WPR10LA209

The pilot reported that he flew around the local area and was going to orbit his parent’s house before heading inbound for landing. He stated that he applied carburetor heat for the descent to 2,000 feet for his orbit. During the second orbit, he heard and felt the engine sputter, and then go to idle. He immediately leveled the wings, turned the airplane toward the airport, exercised the throttle, and reported to an air traffic controller that he was inbound for landing. When he did not get the expected engine rpm, he again applied carburetor heat. He slowed the airplane to the best glide speed, and again exercised the throttle. A rise in manifold pressure was noted, but not rpm, when he increased the throttle. After determining that he could not make the airport, he decided to land on a city street. He tried to avoid power lines and telephone cables in his flight path, but was unsuccessful. The airplane subsequently impacted the ground at a 35-degree nose down angle, skidded to a stop, and caught fire shortly thereafter. During a postaccident inspection of the engine, no anomalies were noted that would have precluded normal operation. The pilot stated that he completed a thorough preflight. The airplane had more than 1/2 tank of fuel in the left wing, and just over 1/4 tank of fuel in the right wing. The fuel gauges agreed with the visual inspection. A graph in the Federal Aviation Administration Special Airworthiness Information Bulletin (SAIB) CE-09-35 illustrated that the conditions encountered in this accident were at the boundary of the areas for serious icing for both glide and cruise power. Given the lack of any mechanical anomalies it is likely that the formation of carburetor ice resulted in the loss of engine power.

On April 16, 2010, about 1906 Pacific daylight time, a Cessna 182, N5318B, collided with wires during a forced landing at El Cajon, California. The owner was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The commercial pilot and one passenger sustained minor injuries; the airplane sustained substantial damage by impact forces and post crash fire. The local personal flight departed Gillespie Field, El Cajon, at 1825. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot (who also held a certified flight instructor (CFI) certificate) stated that he completed a thorough preflight. The airplane had more than 1/2 tank of fuel in the left wing, and just over 1/4 tank of fuel in the right wing. The fuel gauges agreed with the visual inspection. After departure, the pilot was cleared westbound through Montgomery Field, San Diego, airspace at 2,500 feet. Near the coast, he began a shallow descent to remain under a cloud. He turned southbound, and followed the coastline at 500 feet above ground level (agl). He flew around the local area, and then began heading back to Gillespie Field. He checked his fuel quantity; the left tank indicated between 1/4 and 1/2, and the right tank indicated slightly below 1/4. He knew that he had plenty of fuel for the remainder of his intended flight. The pilot stated that he transitioned through Montgomery airspace eastbound at 2,500 feet. Once clear of the airspace, he contacted Gillespie air traffic control tower (ATCT). He stated that he wanted to orbit the Mt. Helix area, and then head inbound for landing. He pulled carburetor heat and descended to 2,000 feet, and completed several shallow turns above his parent’s house. During the second orbit, the pilot heard and felt the engine sputter, and then go to idle. He immediately leveled the wings, turned the airplane toward the airport, began to exercise the throttle, and reported that he was inbound to the tower. When the pilot did not get the expected engine rpm, he pulled carburetor heat. He verified that both magnetos were on, the mixture was rich, the primer was in and locked, and that the fuel selector was still selected to the both position. He slowed to best glide speed, and again exercised the throttle. He noted a rise in manifold pressure, but not rpm when he increased the throttle. He switched the fuel selector from both to left only. When that did not produce any results, he switched to the right tank only. The pilot evaluated his altitude and location, and decided to request runway 35. The ATCT controller asked the pilot to make a 360-degree turn. He advised them that he was unable, and informed them of his situation. It soon became apparent that the pilot could not get the airplane back to the airport, and he decided to land on North Johnson Road. He observed no cars, but there were a lot of power lines and telephone cables. He intended to clear one set, and then quickly noseover to regain airspeed and get under the next set of wires. However, he did not see two lines that crossed the road where he intended to let the airplane down. One cable caught the underside of the aft fuselage; this ripped off the right end and trailing section of the horizontal stabilizer. The two poles holding up the wires fell over, and the wire snapped. He tried to maintain an attitude as nose high as possible. The airplane impacted the ground at a 35-degree nose down angle and skidded to a stop. After pulling his face away from the instrument panel, he noticed fire at his feet. Both the pilot and his passenger exited through the left door, and got away from the airplane, which became fully engulfed in flames a few minutes later. The National Transportation Safety Board investigator-in-charge examined the engine, and detailed examination notes are in the public docket. During the examination, no anomalies were found that would have precluded normal operation of the airframe or engine. The FAA published Special Airworthiness Information Bulletin (SAIB) CE-09-35 on June 30, 2009, regarding carburetor ice prevention. The SAIB noted that carburetor icing doesn't just occur in freezing conditions; it can occur at temperatures well above freezing temperatures when there is visible moisture or high humidity. It states that icing can occur in the carburetor at temperatures above freezing. Because vaporization of fuel, combined with the expansion of air as it flows through the carburetor (the venturi effect) causes sudden cooling, a significant amount of ice can build up within a fraction of a second. The SAIB contains a graph that illustrates the probability of carburetor icing for various temperature and relative humidity conditions. The conditions encountered in this accident (ambient temperature 61 degrees/dew point 50 degrees Fahrenheit, 68 percent relative humidity), were at the boundary of the areas for serious icing for glide power and cruise power.