Plugged Up: When an airplane takes a weather beating
It may sound obvious, but if your airplane is stored outdoors and has been exposed to adverse or severe weather, extra attention should be given during preflight.
On January 29, 2000, a Cessna 150 was substantially damaged during a crash shortly after takeoff from Wiscasset Airport in Wiscasset, Maine. The pilot was not injured in the accident.
During the preflight inspection the pilot checked the fuel tanks, which looked to be about half full. As the pilot continued the inspection, he found the fuel drains "frozen stuck" and did not want to force them open. He drained about 6 ounces of fuel from the fuel strainer off the engine and found no visible contaminates. He also checked the fuel vent and determined it was open.
The pilot started the Cessna, taxied to the runway, and performed a runup. All indications were normal, so he back taxied on Runway 25 and made a right-crosswind takeoff. Just seconds into the flight, and at about 125 agl, the engine quit.
The pilot elected to land in a clear area at the end of Runway 25. During the landing, the left wing tip touched the ground, the nosewheel collapsed, and the right wing dug into the snow, causing the airplane to come to a stop.
The FAA inspector found fuel on board the aircraft and the fuel drains still frozen shut. The inspector gave the pilot permission to move the Cessna back to its tiedown spot and attempt to drain fuel from the fuel strainer. Later in the day, the pilot returned to find fuel leaking out of the left wing fuel vent. The temperature had warmed above freezing, and any ice blocking the fuel vent would have melted. The pilot had no difficulty draining fuel from the fuel strainer or the carburetor and found about 10 cc of water in the carburetor.
The pilot told the investigator that the airplane had been exposed to "three weeks of terrible weather, high winds, sleet, blowing snow, and very cold temperatures. Some of this precipitation found its way into the fuel tank vents and blocked them."
The NTSB determined the cause of this accident to be the pilot's inadequate preflight inspection.
This accident underscores the importance of a thorough preflight. Although it may not have been possible to detect ice in the fuel vent, the pilot should have been suspicious, given the condition of the drains. This accident could have been prevented if the pilot had waited for the temperature to warm above freezing, which would have enabled the ice to melt.
Accident reports can be found in ASI's accident database.