There are several items that are generally not allowed to be packed in your suitcase during a flight. These items can vary depending on the specific rules and regulations of the airline and the country you are traveling to. Here are some common items that are usually not allowed in checked baggage:

1. Flammable substances and objects, such as fuel, combustible liquids, and aerosols.

2. Explosive materials, including fireworks, snap caps, and explosives.

3. Toxic substances and corrosive materials, such as acids, pesticides, and bleaches.

4. Sharp objects, such as knives, scissors, nail files, and screwdrivers.

5. Weapons and firearms, including imitation weapons and ammunition.

6. Large quantities of batteries, especially lithium batteries.

7. Drugs and illegal substances.

It is important to always consult the guidelines of your specific airline and the restrictions of the destination country before traveling. These rules can vary, so it is wise to prepare well and remove any prohibited items from your checked baggage to avoid problems at the airport.