NTSB Factual Report

HISTORY OF FLIGHT:

On November 8, 1993, at 2025 central standard time, a Cessna 182P, N182JS, was destroyed during an uncontrolled descent near Marlow, Oklahoma. The commercial pilot and the two passengers sustained fatal injuries. Instrument meteorological dark night conditions existed for the business cross country flight to Oklahoma City, Oklahoma.

The flight departed Expressway Airpark, Oklahoma City, Oklahoma, earlier that day and arrived at Duncan, Oklahoma, for a business meeting at approximately 1730. After the meeting, on a car phone en route to the airport, the pilot telephoned for an abbreviated weather briefing. He then told the occupants of the car that there was fog 40 miles west of Oklahoma City and that they needed to go directly to the airport for departure, vice stopping for dinner.

Witnesses reported overcast conditions and drizzle in the Marlow area at 2000 central standard time. One witness reported hearing an airplane circle her home about 2025. The witness was unable to see the airplane due to clouds. She further stated that it circled several times in a counter clockwise direction and then departed to the northwest. She said the engine "sounded fine." About 20 seconds later she observed a "white flash of light close to the horizon" and then she did not hear the airplane. Impact occurred about 1/2 mile from her house.

During that weather briefing the pilot was asked if he could go IFR. He responded "I don't want to but I guess I can if I have to." The briefer informed the pilot that Dallas was IFR and that Ardmore was "very marginal."

PERSONNEL INFORMATION:

Records indicated that from September, 1973, through August, 1986, the pilot flew numerous cross country flights throughout Oklahoma. Pilot flight logbooks after 1986 were not available to the Board. Oklahoma Air National Guard records indicated flight time of 3 hours in rotorcraft in the previous 90 days, including an instrument check in a Bell UH-1 on September 29, 1993.

AIRCRAFT INFORMATION:

The airplane was owned and operated by the pilot. His registration certificate was issued on November 9, 1988. A damage and vacuum leak inspection of the pitot static system was done on July 3, 1992. The airplane was inspected in accordance with an annual inspection and a list of discrepancies and unairworthy items dated April 25, 1993, was provided for the airplane owner. According to the manufacturer, the 1956 model airplane was originally plumbed for two vacuum instruments with no vacuum instruments installed. At an unknown date plumbing to support a third vacuum instrument was installed. No logbook entries were found to document the original installation of any gyroscopic instruments or any modifications of the vacuum system to support three vacuum instruments.

METEOROLOGICAL INFORMATION:

Surface weather observations and area forecasts throughout Oklahoma indicated ceilings from 1,500 feet to 4,800 feet overcast with visibility lowering due to fog. No observation was available for Marlow; however, residents reported instrument meteorological conditions.

COMMUNICATIONS:

Fort Sill (FSI) Army Radar Approach Control (ARAC) transcripts revealed the following information. At 2017:58 the pilot radioed that he departed Duncan, Oklahoma, was trying to remain in visual conditions, and was requesting the current weather for Oklahoma City, Oklahoma. The controller issued a transponder code and the pilot transmitted "I'm sorry I I'm low I'm trying to stay visual and uh I cannot receive that squawk say again." At 2019:37 the pilot reported being about 10 miles north of Duncan climbing in instrument meteorological conditions, and requested Oklahoma City weather. After receiving his destination weather, 1,500 overcast and visibility of 10 miles, he requested an instrument clearance.

Clearance was issued at 2020:42 with an assigned altitude of 7,000 feet, which was later changed to 5,000.

At 2024:05 the pilot transmitted "Two Juliet Sierra I have uh a vacuum problem and uh panel situation here so I I'm going to be a little limited on being able to talk to you." At 2024:27, in response to a flight plan change, the pilot transmitted "Roger Two Juliet Sierra I'm going to have to fly the airplane." That was the last recorded radio transmission.

WRECKAGE AND IMPACT INFORMATION:

The terrain was rolling grassland bordered by a treeline. A ground scar approximately the length and width of the left wing leading edge was found near the base of 20 foot tall trees. Numerous tree limbs were located in the vicinity of the ground scar. The airplane propeller hub disintegrated with one propeller blade, hub, and governor buried in the ground. The #6 cylinder separated from the engine which came to rest 300 feet beyond the cylinder. See the enclosed manufacturer report for a description of the impact damage to the engine. The second propeller blade was found 200 feet from the cylinder. Both propeller blades exhibited scratches, scoring, and gouges. One blade was bent and twisted.

Wings, elevator, and rudders were crushed along the leading edges. The airplane distribution pathway was on a measured magnetic heading of 350 degrees (see enclosed diagram). Part of the vacuum pump attachment plate remained attached at the engine accessory pad. Half of the vacuum pump data tag was located and the pump was identified as wet pump Type B-11. The vacuum pump was not located. The vacuum relief valve (Cessna P/N AN61194), attitude gyro rotor and housing, turn and bank gyro (rotor and portion of gimble), and directional gyro (rotor and gimble) were found approximately 200 feet from the initial impact ground scar.

MEDICAL AND PATHOLOGICAL INFORMATION:

The Office of the Chief Medical Examiner of Oklahoma City, Oklahoma, performed an autopsy on the pilot. Autopsy findings were insignificant and toxicological results were negative.

TEST AND RESEARCH:

The vacuum relief valve was bench tested on January 14, 1994. The valve functioned per design and a report is enclosed.

The gyro instrument components were examined (report enclosed) utilizing microscopic and energy dispersive analysis of x-ray (EDAX). Localized rub marks were identified by metallurgists as rotation marks on the attitude indicator rotor, case, and casing top. The rotor was identified as brass and the case as aluminum alloys. Traces of aluminum alloy were identified in the rub marks. Two cracks were observed in the bearing race of the attitude indicator shaft. Fracture face morphology of the contact surfaces indicated overload as the mode of cracking.

The vacuum instrument components were further examined by metallurgists at a later date (enclosed report). The attitude gyro exhibited rotational impact signatures. Rotational impact signatures were not found on the turn and bank gyro rotor. Gyro bearings for the turn and bank gyro were "heavily corroded and bore no evidence of recent rotation." There was no wear path on the outer bearing race or bearing balls for the turn and bank indicator. The directional gyro rotor was capable of "unconstrained rotation about the central shaft." There was no evidence of rotational damage on the directional gyro rotor.

The directional gyro filter contained debris. On May 24, 1994, a functional flow test (enclosed report) for the directional gyro filter was conducted at Material Analysis, Inc. of Dallas, Texas.

The directional gyro test instrument functioned during turns to the left and right.

Examination (enclosed report) of the turn and bank inner bearings was conducted at Materials Analysis, Inc. These bearings were found to be within the design tolerances.

ADDITIONAL INFORMATION:

The airplane was released to the owner's representative.

NTSB Probable Cause

AN INOPERATIVE VACUUM SYSTEM, AN INOPERATIVE TURN & BANK INDICATOR, AND AN INOPERATIVE DIRECTIONAL GYRO, WHICH RESULTED IN AN INABILITY OF THE PILOT TO CONTROL THE AIRPLANE AFTER IT ENCOUNTERED INSTRUMENT METEOROLOGICAL CONDITIONS (IMC). FACTORS RELATED TO THE ACCIDENT WERE: DARKNESS, FOG, AND DRIZZLE.