The 30-year-old, captaining a much-changed side at the Estadio dos Barreiros, hit both the post and the crossbar and saw Maritimo keeper Romain Salin block another effort on a frustrating evening for the Magpies in Madeira.
Midfielder Dan Gosling was also denied by an upright after Alan Pardew's men bounced back from a less than impressive start to their Group D campaign.
They were indebted to keeper Rob Elliot, playing just his second game for the club, for two early saves, and he got down well 20 minutes from time to keep out dangerman Sami's skidding strike, but he also needed the help of the bar when full-back Davide Santon headed Valentin Roberge's late header against it.
But having gone into the game with only two members of what would be considered his strongest starting line-up - Steven Taylor and Santon - Pardew will have been the happier manager with a point banked and key men rested ahead of Sunday's Barclays Premier League clash with Norwich.
Newcastle turned in a poor first-half performance at Everton on Monday evening before staging a concerted fightback, and they were little more impressive during the early stages of tonight's encounter.
They might have been behind with less than two minutes on the clock when David Simao found space on the left to send in a dangerous cross which was only just too strong for Heldon as he slid in.
Maritimo, who went into the game unbeaten in seven matches in all competitions to date this season, were simply too good and too slick for Pardew's weakened side during the opening 25 minutes and, had it not been for Elliot, could have been in serious arrears.
The former Charlton keeper pulled off a fine reaction save to keep out Sami's 11th-minute volley and then blocked with his legs after the striker had run clear of the visitors' defence.
But having endured a difficult start to the game, the Magpies gradually started to find their feet and went close to the opening goal on four different occasions inside four minutes.
Gael Bigirimana saw his 27th-minute corner tipped over by keeper Romain Salin as it threatened to dip under the crossbar and then French midfielder Romain Amalfitano had a goal-bound volley blocked after connecting with another Bigirimana corner.
But it was the woodwork which came to the Madeira side's rescue twice in quick succession with the Premier League side turning the screw.
Central defender Mike Williamson found the ball at his feet inside the penalty area and, when his shot was deflected, Shola Ameobi dived in to head the ball towards goal where it hit the post and was bundled away by the recovering Salin, who had initially been wrong-footed.
Gosling was denied by the opposite upright on the half-hour when his 25-yard drive thumped off the foot of the post with Salin beaten.
The game settled down as both sets of players regrouped, although the first half ended in controversy when Sami stumbled having looked to have got the better of Williamson and Steven Taylor.
And in the melee which followed, the ball was stabbed back to Elliot prompting fury from the home fans as their side appealed in vain for a close-range free-kick for a back-pass.
Shola Ameobi was desperately unfortunate not to score just two minutes after the restart when he capitalised on an error by Joao Guilherme to charge into the box and side-step Roberge before curling a shot past Salin, but on to the bar.
The striker was joined on the pitch by younger brother Sammy when he replaced Haris Vuckic after 53 minutes, and the pair combined well to set up Amalfitano within four minutes, although his shot was wayward.
However, the home side perhaps should have gone ahead with 59 minutes gone when Sami ran into space on the left and crossed for substitute Fidelis to blast a first-time effort just past the post with Elliot helpless.
But the senior Ameobi went close at the other end five minutes later, forcing another decent save from Salin after bamboozling Guilherme with his turn on to Santon's pass.
Maritimo became increasingly careless in possession as time ran down and it appeared that if there was to be a winner, it would be the visitors leaving with the points.
But the Magpies enjoyed a major escape eight minutes from time when Roberge connected with Rafael Miranda's flick-on and Santon somehow managed to smuggle the ball away with the help of the goal-frame, and Elliot saved unconvincingly from substitute Goncalo at the death.