temperature 14 degrees Celsius; dew point 12 degrees Celsius; altimeter 29.30 inches of mercury.

The Safety Board prepared a Meteorology Factual Report for this accident. The report stated the accident site was located south-southwest of a low-pressure system and a trough of low pressure, and between an occluded and secondary cold front. The surface analysis chart depicted a cyclonic wind circulation pattern into the low-pressure system. Winds reported just south of the accident site were from the southwest and the winds reported just north of the accident site were from the north.

The Meteorology Factual Report continued to state, "Station models immediately north and east of the accident site indicated IFR conditions with visibility 4 to 5 miles in rain with ceilings overcast at 500 feet agl [above ground level], with MVFR [marginal visual flight rules] conditions immediate south and west over northeastern Nebraska and central Iowa." The report also states that light to moderate rain showers were depicted in the vicinity of the accident site and the Freezing Level Chart implied a freezing level below 9,400 feet near the accident site. The radiative cloud top temperature near the accident site indicated the tops of the clouds were near 17,000 feet.

The airplane was operating within an area that was covered by AIRMET Tango update 2 which called for occasional moderate turbulence below 10,000 feet and AIRMET Zulu update 2 which advised of occasional moderate rime to mixed icing in clouds and in precipitation between the freezing level and 24,000 feet.

Witnesses reported rain in the area at the time of the accident. Witnesses also reported they did not see any visible ice on the airframe after the accident.

WRECKAGE AND IMPACT INFORMATION

The accident site was located in a field between Interstate 29 and South Derby Lane. The wreckage came to rest 20 feet west of the Gunderson Fireworks building and 5 feet north of a storage trailer. There was no evidence that the airplane had contacted either of the structures. The airplane came to rest on a magnetic heading of 002 degrees on top of a pile of discarded wood and aluminum. A Sheriff's Deputy reported there was a strong odor of fuel in the area when he arrived just after the accident.

The entire airplane was present in one location. Ground scars indicated very little movement of the airplane once it contacted the terrain. The bottom of the engine nacelles and wings, and the fuselage were compressed evenly. All of the flight control surfaces remained attached to the fuselage. Although not continuous due to impact damage, flight control continuity was established to all of the flight control surfaces. Both the flaps and landing gear were in the retracted position. Examination of the airframe and flight control system revealed no evidence of a preimpact mechanical failure/malfunction.

Both engines remained attached to the airframe although the engine mounts sustained impact damage. One propeller blade on the right engine was slightly bent aft at mid-span on the blade. The other blade had a slight rearward bend. Both blades were covered with mud/dirt. The right engine had one propeller blade that was undamaged and relatively free of dirt. The other blade was bent aft about 90 degrees at the mid-span of the blade and covered with dirt. None of the blades exhibited chordwise scratches or gouges. Thumb compression and suction were achieved on all cylinders on both engines when the crankshafts were rotated by hand. Spark was achieved on all spark plug leads or magneto terminals. No contamination was noted within the fuel system. Both vacuum pumps were intact and rotated freely. Examination of the engines and related system components revealed no evidence of a preimpact failure/malfunction.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy of the pilot was performed on September 23, 2006, at the St. Luke's Regional Medical Center, Sioux City, Iowa. The final autopsy report listed the probable cause of death as "Multiple acute blunt force traumatic injuries."

The FAA's Civil Aerospace Medical Institute performed forensic toxicology on specimens from the pilot. The report stated Metoprolol was detected in the blood and urine, and Naproxen was detected in the urine.

The pilot reported the use of Metoprolol during his last two FAA medical certificate examinations.

TESTS AND RESEARCH

Autopilot Servos

The aircraft owner stated that he and the accident pilot normally flew the airplane with the autopilot engaged. The autopilot servos were tested at Century Flight Systems under the supervision of the FAA. The servos tested to be functional and they operated normally.

Fuel System Components

There was a lack of residual fuel in the left engine fuel manifold and in the fuel lines from the manifold to the engine. The fuel pump, throttle and control assembly, fuel manifold valve, fuel nozzles from the left engine were bench tested at Teledyne Continental Motors under the supervision of the Safety Board. All of the components functioned normally.

Aileron Control Chain

The aileron control chain was sent to the Safety Board's metallurgical laboratory in Washington, D.C., for examination. The report prepared by the laboratory stated the inner and outer edges of the links adjacent to the fractured area were covered with corrosion pits. Examination of the fracture faces on each link revealed they were clean with no discoloration to indicate a pre-existing condition. The report continued to stated, "The outer edge of each link contained rounded depressions consistent with the corrosion pitting… . The fracture surface adjacent to the outer edge of the link displayed a shiny facetted surface that changed to a duller surface, inclined at approximately 45-degrees to the facetted surface, that grew wider as it approached the rivet hole."

Aileron Push-Pull Tube

The aileron push-pull tube was examined under a microscope and it exhibited features consistent with an overload failure.

ADDITIONAL INFORMATION

On September 2004, Raytheon Aircraft issued a Safety Communique regarding Spin Avoidance and Spin recovery Characteristics for all Beech Baron airplanes. This communique states:

"Failure to lower the nose and retard power immediately when a stall is encountered - and especially allowing power to remain on during spin entry or in a developed spin - tends to raise the nose (increase the angle of attack) and result in a spin from which recovery is far more difficult and sometimes impossible."

"All Baron Models tested have good spin avoidance characteristics. At the point of stall - even with asymmetric power - if the control column is immediately and briskly moved forward, lowering the nose to regain flying speed, and the power is simultaneously retarded, the airplane will recover immediately, reliably and smoothly. There is sufficient time to execute this control input even at the point of stall. A multi-engine pilot of ordinary skill can easily avoid an unintended spin."

NTSB Probable Cause

The pilot's failure to maintain control of the airplane during cruise flight, and subsequent inadvertent flat spin from which he could not recover. Contributing to the accident were clouds, turbulence, and rain showers.