To all wise and knowlegable RV builders, Mounting boost pump. Should I be using lock tight on all the bolts or are the lock washers good enough ? Bearcatr2800
As a general rule, I would use locknuts (AN365 or MS21042) instead of lock washers or locktite. I'd save locktite for blind holes or non-critical places where you have a regular hex nut for some reason.
Lock washers are good when you can't use a locknut. IE, you shouldn't use nyloc nuts firewall forward. But for a boost pump on the aft side of the firewall, I'd think nylocs would be fine.
True, there are places with blind holes; a lockwasher can work there. But you shouldn't generally be using them when you can put a nut on the back. The airplanes I deal with professionally prohibit them unless a special exemption is received.
IE, you shouldn't use nyloc nuts firewall forward. But for a boost pump on the aft side of the firewall, I'd think nylocs would be fine.
Not all locknuts have nylon, and there are all-metal locknuts available that are suitable for use in the engine compartment.
However, the boost pump isn't in the engine compartment, nor should it be mounting to blind (tapped/threaded) holes. Either a locknut or a nutplate (which also has locking features) would be more appropriate.
