The T-558 is an aviation-grade deep spark plug socket designed for 18 mm aircraft spark plugs (7/8" hex), using a 1/2" drive interface for higher torque applications and heavier-duty ratchet use.

It is part of the standard Tempest aviation spark plug service tool family, commonly used in piston aircraft engine maintenance (Lycoming, Continental, etc.).

This version is the non-magnetic variant, meaning the spark plug is not retained inside the socket by a magnet, relying instead on precise socket fit and operator control.

Key features include:

1/2" drive aviation spark plug deep socket
Fits 7/8" (18 mm) aircraft spark plugs
Heavy-duty design for higher torque applications
Deep well construction for cylinder head access
Six-point internal geometry to prevent plug damage
Compatible with standard GA piston engine maintenance procedures
Used on Lycoming and Continental engines
Part of Tempest T55x / T56x spark plug tool system
Designed for professional MRO use (A&P mechanics)
Non-magnetic version (unlike T557-1 variant)