The 12-17200 Thread Cleanout Tool is an aircraft spark plug thread cleaning and thread restoration tool used on 18 mm spark plug holes in piston aircraft engines (commonly Lycoming and Continental cylinders). It is designed to clean carbon buildup, corrosion, and debris from existing cylinder head threads without cutting or enlarging them.

The tool is engineered with a spring-loaded, self-centering design, allowing it to follow the existing thread path and restore thread condition safely during maintenance. It is widely used in aviation maintenance to prevent cylinder removal caused by damaged or contaminated spark plug threads.

Key features include:

Aircraft spark plug thread cleanout tool (18 mm)
Designed for piston engine cylinder head threads
Removes carbon, oxidation, and debris from threads
Spring-action design prevents thread enlargement
Matches spark plug thread geometry for safe cleaning
Used in Lycoming and Continental engine maintenance
Helps prevent costly cylinder head repairs or helicoil replacement
Fits standard aviation spark plug maintenance procedures
Common MRO tool for A&P mechanics
Reusable precision thread restoration tool