NTSB Factual Report

On August 4, 2006, at 1250 eastern daylight time, a Piper PA-25, N6471Z, was destroyed during a forced landing in Egg Harbor Township, New Jersey. The certificated commercial pilot was seriously injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local banner-towing flight conducted under 14 CFR Part 91.

According to the pilot, he took off from Dix Field Airport (ONJ6), Linwood, New Jersey, and circled the airport in preparation for picking up a banner. He picked up the banner, and flew the assigned route without experiencing any abnormalities with the airplane. The pilot then returned to a field to drop the banner, and reduced power as he initiated a descent to the field. Just prior to releasing the banner, the pilot increased the throttle to arrest the descent, and initiated a climb. As the pilot increased the throttle, he experienced "little or no positive reaction from the engine." He released the banner and the airplane continued to descend. The pilot prepared for a forced landing to the field, during which the airplane impacted a tree and caught fire.

A Federal Aviation Administration (FAA) inspector examined the airplane and engine after the accident. According to the inspector, the throttle was in the full forward position, the mixture control was in the full rich position, and the carburetor heat was in the "off" position. The throttle cables and carburetor linkages remained attached and operational. The carburetor fuel screen was removed and no contamination was observed. The engine crankshaft was rotated at the propeller, and valvetrain continuity and compression were confirmed to all cylinders. The magnetos sustained fire damage and could not be tested.

Examination of the maintenance records for the airplane revealed the most recent annual inspection was performed on May 26, 2006. Additionally, the most recent overhaul was performed on April 22, 2005.

The closest weather reporting station to the accident site was Atlantic City, New Jersey, about 6 miles to the north. At the time of the accident, the temperature and dewpoint were recorded as 34 degrees Celsius (C), and 22 degrees C, respectively.

Interpolation of an FAA carburetor icing probability chart revealed the conditions were conducive to carburetor ice at glide and cruise power settings.

According to the FAA-H-8083-25, Pilot's Handbook of Aeronautical Knowledge, "although carburetor ice can occur during any phase of flight, it is particularly dangerous when using reduced power during a descent. Under certain conditions, carburetor ice could build unnoticed until you try to add power...Therefore, if you suspect carburetor icing conditions and anticipate closed-throttle operation, adjust the carburetor heat to the full ON position before closing the throttle and leave it on during the closed-throttle operation." The Handbook additionally states, "Once a power loss is noticed, immediate action should be taken to eliminate ice already formed in the carburetor, and to prevent further ice formation. This is accomplished by applying full carburetor heat."

NTSB Probable Cause

The pilot's failure to utilize carburetor heat during the descent, which resulted in the formation of carburetor ice and subsequent engine failure. A factor in the accident was the carburetor icing conditions.