The Washington Post has fact checked McCain's claim his first crash of a Navy plane was caused by engine failure. 

The Navy's accident report from the time, as found by the Post, reports pilot error was the only cause -- specifically, a failure to keep the plane's speed above its stall speed and perhaps including a distracted pilot.  As the new Rolling Stone profile shows, McCain has rarely been about straight talk and almost always concerned with making himself look good enough to enable his all-consuming, megalomanical ambition.

Here is the WaPo link:
http://voices.washingtonpost.com/fact-checker/2008/10/mccain_fudges_his_navy_record.html