Query: When were the military leaders replaced after a scandal over failure to maintain its nuclear arsenal? 
Context: As a result, the USAF fleet is setting new records for average aircraft age and needs to replace its fleets of fighters, bombers, airborne tankers, and airborne warning aircraft, in an age of restrictive defense budgets. Finally in the midst of scandal and failure in maintaining its nuclear arsenal, the civilian and military leaders of the air force were replaced in 2008.