user: Question: What is the max gross weight of the Robinson R-22?
Columns: ['Aircraft', 'Description', 'Max Gross Weight', 'Total disk area', 'Max disk Loading']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Robinson R-22', 'Light utility helicopter', '1,370 lb (635 kg)', '497 ft² (46.2 m²)', '2.6 lb/ft² (14 kg/m²)']
SQL:

assistant: SELECT "Max Gross Weight" FROM "Table" WHERE "Aircraft" = 'Robinson R-22';