Building Resources

Zenith Air
Technical Support

Zenith Aircraft Company
1881 Airport Road, Mexico Memorial Airport
Mexico, Missouri, 65265  USA. 
Tel: 573-581-9000 (Mon - Fri, 8-5 Central)

Roger - Technical Advisor

Hardware Supplies


hTere are two common type of lock nuts (stop nuts). AN363 are all-metal and should be used on the engine side of the firewall. AN365 lock nuts have an elastic nylon insert and should not be usedanywhere on the engine side of the firewall or anywhere on the engine or inside the cowl as the elastic nylon material can be degraded by heat. 

Seems I recall that AN363 nuts should be considered one-time use and then discarded. AN365 can be re-used if they maintain torque specification, but all of these nuts are so cheap I wouldn't re-use them in critical applications. For instance, my Sensenich wood prop uses AN365 nuts and I discard them after one use ... a prop is definitely a "critical application!"  Kitplanes has an excellent article on this subject.