Cessna 421C N345JB accident near Wichita, Kansas

Probable cause

The failure of line personnel to ensure that the airplane was serviced with the proper fuel. Contributing to the accident was the Federal Aviation Administration's approval of a Supplemental Type Certificate (STC) which allowed an improper fuel filler opening, and the complacency in non-standard fueling practices by fixed base operator (FBO) line personnel.

NTSB analysis

During initial climb, the air transport pilot reported a loss of engine power. Unable to return to a runway, the pilot elected to perform a gear-up forced landing to an open field. The twin-engine airplane was substantially damaged during the landing. A line person employed by the fixed base operator (FBO) incorrectly fueled the airplane with 80 gallons of Jet-A instead of 100LL. Two medium single-engine general aviation airplanes based at the FBO had been modified with turbo-prop engines requiring Jet-A fuel. The two modified airplanes were not required by Supplement Type Certificate to modify the fuel filler opening, allowing the airplane to operate with smaller fuel filler openings,which did not comply with certification regulations. Line personnel at the FBO discovered that by rotating the Jet-A nozzle and dispensing at a reduced pressure, Jet-A fuel could be dispensed without using the adapter. Despite having correctly fueled the accident airplane in the past, the line person mistook the accident airplane for one of the converted airplanes and dispensed Jet-A fuel.

Text from the NTSB. Open the NTSB docket for CEN09LA145 for the full record.