EL MONTE, CA, USA
N2340F
Cessna 210D
The aircraft had reached its cruise altitude of 8,500 feet when the engine smoothly quit. The pilot contacted a nearby airport control tower, reported the power failure, and said he needed to land. The local controller cleared the flight to land on any runway. Shortly thereafter, the pilot radioed that he would not make the field and landed gear-up in a dry wash area. During the landing, the aircraft collided with trees and an embankment. Examination of the airplane disclosed that the mixture control cable was fractured and disconnected from the cable's rod-eye end, which was still attached to the mixture arm of the fuel metering unit. The break in the cable was at the engine rod-eye end of the flexible cable at the point where the cable is swaged onto the rod. A metal outer sheath slides over the rod and the eye end of the rod is longitudinally adjustable so that the rod and cable can ride inside the outer metal sheath to provide support against bending loads. The length adjustment nuts on the rod-eye end were found adjusted all the way down so that the cable to rod swage point was outside the sheath at the full rich mixture setting. Metallurgical examination of the cable found that it failed in fatigue due to excessive and repetitive bending. According to the maintenance records, the mixture control cable was replaced at the last annual inspection on June 2, 1998, 99 hours prior to the accident. No other anomalies were found with the engine or its related systems.
On April 5, 1999, at 0950 hours Pacific daylight time, a Cessna 210D, N2340F, collided with ground obstructions during a forced landing in the Santa Fe Dam Recreation area near El Monte, California. The forced landing was precipitated by a loss of engine power during cruise. The aircraft, owned and operated by the two pilots on board, sustained substantial damage. The two private pilots, the sole occupants, sustained minor injuries. Visual meteorological conditions prevailed for the cross-country personal flight conducted under 14 CFR Part 91 of the Federal Aviation Regulations. A visual flight rules flight plan was filed for the flight, which originated at the Bracket Airport, LaVerne, California at 0930, with a destination of Santa Maria, California. According to the pilot's verbal and written statements, the aircraft had reached a cruise altitude of 8,500 feet over the Irwindale, California, area when the engine smoothly quit. The pilot contacted the El Monte Federal Aviation Administration (FAA) Air Traffic Control Tower, reported the power failure, and said he needed to land. The local controller provided the weather information and cleared the flight to land on any runway. Shortly thereafter, the pilot radioed that he would not make the field and landed in a dry wash area of the Santa Fe Dam Recreation area. During the gear up landing, the aircraft collided with trees and an embankment. The airframe and engine were examined by the Safety Board on April 8th following recovery of the aircraft. The mixture control cable was found fractured and disconnected from the cable's rod-eye end, which was still attached to the mixture arm of the fuel metering unit. The break in the cable was at the engine rod-eye end of the flexible cable at the point where the cable is swaged onto the rod. A metal outer sheath slides over the rod and the eye end of the rod is longitudinally adjustable so that the rod and cable can ride inside the outer metal sheath. The length adjustment nuts on rod-eye end were found adjusted all the way down so that the cable to rod swage point was outside the sheath at the full rich mixture setting. The fuel system was examined from the wing tanks to the engine. No staining was evident at any fitting examined. Each fuel tank's underwing and filler cap vent was checked and found unobstructed. No rust stains were found around the filler ports. No foreign objects or other debris were found during internal examination of the fuel tanks. The fuel quantity sending units were intact and free to move. A suitable replacement propeller was obtained and installed on the engine. A rod was connected to the fuel metering unit mixture arm to substitute for the broken control cable. A fuel supply was plumbed into the right wing root forward fuel feed line. Prior to engine start, electric boost pump operation was verified. Utilizing the aircraft systems, the engine was started and accelerated to 1,800 rpm (a broken engine mount precluded a higher power run). The engine was smooth and a magneto check produced a smooth 100-rpm drop. The mixture control cable was sent to the Safety Board's Materials Laboratory for metallurgical examination. The flexible cable was made up of seven inner wires surrounded by a spiraling outer cable wire. The fractures in all seven of the inner wires and the outer wire wrap exhibited arrest marks consistent with fatigue cracking which initiated on the inner diameter of the spiral outer wire, and, on each side of the inner wires. A complete report of the metallurgical examination is appended to this report. The maintenance records were reviewed. The mixture control cable was replaced at the last annual inspection, which occurred on June 2, 1998, 99 hours prior to the accident. The mixture control cable unit was marked S1220-3A AR37-97. The 37-inch-long cable was made up in 1997. Cessna Aircraft reviewed their internal engineering documents and could not find the designed length for the mixture control cable for the Cessna model 210D.
A loss of engine power due to the fatigue failure of the mixture control cable, which was due to the improper installation and adjustment of the cable 99 hours prior to the accident.
Source: NTSB Aviation Accident Database
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