al test plug mistakenly left by a civilian subcontractor employee in a fuel vent of an E-8C Joint STARS ground surveillance aircraft after scheduled depot maintenance late last year led this aircraft to experience a ruptured fuel tank during in-flight refueling and an in-flight emergency during a mission in Southwest Asia on March 13, Air Combat Command announced yesterday. We learned of this incident in early April. ACC, in reporting the findings of its accident investigation board, said there were no injuries and the aircrew was able to return the aircraft safely to its forward operating location, but the rupture caused an estimated $25 million in damage. The AIB also found that the depot subcontractor employed ineffective tool-control measures and did not follow mandated procedures when employing the plug. Northrop Grumman, lead contractor for the Joint STARS fleet, issued a statement yesterday saying it takes the safety and performance of the E-8C fleet “very seriously.” Immediately following notification of the incident, it said it implemented corrective actions in concert with the Air Force and assembled an independent team of experts to review depot processes and procedures. Additional steps will be taken, the company said, following a thorough assessment and consultation with the Air Force. (AIB executive summary)