Chuck “Chubby” Cherwonowitz, is a rail thin military helicopter pilot with an ironic nickname, it's possible that earlier in his career he struggled with weight problems, which he overcame. A cautious man; Cherwonowitz doesn't care what kind of boots he wears, but he always keeps a spare pair of laces.
The Keepers Trilogy
Cherwonowitz flew Franklin Townsend and Spike to New Vegas to investigate the Ginza abduction. However, he was forced to let thim off short of their goal because the presence of Grimlock's private army made it too dangerous to try and sneak past them.
Note: Cherwonowitz was no the Blackhawk pilot attached to Franklin's operation. When Franklin's plane was shot down, Cherwonowitz was sent to pick him up and transport him to Vegas.
Scorpion M515 Helicopter
The Scorpion M515 helicopter Cherwonowitz pilots, unlike most vehicles in the Keepers Trilogy, is completely fictional. The Scorpion comes from the notoriously awful 1990 helicopter-jock film Fire Birds starring Nicolas Cage.
The Helicopter's description, with its distinctive split bubble window, leaves no doubt this is intended to be the same fictional make of helicopter.