NTSB Factual Report

On August 6, 1994, at 1545 hours mountain standard time, an Aero Commander 112, N1018J, lost power and collided with level desert terrain in Mohave Valley, Arizona. The airplane was being operated as an instructional flight by Copper State Flying Service, Inc. The airplane was destroyed. The certified flight instructor, a certificated private pilot, and a passenger received fatal injuries. The flight originated in Bullhead City, Arizona, about 1535 hours. Visual meteorological conditions prevailed at the time.

One of the pilots transmitted a distress call to the Bullhead City Airport air traffic control tower about 6 minutes after departure. The pilot indicated the engine had failed. There were no further communications from the accident airplane.

The airplane was found on August 8, 1994, about 7 nautical miles south of the airport. A hole was found in the engine case adjacent to a damaged piston rod.

Crew Information

First Pilot

The first pilot held an airline transport pilot certificate and a flight instructor certificate with ratings for single and multiengine airplanes. The most recent first class medical certificate was issued to the pilot on March 24, 1994, and contained no limitations.

No personal flight records were located for the first pilot, and the aeronautical experience listed in this report was obtained from a review of the airmen FAA records on file in the Airman and Medical Records Center located in Oklahoma City. In addition, information was obtained from a review of personnel records maintained by his previous employer.

According to the records, the pilot's total aeronautical experience consists of about 12,100 hours, of which about 8,000 hours were accrued in single engine airplanes. The first pilot's last biennial flight review was accomplished by completing an equivalent 14 CFR Part 135 flight check in a Cessna 421 on January 5, 1994.

Second Pilot

The second pilot held a private pilot certificate with a single engine airplane rating. The most recent third class medical certificate was issued to the pilot on November 10, 1992, and contained the limitation that correcting lenses be worn while exercising the privileges of his airman certificate.

Only one of the second pilot's logbooks was located. The logbook indicated it was the pilot's third logbook and covered the period from November, 1992, to present. The aeronautical experience listed in this report was obtained from the logbook and investigator estimates. It could not be determined if the second pilot had a current biennial flight review.

The second pilot's total aeronautical experience consists of about 317 hours, of which at least 19 hours were accrued in the Aero Commander 112. In the preceding 90 and 30 days prior to the accident, a total of 15 and 2 hours, respectively, were flown.

Aircraft Information

The airplane had accumulated a total time in service of 2,626 hours. Examination of the maintenance records revealed that the most recent annual inspection was accomplished on January 6, 1994, about 160 flight hours before the accident.

A Lycoming IO-360-C1D6 engine, serial number L-9013-51A was installed in the airframe on September 22, 1972, and also had accrued a total time in service of about 2,626 hours. The maintenance records noted that a major overhaul was accomplished on June 1, 1979, about 1,420 flight hours before the accident, by Central Texas Engines, Repair Station Number 210-50.

According to the Federal Aviation Administration, the company that overhauled the engine is no longer in business and a copy of the overhaul work order was not obtained during the investigation. There was no evidence of the engine being removed from the airframe since the engine overhaul after a review of the available maintenance records.

Fueling records at Bullhead Airport, Inc., Bullhead City, Arizona, established that the airplane was last fueled on August 6, 1994, with the addition of 5 gallons of 100LL octane aviation fuel in each wing tank.

Wreckage and Impact Information

The airplane came to rest in a desert wash about 7 nautical miles south of the Laughlin-Bullhead City Airport at latitude 35-02.9 degrees north, and longitude 114-31.47 degrees west. The initial impact point was marked with a gouge in the soil followed by a 40-foot long wreckage path oriented on an 350 degree magnetic azimuth.

There was undisturbed desert shrubbery between the airplane's initial impact point and the wreckage point of rest. The airplane was found inverted. The longitudinal axis of the airplane was about 45 degrees right of the wreckage path.

The fiberglass engine cowling separated and was found about 20 feet behind the airplane on the right side of the wreckage path. There was no evidence of oil on the outside of the cowling. There was damage to the right side of the cowling above the number 1 cylinder. There was corresponding impact damage also noted on the engine at the number 1 cylinder.

The engine had a hole in the left crankcase half. The number 4 piston connecting rod was detached from the crankshaft and was protruding through the case.

The right wing was mangled outboard of the flap panel. The right main landing gear wheel and tire were separated. The remnants of the gear strut were extended from the wheel well.

The left wing exhibited damage to the leading edge. The left fuel tank was punctured. Dirt was adhering to the sheet metal skin in a liquid spray pattern. A liquid run pattern was also noted in the dirt adhering to the left wing running down from the spray pattern. The left main landing gear was found in the wheel well.

The empennage was bent up about 90 degrees forward of the vertical stabilizer. The top of the vertical stabilizer and rudder were damaged from ground contact.

Tests and Research

Engine Examination

The engine was examined on August 18, 1994, at Air Transport, Phoenix, Arizona. After engine disassembly it was noted that the number 4 (rear) main bearings displayed distress, and the number 4 connecting rod bearings were completely extruded. Further examination revealed the number 3 main (center) and number 4 main (rear) bearing bosses had been repaired by welding. According to the engine manufacturer, the saddles displayed gas holes caused by impurities in the filler material. The oil supply hole that supplies lubrication to the previous mentioned number 4 connecting rod bearing was welded shut and had not been bored. A work order number, " AJAX 1032," was noted on both crankcase halves. Investigation revealed the crankcases were repaired at one time by Ajax Aviation, Inc., San Antonio, Texas.

The crankcases were submitted to a metallurgic and failure analysis laboratory for examination. The number 3 main (center) and number 4 main (rear) bearing bosses were lightly etched to reveal the underlying microstructure. According to the metallurgist, the microstructure was consistent with a welded structure. A demarcation line was visible distinguishing the weld area from the original casting.

The case half was also x-rayed in the area of the weld over the oil supply hole. The original oil passage hole was visible in the x-ray under the filler material of the weld. A copy of the metallurgist's report is attached as part of this factual report.

Additional Information

Wreckage Release

The wreckage was released to the owner on August 18, 1994. The engine case halves were released to the owner representative on October 28, 1994.

NTSB Probable Cause

Failure of the certified flight instructor to properly judge the flare to avert a hard landing, and the failure of other maintenance personnel to properly repair the engine case halves during engine overhaul. A factor in the accident was the uneven relief of the desert terrain.