Aviation Accident Summaries

Aviation Accident Summary LAX94FA006

SELIGMAN, AZ, USA

Aircraft #1

N91849

CESSNA 182M

Analysis

The pilot and his wife had traveled in their Cessna 182 from the east coast to the west coast on a vacation. About an hour into a return flight leg, the pilot experienced a total loss of engine power over a remote area of northern Arizona. The pilot attempted an emergency landing on a cattle ranch. Ranch personnel stated that the engine was running erratically. The airplane collided with a telephone wire and a berm, which obscured a natural wash. The nose gear was sheared off, the airplane went inverted, and impacted the far side of the wash. The engine was shipped to the manufacturer. After minor repairs, the engine was started and shut down after fuel was observed running out of the carburetor throat. Internal examination of the carburetor revealed that the two screws that hold the float and needle valve in position had backed out. The carburetor was disassembled and the float replaced in compliance with a service bulletin 250 hours prior to the accident.

Factual Information

On October 8, 1993, at 1021 hours mountain standard time, a Cessna 182, N91849, was destroyed in multiple obstacle collisions during an emergency landing attempt near Seligman, Arizona. The airplane was owned and operated by the pilot, and was on a personal cross country flight at the time. Both the commercial pilot and his passenger received fatal injuries. Visual meteorological conditions prevailed for the flight and no flight plan was filed. The flight had originated at Las Vegas International Airport, Nevada, on the morning of accident with an unknown destination. Prior to departure at 0837 hours PST, the airplane had been fueled with 30.7 gallons of 100LL aviation fuel. Records recovered at the accident site document an extended cross country flight originating at Fall River, Maine, on or about September 24, 1993. The pilot and passenger flew west to Carlsbad, California, where they arrived on October 1, 1993. The flight then departed east bound on October 5, 1993, to Las Vegas, Nevada. The accident site was located about 13.5 miles south of Seligman on Williams Valley Road at the Yavapai Ranch. Ranch employees witnessed the pilot's attempt to land on the road. They stated that the airplane was very low southbound over the ranch corrals attempting to land, when it collided with some telephone lines. They stated that the engine sounded erratic with little or no power. Wheel tracks located in the soft ground revealed that the airplane collided with a berm and large boulder. The berm was located on the north side of a natural wash. The airplane was observed nose down near inverted on the south side of the wash. PERSONNEL INFORMATION According to the pilot's log book, he had accumulated about 1,265 hours of flight time. The pilot was rated for single and multi- engine land airplanes and single engine sea airplanes. The pilot was a certificated aircraft engine ground instructor and held both airframe and powerplant certificates. METEOROLOGICAL INFORMATION At 0950 hours MST, the Prescott FAA flight service station was reporting: 3,500 feet scattered, 9,000 feet scattered, 60 miles visibility, temperature 61 degrees fahrenheit, dew point 43 degrees fahrenheit, wind 180 degrees at eight miles per hour, and the altimeter setting was 30.04 inches of mercury. WRECKAGE AND IMPACT INFORMATION The wreckage was viewed laying near inverted against the embankment of a wash/ravine on the Yavapai ranch property. The wheel tracks approaching the wash were measured on a magnetic heading of about 110 degrees. Both wings exhibited major damage with the left wing severed from the fuselage structure. Fuel was noted to be leaking from both fuel tanks. The right wing strut was severed from the lower attach point. Heavy accordioning of the forward cabin structure and firewall area was noted into the cabin's occupiable space. According to measurements taken of the flap jack screw, the wing flaps were in the up position. MEDICAL AND PATHOLOGICAL INFORMATION On October 9, 1993, the Yavapai County Medical Examiner at Prescott, Arizona, examined the pilot's body. According to the medical examiner's report, the cause of the pilot's death was skull fractures as a result of the airplane accident. The toxicological examination was performed by the Maricopa County Office of the Medical Examiner in Phoenix, Arizona. The results were negative for alcohol and drugs. TESTS AND RESEARCH After the wreckage was recovered, a cursory examination of the engine was performed. The engine was then shipped to Continental Motors for an examination and a test run. Assessment of the engine damage revealed that, with the replacement of various induction, exhaust, and oil system components which sustained impact damage, the engine could be test run. The engine was installed in a test cell and started, however, fuel was observed leaking from the throat of the carburetor. The engine was shut down and the carburetor was removed. When the carburetor was opened for inspection, it was noted that the tab locks which secure the screws that hold the two carburetor bowl halves together, were not bent up to lock the screws in their torqued position. The screws were found loose. The floats and the needle valve were laying loose in the carburetor bowl. The two self-locking screws that hold the float/needle valve hinge bracket to the carburetor upper half were still in the hinge bracket and undamaged. The float hinge pin was in position and secured by a properly bent safety pin which had to be removed to reinstall the float and needle valve for the engine run. After the carburetor was properly reassembled and installed on the engine, it was restarted. The engine started and idled smoothly, and after warmup it was operated at full throttle for twenty minutes with no problems. The maximum rated rpm for this engine is 2,600 rpm, and the maximum obtainable rpm during the test run was 2,550 rpm. It was noted that the numbers one and three ignition leads were arcing to ground due to impact damage, causing an excessive rpm drop on the left magneto. The engine was subjected to several throttle bursts from idle to maximum rpm. Acceleration was smooth and without hesitation. A review of the maintenance records revealed that the last documented carburetor maintenance was performed on May 14, 1992, at a recording tachometer time of 1,763.76 hours. At that time, the log entry documented the replacement of the float assembly in compliance with service bulletin MSA-1, which concerns the replacement of composite floats with metal floats. The recording tachometer at the accident site indicated 2,013.97 hours. According to the carburetor manufacturer, the self-locking screws are installed and torqued in place to eight to eleven-inch pounds. The screws, once in place, are not normally removed, even at overhaul. If the screws are removed for any reason, they are to be replaced, as they have a nylon insert in the threads. ADDITIONAL INFORMATION The wreckage was released to Loss Management Services, Inc., and a copy of the release was received back on June 9, 1994.

Probable Cause and Findings

the separation of the carburetor float and needle valve from the upper half of the carburetor bowl, due to improper installation of the float kit.

 

Source: NTSB Aviation Accident Database

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