49 CFR 175.88 - Inspection, orientation and securing packages of hazardous materials.
(a) A unit load device may not be loaded on an aircraft unless the device has been inspected and found to be free from any evidence of leakage from, or damage to, any package containing hazardous materials.
(b) A package containing hazardous materials marked “THIS SIDE UP” or “THIS END UP”, or with arrows to indicate the proper orientation of the package, must be stored and loaded aboard an aircraft in accordance with such markings. A package without orientation markings containing liquid hazardous materials must be stored and loaded with top closure facing upward.
(c) Packages containing hazardous materials must be secured in an aircraft in a manner that will prevent any shifting or any change in the orientation of the packages. Packages containing Class 7 (radioactive) materials must be secured in a manner that ensures that the separation requirements of §§ 175.701 and 175.702 will be maintained at all times during flight.