Boeing 757-222 N570UA incident near Denver, Colorado

Probable cause

There was a malfunction of the electronic engine control (EEC) burner pressure (Pb) sensor that had an abnormally high indication that resulted in an excessive amount of fuel being pumped into the engine that was still at a sub-idle condition. Because the engine was still accelerating to idle, the limited airflow through the engine engine was insufficient for the amount of fuel and resulted in a tailpipe fire. The cause of the EEC's Pb sensor fault could not be determined.

NTSB analysis

A United Airlines Boeing 757-222, N570UA, experienced a tailpipe fire on the No. 2, right, engine, a Pratt & Whitney PW2037(M) during engine start at the Denver International Airport. The airplane's right wing in back of the engine and adjacent fuselage suffered minor damage. Interrogation of the cockpit engine display showed several faults related to the electronic engine control (EEC) burner pressure (Pb) sensors. The interrogation of the cockpit engine display also showed the Pb indications were abnormally high for an engine start. Fuel is scheduled to the an engine as a function of Pb. So a high Pb indication would consequently result in a high fuel flow to the engine. Because the engine was just starting, the limited amount of airflow through the engine was insufficient for the excessive amount of fuel and resulted in a tailpipe fire. The EEC was removed from the engine and sent to the manufacturer for testing. The testing could not identify a cause for the malfunction and subsequent tailpipe fire.

Text from the NTSB. Open the NTSB docket for ENG09IA007 for the full record.