ERA12LA058

According to the pilot, while the airplane was descending on final approach, the throttle control became unresponsive. Although multiple settings were attempted, the engine remained at idle rpm, and the pilot made a forced landing on a road. The airplane collided with a lightpost and sustained substantial damage to the fuselage. Although initial examination of the engine did not reveal any preimpact mechanical anomalies that would have precluded normal operation, further examination revealed that the throttle cable had separated from its housing/end fitting. As a result, the throttle cable could not actuate the carburetor control, and the engine remained at idle rpm. A review of the airframe and engine logbooks revealed that the throttle cable was not maintained correctly and was never maintained in accordance with the manufacturer’s service manual.

On November 1, 2011, at 1735 eastern daylight time, a Cessna 172N, N739JN, was substantially damaged during a forced landing following a partial loss of engine power while on final approach to Pompano Beach Airpark (PMP), Pompano Beach, Florida. The certificated commercial pilot and one passenger reported minor injuries. The personal flight was operating under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed. The flight originated from Fort Lauderdale Executive Airport (FXE), Fort Lauderdale, Florida, at 1730. The pilot stated that he was descending on final approach to land, when the throttle control became unresponsive. He made attempts to change the engine power setting, but no change in power occurred. The engine remained at idle speed as the airplane continued to descend. He made a forced landing on a road and the airplane collided with a light post. Post accident examination of the airplane by a Federal Aviation Inspector revealed that the fuselage collided with a light post and broke away from the cabin section. The left wing outboard section was broken away from the wing assembly at the wing strut. The wreckage was recovered and a cursory examination was conducted on the engine. No engine specific mechanical anomalies were discovered that would have precluded normal engine operation. Further examination revealed that the outer throttle cable housing was separated. When the throttle control was moved, it did not actuate the carburetor throttle control. A review of the maintenance records did not reveal any recent maintenance to the cable and during the last annual inspection no anomalies were noted. A review of the aircraft and engine logbooks revealed that the throttle cable was not replaced or inspected within the last 2512.9 hours. A review of the Cessna model 172 service manual states, on page 2-42, item J: “Engine controls and linkage-check general condition, freedom of movement through full range. Check for proper travel, security of attachment, and evidence of wear. Check friction locks for proper operation (every 50 hours).” Page 2-48 of the manual, special inspections legends, part E; states, “Lubricate each 50 hours, these controls are not repairable and should be replaced every 1,500 hours or whenever maximum linear movement exceeds .050 inches.”