"Blow Out," the latest Brian De Palma thriller, creates problems for itself. Although characteristically stylish and intriguing, the movie, opening today at area theaters, falls short of the standards set by "Carrie" and "Dressed to Kill." After springing a few damaging leaks, "Blow Out" obliges De Palma to ride the rims of a shaky scenario with increasing desperation.

The picture seems to overshoot that shadowy point of diminishing returns where De Palma's pictorial sophistication and experimentation no longer compensate for patchiness in his plots. Unlike the smooth, streamlined "Dressed to Kill," "Blow Out" begins losing momentum and lurching out of control as De Palma tries to maneuver a contrived, tense resolution. He can't bring it off this time around, and perhaps the course itself has grown too familiar to both the filmmaker and his public.

John Travolta, who had his first significant move role in "Carrie," playing opposite Nancy Allen, now his costar in "Blow Out," proves an admirable choice for the young hero, a movie sound-effects specialist who happends to witness an auto accident that takes the life of a prominent politician. Recording woodsy natural sounds for a low-budget horror feature, "Co-Ed Frenzy," a "Friday the 13th" clone astutely parodied by De Palma in the prologue, Travolta hears a blowout and watches an approaching car lose control and crash. He dives in and succeeds in rescuing one of the two passengers trapped in the submerged car -- a young woman of dubious morals but gauchely appealing personality portrayed by Allen.

At the hospital Travolta learns that the passenger he couldn't save was a politician considered a front-runner in upcoming presidential primaries. Evidently, he picked up his traveling companion at a rally earlier in the evening. At the urging of one of the victim's friends, Travolta agrees to conceal the significant aspects of wht he witnessed and did at the accident site, in hopes of sparing the grieving family the additional painof a scandal.

Nevertheless, Travolta is haunted by a sound his trained ear detected an instant before the accident. Replaying the tape confirms his impression that an earlier explosive sound, which he believes to be a rifle shot, preceded the sound of the blowout. Another witness suddenly materializes, a suspiciously opportunistic sleaze (played by Dennis Franx, who was the cop in "Dressed to Kill") possessing photographic evidence of the accident, which he's sold to a newsmagazine. The stills in the magazine convince Travolta that there was foul play. He creates a short animated film of the accident by joining illustrations cut from the magazine with his tape recording. As far as he's concerned, this ingenious documentary fragment constitutes conclusive evidence that the car's tire was shot out.

Taking a bit from Chappaquiddick, Dallas and Zapruder's footage of the 1963 Kennedy assassination, De Palma adds deductive techniques suggested by "Blow-Up" and "The Conversation" to produce an astute fictional synthesis. Considering the familiarity of the sources, it's surprising how fresh and self-contained his case appears to be.

Unfortunately, De Palma seems to run out of effective mystery devices at about the halfway point. During the accident we're allowed a fleeting glimpse of an eyewitness who can't be seen by Travolta. After the hero completes his documentation, this murky character is brought front and center.

Once this villain, a loose, conspiratorial cannon who suggests a half-facetious, half-menacing version of Gordon Liddy, is out in the open, there's precious little mystery left for the audience. Of course, De Palma didn't try to fake out the audience with an abundance of suspects in "Dressed to Kill," but at least he observed the amenities right up to the denouement.

Travolta's efforts to persuade the authorities that his film reconstruction has merit lose significance when the focus shifts to the villain's busy sabotage campaign. One of the ingenious things about the clip is that it might not appear conclusive to an "expert" who didn't share the privileged vantage points of hero and audience.

All that seems beside the point after the potential resistance or conspiracy dwindles down to a one-man show staged by a remorseless psycho. The villain proves so adept at breaking-and-entering, tampering with evidence and luring the amateur detective team of Travolta and Allen into traps that the credibility of the film clip ceases to matter.

Moreover, this shift tends to leave one unprepared for a drastic denoubment and a curiously vicious kicker. The circumstances don't justify anything drastic, and the kicker appears to violate everything we've come to know and like about the characters played by Travolta and Allen, who achieve a shy, sweet-tempered rapport that contrasts radically with the filthy-rotten number they did in "Carrie." Given this appeal, I think moviegoers may be slightly miffed at De Palma for failing to be sufficiently protective of characters they feel protective about.

The breakdowns and miscalculations in the story may reflect an underlying frustration in De Palma himself, a desire to concentrate on exposition and characterizaton in ways foreclosed by made-up crime plots. For example, there's a flashback sequence about Trvolta's undercover work with the police that suggests the filmmaker is still obsessed with a project denied him, the movie version of Robert Daley's "Prince of the City." De Palma now hopes to do a film based on the 1969 Yablonsky murders, in which a mine unionofficial engineered the killing of a rival and members of his family. It would appear to be an astute choice of subject. Judging from "Blow Out," Brian De Palma may be in danger of burning himself out on murder cases inventd strictly for the movies.