CHI06LA072

The airplane was substantially damaged when it struck trees and terrain during a forced landing following a loss of engine power. The pilot reported that he obtained a weather update and that the weather consisted of light snow, and forecast icing conditions below 10,000 feet. He also stated that the "potential icing conditions did not suggest the flight could not be safely conducted." About 20 minutes into the flight, while at cruise power and approximately 7,000 feet, the airplane began to lose manifold pressure and the engine began to sputter. He was " losing power, losing airspeed and losing altitude." The pilot applied full carburetor heat but the loss of engine power persisted. He subsequently executed a forced landing in a wooded area and he could not find a clearing during the forced landing attempt. During subsequent examination of the airplane, the right magneto would not produce spark. Disassembly revealed that the contact point would open and close when the magneto was rotated. The spark plugs were black and sooty. The air filter element was found to be wet and water could be wrung from it. Water was also in the filter housing. The carburetor heat control was found in the off position. A Federal Aviation Administration Advisory Circular (AC) stated that impact ice forms when moisture-laden air at temperatures below freezing strikes and freezes on parts of the airplane. The AC further stated that pilots should be particularly alert for such icing when flying in snow, sleet, rain, or clouds and that it is usually preferable to use carburetor heat or alternate air as an ice prevention means, rather than as a deicer, because fast forming ice which is not immediately recognized by the pilot may significantly lower the amount of heat available from the carburetor heating system. The weather conditions at the airport nearest the accident site included light snow, freezing fog, a temperature of -1 degree Celsius, and a dew point of -3 degrees Celsius.

History of flight

On January 24, 2006, at 0847 eastern standard time, a Piper PA-32-260, N3946W, piloted by a commercial pilot, was substantially damaged when it impacted trees and terrain following a reported loss of engine power near Jackson, Michigan. The pilot was diverting to the Jackson County Airport-Reynolds Field (JXN), Jackson, Michigan, when the accident occurred. The 14 CFR Part 91 flight was operating in instrument meteorological conditions and was on an instrument flight rules flight plan. The pilot received serious injuries. The aircraft departed the Capital City Airport, Lansing, Michigan, at 0819, and was en route to the Griffing Sandusky Airport, Sandusky, Ohio.

The pilot reported that he obtained a weather update and completed a pre-flight inspection of the airplane. He indicated that the weather consisted of light snow, and forecast icing conditions below 10,000 feet. He stated that the "potential icing conditions did not suggest the flight could not be safely conducted."

He stated that about 20 minutes into the flight, while at cruise power and approximately 7,000 feet, the airplane began to lose manifold pressure and the engine began to sputter. He stated that he was " losing power, losing airspeed and losing altitude." He stated that he applied full carburetor heat but the loss of engine power persisted. He stated that he followed the emergency procedures as to the loss of engine power in-flight. The pilot reported that he informed air traffic control (ATC) of his loss of engine power and declared an emergency. He was informed by ATC that JXN was the nearest airport. The pilot reported that he realized that he was not going to make the airport and subsequently executed an off-airport landing. He stated that he could not find a clearing during the forced landing attempt.

Personnel information

The pilot held commercial pilot and certified flight instructor certificates with single-engine land, multiengine land, and instrument airplane ratings. The pilot also held a second-class medical certificate issued on May 11, 2005. The medical certificate listed no limitations.

The pilot reported having a total of 803.0 hours of flight experience, including 90.9 hours in the same make and model as the accident airplane.

Aircraft information

The airplane was a 1967 Piper PA-32-260, Cherokee Six, serial number 32-895. The airplane was a low-wing monoplane configured to seat six occupants. The airplane was predominately aluminum in construction and was powered by a carbureted Lycoming O-540-E4B5 engine.

A review of the airplane's maintenance records revealed that the most recent airframe annual inspection was completed on April 1, 2005, and the most recent engine annual inspection was completed on April 18, 2005. The entries did not indicate the aircraft or engine time as of that date. The recording tachometer read 7,583.37 hours at the time of the accident. A maintenance entry dated May 31, 1994, indicated the installation of an overhauled engine at a recording tachometer time of 6,808.57 hours.

Meteorological information

At 0844, the weather at JXN, about 5 miles southwest of the accident site, was: winds 210 degrees at 14 knots gusting to 19 knots; visibility 1/2 statute mile in light snow and freezing fog; sky condition 1,200 feet broken, 1,600 feet overcast; temperature -1 degree Celsius; dew point -3 degrees Celsius; altimeter setting 29.61 inches of Mercury.

A review of weather radar data images revealed the accident location to be in an area of light to moderate precipitation at the time of the accident.

Communications

The pilot reported that he was in communication with air traffic control (ATC) when the airplane's engine began to lose manifold pressure. The pilot reported that he declared an emergency and was told by ATC that JXN was the nearest airport. Transcripts and recordings of the communications were not obtained in conjunction with this investigation.

Wreckage and impact information

The airplane came to rest in a wooded area about 5 miles northeast of JXN. The left and right wings of the airplane were partially separated. The leading edge of the left wing exhibited crushing at the location ahead of the left main landing gear. The leading edge of the right wing exhibited crushing at the location outboard of the right main landing gear.

The airplane was removed from the accident site and placed in the aircraft owner's hangar. Examination of the wreckage was conducted on January 31, 2006. Present at the examination were representatives of the Federal Aviation Administration, The New Piper Aircraft Company, and Textron Lycoming.

Examination of the airframe confirmed the presence of all of the flying and control surfaces. The wings were detached from the fuselage.

Examination of the control system revealed that all of the control system breaks had signatures consistent with overstress, or were deliberate cuts to facilitate removal of the airplane from the accident site. The flaps were in the up position and the flap handle was down. No pre-impact anomalies were found with respect to the control system.

The fuel selector valve was found positioned to draw fuel from the right main tank. Fuel was found in the fuel lines and the selector valve/sump.

The engine remained attached to the airframe and the propeller remained attached to the engine. One of the propeller blades was bent aft near its mid-span. The other propeller blade was bent aft near the tip.

Examination of the engine confirmed valve train, accessory, and crankshaft continuity. The engine was rotated and each cylinder produced "thumb" compression as the engine was rotated. The oil sump and carburetor filters were examined and found to be free of contamination. The left magneto produced spark from all leads when the engine was rotated. The right magneto did not produce spark when rotated by hand. The right magneto was partially disassembled and the contact points were found to open and close. The spark plugs were removed and exhibited a black sooty appearance. The carburetor air filter was found to have water in the filter element. When removed, several cubic centimeters of water were wrung from the filter element. Water was also found within the filter housing. The carburetor heat control valve was found in the cold position. The carburetor heat selector within the airplane cockpit was found in the cold position.

Tests and research

FAA Advisory Circular (AC) 20-113, entitled "PILOT PRECAUTIONS AND PROCEDURES TO BE TAKEN IN PREVENTING AIRCRAFT RECIPROCATING ENGINE INDUCTION SYSTEM AND FUEL SYSTEM ICING PROBLEMS", states:

"Impact ice is formed by moisture laden air at temperatures below freezing, striking and freezing on elements of the induction system which are at temperatures of 32 degrees F. or below. Under these conditions, ice may build up on such components as the air scoops, heat or alternate air valves, intake screens, and protrusions in the carburetor. Pilots should be particularly alert for such icing when flying in snow, sleet, rain, or clouds, especially when they see ice forming on the windshield or leading edge of the wings. The ambient temperature at which impact ice can be expected to build most rapidly is about 25 degrees F., when the supercooled moisture in the air is still in a semiliquid state. This type of icing affects an engine with fuel injection, as well as carbureted engines. It is usually preferable to use carburetor heat or alternate air as an ice prevention means, rather than as a deicer, because fast forming ice which is not immediately recognized by the pilot may significantly lower the amount of heat available from the carburetor heating system. Additionally, to prevent power loss from impact ice, it may be necessary to turn to carburetor heat or alternate air before the selector valve is frozen fast by the accumulation of