They do have MOS-designated Aircraft Maintenance Officers, but they are usually at the MALS (Marine Aviation Logistics Squadron) or the AIMD (Aviation Intermediate Maintenance Department). 9 times out of 10, they're not pilots, but they're usually mustangs, and some have aircrew experience as an E.
The MALS/AIMD are the next higher level of maintenance, roughly comparable to "back shops" in the AF.
Every USN/USMC flying squadron has a QA shop; this is part of the NAMP (Naval Aviation Maintenance Program). It's generally staffed by at least one person from each specialty within the maintenance dept., and they're not shitbags (most of the time). They're mostly SNCOs, and the QA Chief is usually a Gunny/CPO or MSgt/SCPO (E-7 or E-8, for those unfamiliar with USN/USMC enlisted rank structure). The QA Chief is directly responsible to the Commanding Officer on all matters related to Quality Assurance, and it's a rare instance when a CO does not listen carefully to his QA Chief.
There's a shit-load more detail I could get into, but I'll save it for another thread...
edit: added multi-quote.