By MARIE BETANCOURT
And LIZ BALMASEDA Herald Staff Writers

Federal Aviation Administration investigators Friday checked the security system at San Juan's Isla Verde Airport, where a "very drunk" Cuban refugee slipped by Thursday with a toy gun, a hollowed-out Bible containing dummy sticks of dynamite, and a flask of flammable liquid - and later hijacked a Capitol Air DC8 to Havana.

After the hijacker, identified only as Armando, was arrested by Cuban officials, the 253 passengers of Flight 236 waited all night at Havana's Jose Marti International Airport and were flown to Miami early Friday morning aboard two jetliners.

The hijacking marked the third time Flight 236 was diverted to Havana, and it was the ninth successful hijacking of an American airplane to Cuba since May 1. Two other attempts were foiled by passengers who nabbed the would-be hijackers.

Robin Matell, a spokesman for Capitol Air, a discount airline based in Smyrna, Tenn., said, "We are concerned. We are still investigating the security system in Puerto Rico."

He would not release the name on the hijacker's plane ticket.

Meanwhile, FBI officials in Miami were trying to track the identity of the man whom passengers described as a slight, black Mariel refugee with slicked-back hair. They said he was 52 years old and wore an old, white jacket.

FBI officials in Miami said they planned to charge the man with air piracy.

The hijacker said he wanted to go to Cuba to see his seven children and his gangrene-stricken wife "before he dies," passengers said. He said he had lived in Miami until three months ago, when he went to Puerto Rico and worked at a service station.

The man rambled aloud, holding the fake dynamite under his arm. He had the toy gun in one hand and the flask in the other. As he waved the flask, the flammable liquid spilled near the cockpit of the plane, passengers said.

After the jetliner touched down in Havana, Nelson Perez, 33, a former Pompano Beach police officer, went against the pilot's orders and jumped the hijacker, tying his hands behind his back and holding him on the floor until the Cuban authorities took him.

Federico Bauzo, the general manager of General Aviation Services Inc., the security firm that screens Capitol Air passengers at Isla Verde Airport in Puerto Rico, defended his 6 "highly qualified" inspectors.

"Our records show that six pairs of scissors, one baseball bat and several half-consumed bottles of liquor were taken from passengers who boarded that flight Thursday," said Bauzo, whose firm is one of the two security companies at the San Juan airport.

The FAA plans to install special detection machines at the San Juan airport to spot bottles that could be filled with flammable fluids, said Atlanta-based FAA spokesman Jack Barker.

"This is not something the FAA is taking lightly," Barker said. "We don't want to turn the airports into a police state, but we are going to stop the hijackings. "

Thursday's ordeal aboard Flight 236 began at 7:15 p.m., when the senior flight attendant handed Capt. George Rogers, the pilot, two lengthy notes handwritten in Spanish.

"This plane is diverted to Cuba," one of the notes said in big letters, the FBI said.

Shortly before commandeering the plane, the hijacker was nervous, pacing about the cabin, asking what time it was and asking those around him to read him passages out of the Bible, passengers said.

"He was very drunk. There is no question the guy had a lot of booze in him," said Dick Gist, a passenger from Miami.

The hijacker went to a lavatory near the cockpit and emerged with his shirt doused in the flammable liquid.

"We could smell the fumes that's what convinced me that he wasn't playing around," said Rogers, the 38-year-old New York-based pilot who has been flying for the airline for seven years.

Passenger Isidor Torres, a 33-year-old Puerto Rico resident who translated for the flight crew, quoted the hijacker as saying: "I'm only going to give you 35 minutes to reach Cuba and then I'm going to blow up the plane."

An hour and a half later, the jetliner landed in Cuba, one of its tires blowing out on the wet runway. As Cuban authorities boarded the aircraft and questioned passengers, a Cuban television crew filmed the interviews.

"I've never experienced anything like that in my life. He kept saying he was going to blow up the plane if they didn't take him to Cuba," Torres said.

Many of the passengers, however, were not even aware of the hijacking until the pilot announced it over the speaker.

"When he said we were going to Cuba, the people thought it was a joke. We just couldn't believe it," said Maria Scarpati, of Puerto Rico.

As the plane landed, the hijacker dropped the fake explosives and broke down, passengers said.

The DC8 arrived in Miami with 125 of the passengers and the crew at 5:30 a.m. EDT. Twelve minutes earlier, a chartered Boeing 707, which had flown to Cuba with replacement tires, had returned the other passengers. The final destination of Flight 236 is Chicago.

The latest wave of hijackings has been attributed to homesick and desperate Mariel refugees. But the number of successful hijackings so far this year still falls behind a record number established in 1969, when 33 American planes were forced off route by air pirates.

This story was supplemented with material from Herald wire services.