"There were some lucky breaks for me," Hartnell said. "The second one hits something while the goalie is behind the net, and the third one hits a stanchion, again with the goalie behind the net. They weren't the prettiest of goals, but I'll take them. It seems like right now, it's my time."
Hartnell, who also scored three goals on Jan. 10 in a win at the New York Rangers, got the Flyers even 3-3 just 54 seconds into the final period. Braydon Coburn's dump-in kicked off the back boards straight out in front.
Islanders goalie Rick DiPietro, who went back to play the puck, was caught out of the net as Hartnell sent a shot into the vacated goal.
"Ninety-nine times out of 100, I go behind the net like that, and the puck keeps going around the net or I stop it," DiPietro said. "It hit a stanchion, hit off my pad, and went right in front of the net."
Mike Richards added an insurance goal at 12:11, and Steve Downie also scored for the Flyers, 9-1-2 in their last 12 games.
Martin Biron earned his 17th win with 28 saves, bolstered by Hartnell's third NHL hat trick.
"It's funny," Flyers coach John Stevens said. "When you look back at the start of the year for Scotty, he had some unbelievable chances, and they didn't go in. Now, the puck seems to find him wherever he goes. I think we weren't very good in the first period, but he was the one guy I thought was terrific.
"He single-handedly tried to turn the game around for us. It's only fitting that he ended up getting the hat trick."
The Islanders, who had a 3-1 lead after 20 minutes, got goals from Richard Park, Josef Vasicek and Bill Guerin. New York has lost three straight home games for the first time this season, and dropped their third consecutive to the Flyers.
"It was a total team fall-apart," Islanders coach Ted Nolan said. "The score dictated the way we thought we were playing. Instead of protecting a 3-1 lead, we were trying to make it 5-1. We didn't pay attention to detail."
DiPietro stopped 27 shots.
New York was without half its regular defensive lineup. Radek Martinek sat out his 13th game with a bruised ankle. Brendan Witt missed his fourth due to a sprained ankle, and Chris Campoli was sidelined for the first time after injuring his shoulder in the Islanders' 3-1 win at New Jersey on Wednesday.
The Flyers brought in the NHL's best power-play unit and took advantage of the Islanders, the league's third-best penalty killers.
Hartnell gave Philadelphia a 1-0 lead at 5:21 of the first period. He missed on his first rebound try of Jeff Carter's shot, but found the puck and scored on his second attempt.
Park tied it 26 seconds later when he was sprung on a breakaway off a feed from defenseman Bryan Berard.
Vasicek beat Biron at 10:35 to give the Islanders a 2-1 lead. Stevens was so irate, he called his only timeout then and ripped into his team.
"We turned over way too many pucks to them at our blue line, and that's what they feed off of," Hartnell said. "They kept coming at us, and when Johnny called that time out, he brought it to our attention."
The Islanders stretched their lead to 3-1 when Guerin scored his team-leading 18th goal at 17:21 during a power play.
One of the turning points for the Flyers was killing a four-minute penalty that spanned the first and second periods.
"They didn't score on that penalty in the second, and we knew we had a chance," Flyers defenseman Derian Hatcher said. "We weren't happy with the first period, and I think it showed the character of the team to bounce back like that."
Downie closed Philadelphia's gap to 3-2 when he poked home a loose puck during a scramble at 5:04 of the second period.
Philadelphia's power play struck again to tie it. Hartnell got a fortuitous kick pass from Scottie Upshall as DiPietro came out to play the puck, and sent a shot into the open net at 13:00.
"I'd love it if I had Scottie's luck tonight," Guerin said. "It's just great timing. But you should be playing well enough that you should recover from that."
Notes: Flyers forward Simon Gagne extended his point streak to five games (2 goals, 3 assists). DiPietro earned his fourth assist of the season on Park's goal, tying him with Chris Osgood (2001-02) for the team record. ... The Islanders are scheduled to play three more Saturday home games this season, two against the Flyers.
