The airport was closed for 2 1/2 hours Saturday morning after the incident.
A Romanian Transportation Ministry team arrived in Timisoara to investigate.
Foaming agents are used less often now than they once were for commercial aircraft that can't lower their landing gear, said Gideon Ewers, a spokesman for International Federation of Airline Pilots' Associations.
He said foam was used more widely in the 1940s and 1950s to prevent gasoline bursting into flames.
"It's quite unusual these days to get foam because jet fuel is much less volatile than gasoline that was used in piston engine airliners," he said in a telephone interview from London.
Previous similar incidents include:
-- Nov. 16, 2008: A US Airways Express Dash 8-300 with 38 passengers and crew slid along the runway in Philadelphia with its nose gear stuck. Fire crews spread foam as a precaution. No one was injured.
-- March 20, 1999: An Iberia airlines MD87 on approach to Geneva with 101 passengers requested foaming after its nose gear failed to lower. It landed smoothly.
-- Sept. 24 1997: An Olympic Aviation Dornier 228 with 19 people aboard carried out a successful emergency landing at the Tanagra air base near Athens after foam was spread on the runway.
-- Feb. 10, 1988, an Aeroflot TU-154 airliner with 166 people aboard skidded for about a mile (more than 1.5 kilometers) along the runway in Dushanbe, Kyrgyzstan, after a hydraulic failure. Foam was laid along the entire runway and no one was injured.
Despite its success in such incidents, the effectiveness of foaming continues to be debated within the aviation community. Some airport fire services consider it unnecessary, saying it provides little or no benefit.
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Associated Press Writer Slobodan Lekic contributed to this report from Brussels