Aircraft Landing Gear Systems Exposure to and/or storage near which of the following is considered harmful to aircraft tires? 1. Low humidity. 2. Fuel. 3. Oil. 4. Ozone. 5. Helium. 6. Electrical equipment. 7. Hydraulic fluid. 8. Solvents. a. 2, 3, 4, 5, 6, 7, 8. b. 1, 2, 3, 5, 7, 8. c. 2, 3, 4, 6, 7, 8.