WASHINGTON -- The Feb. 13, 2003, crash landing of a U.S. surveillance plane in Colombia that resulted in the executions of an American and a Colombian and the kidnapping of three American crew members was due to engine failure, according to an official summary of the accident investigation by the U.S. Southern Command, a spokesman said Monday. The problem was probably caused by heat damage to its turbine blades, the report said. A summary of the investigation into a second plane crash March 25 that killed three Americans does not list a cause, but notes that the pilots may not have seen an approaching ridgeline in the dark. From Our Advertiser Families of crew members who were killed or kidnapped in the two incidents said that the brief summaries reveal little new information and that they want more information on what happened. The spy planes were part of the Southcom Reconnaissance System, a U.S. intelligence-gathering operation on drug operations in Colombia. After the first plane crash-landed Feb. 25 after engine failure, American pilot Tom Janis and Colombian intelligence officer Luis Alcides Cruz were executed by guerrillas from the Revolutionary Armed Forces of Colombia, a drug-running insurgent group. Three Americans -- Keith Stansell, Thomas Howes and Marc Gonsalves -- were taken hostage and remain prisoners of the FARC, as the group is known by its Spanish acronym. Six weeks later, the second and remaining plane in the program crashed into a tree on a mountainside, killing its American crew: Ralph Ponticelli, James Oliver and Thomas Schmidt. No evidence of ground fire The accident summary from the second crash runs less than a half-page, double-spaced. It recounts findings about the circumstances surrounding the crash, but makes no conclusion about the cause. An earlier insurance investigation indicated that the pilots may have lost their bearings in the mountains at night. The crew was searching for their kidnapped comrades. The investigation summary says that "no evidence was found of the aircraft having been hit by ground fire" and that "the inspection revealed that the engine was operating normally at the time of the mishap." It notes that the accident occurred at night and that "the ridgeline is believed to have been masked by a taller range of mountains in the background, which did not permit the ridge to be seen against the sky." Family members critical Some family members have been critical of the lack of official information available from the government or the companies involved. Northrop Grumman subsidiary California Microwave Systems ran the program until shortly after the first crash, then transferred it to a newly created company, CIAO Inc., which continues to run a successor program in Colombia. Northrop Grumman spokesman Jack Martin declined comment on the reports. CIAO officials could not be reached for comment. Ponticelli's father, Louis Ponticelli of Hammond, said that he was disappointed and angry at the brevity of the report. "It's a bunch of gobbledygook," he said. "I'm not going to stand for this. I am going to demand the full report through the Freedom of Information Act." Albert Oliver of Hampton, Ga., whose son was killed in the second crash,said he had been hoping for a fuller accounting of the program's management. In November 2002, two pilots from the program resigned after writing their superiors that using a single-engine plane in the dangerous missions was risking a crash. "It was real short," Oliver said of the summary. "I didn't think they were going to tell us anything. I was still concerned, deeply concerned, as to who put those planes back in the air after those two pilots walked away." Thermal damage A copy of the investigation summary from the Feb. 13 crash was not immediately available, but according to Southern Command spokesman Steve Lucas, "The conclusion was there was thermal damage to the turbine (engine) blades, which seems to be the proximate cause of the engine failure itself. The investigation did not reveal any foreign objects or bullets in the engine." The Times-Picayune reported that the program had an undiagnosed in-flight engine failure in 2001 -- rare in the Cessna Caravans used in the program --and turbine blade damage was found in the program's other plane in late January 2003, shortly before the first crash. Gonsalves' wife, Shane Gonsalves, of Big Pine Key, Fla., said she had not received a copy of the summary but said the description of its contents did not surprise her and that she had expected it would be very brief. "They're not revealing very much," she said.