Hyper-compressor

A hypercompressor is a crucial component of an aircraft. If it is broken, the aircraft will not work.

Use/Functionality
It is located near/in the engine of an aircraft. In Episode 12, it is shown that good hyper-compressors are rare and expensive. This is probably due to the fact that Sumire Kimura, the empress, banned the public sale of automobile parts-- supposedly to curb traffic problems.

However, as hyper-compressors are crucial for an airship to work, they are still in demand despite the high prices.