NTSB Factual Report

HISTORY OF FLIGHT

On September 30, 2004, about 1630 central daylight time, a Beech B95A, N1703Y, piloted by a commercial pilot, was destroyed when it impacted trees and terrain after takeoff from runway 11 (4,300 feet by 75 feet, asphalt), at the Burlington Municipal Airport (BUU), Burlington, Wisconsin. The 14 CFR Part 91 flight was operating in visual meteorological conditions without a flight plan. All three occupants of the airplane were fatally injured. The flight was originating at the time of the accident and was en route to the Westosha Airport, Wilmont, Wisconsin.

According to a witness, the airplane departed using runway 11 and was observed to make a right turn that increased in bank angle until the airplane impacted the ground. The airplane came to rest at the rear edge of a residential property near the airport. On October 1, 2004, the airplane was recovered from the accident site to a hangar at BUU where further examination was conducted.

PERSONNEL INFORMATION

The pilot seated in the left pilot station held a commercial pilot certificate issued by the Federal Aviation Administration (FAA). The certificate included single engine land, multi-engine land, and instrument airplane ratings. The pilot had received his commercial multi-engine land rating on March 9, 2003. He also held a flight instructor certificate with single engine and instrument airplane ratings. The pilot held a FAA first class medical certificate issued on April 15, 2004. The medical certificate listed the limitation, "must wear corrective lenses". A review of pilot logbooks bearing the name of this pilot indicated that he had accumulated 1,508.2 hours total flight experience and 146.3 hours of multi-engine experience as of the last entry dated September 28, 2004. The logbook listed 243.3 hours accumulated in the last 90 days, of which, 50.4 hours were in multi-engine airplanes. Of those 50.4 hours, 48.4 hours were in the accident airplane.

The pilot rated occupant seated in the right pilot station held a FAA commercial pilot certificate. The certificate included single engine land, multi-engine land, and instrument airplane ratings. He also held a flight instructor certificate with single engine, multi-engine and instrument airplane ratings. He held a FAA first class medical certificate issued on November 18, 2002. The medical certificate listed the limitation, "must wear corrective lenses".

AIRCRAFT INFORMATION

The airplane was a twin-engine Beech model B95A, serial number TD-498. This model, also known as the Travel Air, is a low-wing monoplane with an aluminum primary structure and retractable landing gear. Two wing-mounted Lycoming model IO-360-B1A engines powered the airplane. Each fuel-injected engine was rated for 180 horsepower. The accident airplane was manufactured in 1962 and was configured to seat 4 occupants.

A review of the maintenance records showed that the airplane had undergone an annual inspection on November 1, 2003. The airplane had accumulated 7,934.7 hours total time in service at the time of the annual inspection. According to the recording hour meter readings from the accident site and the annual inspection entry, the airplane had accumulated an additional 202.3 hours since the annual inspection.

According to maintenance records, the left engine, serial number L1526-51, had accumulated 1,941.4 hours since overhaul as of the annual inspection on November 1, 2003. The last recorded overhaul was performed on October 1, 1977.

According to maintenance records, the right engine, serial number L1525-51, had accumulated 1,262.3 hours since overhaul as of the annual inspection on November 1, 2003. The last recorded overhaul was performed on May 26, 1990.

METEOROLOGICAL INFORMATION

The BUU weather at 1636 was recorded as: Winds 170 degrees at 6 knots; Visibility 10 statute miles; Sky condition clear; Temperature 23 degrees Celsius; Dew point 2 degrees Celsius; Altimeter setting 29.98 inches of mercury.

WRECKAGE AND IMPACT INFORMATION

The airplane impacted the ground at the rear of a residential property adjacent to a marsh area. Using a global positioning system receiver, the wreckage location was determined to be at 42 degrees, 41.140 minutes north latitude, 88 degrees, 17.664 minutes west longitude. The airplane came to rest in a nose low attitude with the aft portion of the airplane resting on trees. The forward fuselage was crushed rearward to the leading edge of the wing root. The leading edges of the wings were crushed rearward. A linear impact scar was found adjacent to the wing leading edges. The right wing outboard of the engine nacelle was separated and impacted around a tree. All of the tail surfaces remained attached to the aircraft. The left engine, propeller, cowl and firewall were partially separated from the nacelle just aft of the firewall. The right engine, propeller and cowl remained attached to the nacelle. Subsequent to these observations, the airplane was removed from the accident site and placed in a hangar for further examination.

The aircraft control system was examined. Continuity of the rudder, aileron, and elevator control cabling was confirmed from the cockpit to the respective control surfaces. All of the flight control surfaces remained attached to the mating portions of the airframe. The flaps and landing gear were found in the retracted position.

The left engine was inspected in a hangar after removal from the accident site. The engine remained attached to the firewall. The propeller and spinner remained attached to the engine. The spinner was crushed in a spiral shape. Both propeller blades were bent aft. The fuel servo was separated from the mounting flange. Both magnetos remained attached to the accessory section of the engine. The crankshaft was rotated by hand and continuity of the crankshaft, camshaft, and accessory gears was confirmed. Compression and suction was confirmed on all cylinders during crankshaft rotation. Spark was confirmed from each magneto lead while the engine crankshaft was rotated. During rotation of the crankshaft, oil was noted being pumped out of the hose fitting that had been disconnected from the oil cooler. Fuel was found in the fuel lines from the fuel pump to the fuel servo and from the fuel servo to the flow divider. The flow divider diaphragm was found intact.

The right engine was inspected in a hangar after removal from the accident site. The engine remained partially attached to the firewall. The propeller and spinner remained attached to the engine. The spinner was crushed on one side. One of the propeller blades was bent slightly forward and the other blade was bent slightly aft. The fuel servo remained attached to the engine. Both magnetos remained attached to the accessory section of the engine. The crankshaft was rotated by hand and continuity of the crankshaft, camshaft, and accessory gears was confirmed. Compression and suction was confirmed on all cylinders during crankshaft rotation. Spark was confirmed from each magneto lead while the engine crankshaft was rotated. During rotation of the crankshaft, oil was noted being pumped out of the hose fitting that had been disconnected from the oil cooler. Fuel was found in the fuel lines from the fuel pump to the fuel servo and from the fuel servo to the flow divider. The flow divider diaphragm was found intact.

The right engine was retained in order to attempt an engine run in a test facility. Details of the engine test run are in the "Tests and Research" section of this report.

The propeller manufacturer under the direct supervision of a Federal Aviation Administration inspector conducted examinations of the propellers from both engines. The installed propellers were hydraulically actuated with oil pressure from the propeller governor driving the propeller blades toward low pitch. The propeller incorporates a combination of counterweights and springs to drive the propeller toward the high pitch and feather positions. The examination revealed that both propellers were at a low pitch setting and that the start locks were engaged. Manual disengagement of the start locks resulted in the propellers moving to the feathered position.

MEDICAL AND PATHOLOGICAL INFORMATION

Autopsies were performed on the front seat occupants by the Waukesha County Medical Examiner, Waukesha, Wisconsin.

The Federal Aviation Administration prepared Final Forensic Toxicology Fatal Accident Reports for both front seat occupants. The results were negative for all tests performed.

TESTS AND RESEARCH

The right engine was transported to the manufacturer's facility to perform a test run in an engine test cell under the direct supervision of the National Transportation Safety Board's (NTSB) Investigator-In-Charge. The engine was installed in the engine test cell and operation of the engine was attempted using engine components from the accident aircraft. During these attempts, continuous operation was not achieved. The maximum engine speed attained during these attempts was approximately 1,000 revolutions per minute (rpm). Subsequent to the initial attempts, a representative fuel servo was installed on the engine. After installation of the representative fuel servo, the engine was again started and continuous operation was obtained. The engine was operated from idle through approximately 2,650 rpm. Engine acceleration was smooth and no hesitation was noted. Subsequent to the engine test runs, the fuel servo from the accident aircraft was sent for further examination. The engine manufacturer's report is included in the docket material associated with this report.

The aircraft's fuel servo was a Precision Airmotive Corporation model RSA-5AD1. The serial number of the unit was 43620. The servo was examined at the manufacturers facility under the direct supervision of a NTSB investigator. The fuel servo had a field overhaul tag affixed to it. The fuel servo was installed on a test fixture and a "flow" test performed. The flow test revealed that the fuel delivery of the accident aircraft fuel servo was not within the manufacturers specifications. The recorded fuel flows for each test point were below the minimum specifications. At test point number 8, the specifications indicate a fuel flow range between 120.0 and 125.2 pounds of fuel per hour (pph). The measured output of the accident aircraft's fuel servo at this test point was 14.5 pph. Disassembly of the fuel servo revealed that the outer regulator nut was loose from the stem. The nut was installed on the stem in order to measure the drag torque of the locking ring. No measurable drag torque was detected. The manufacturers specifications required a minimum of 3 ounce-inches of drag torque. The outer and inner nuts were found to have a silver coloration. According to the manufacturers report, the factory-supplied nuts are gold in color. The manufacturers test report is included in the docket material associated with this report.

Review of the maintenance records for the 5 years prior to the accident revealed no record of maintenance performed on the fuel servo.

ADDITIONAL INFORMATION

The Federal Aviation Administration, Textron Lycoming, Raytheon Aircraft, Precision Airmotive and Hartzell Propellers were parties to the investigation.

The wreckage was released to a representative of the insurance company.

NTSB Probable Cause

The improper maintenance of the fuel servo resulting in a loose adjustment nut and subsequent failure of the fuel injection servo which led to a complete loss of power on the right engine. Other causes were the pilot's failure to obtain or maintain minimum controllable airspeed which resulted in an uncommanded roll and subsequent impact with the ground.