CORDLESS DRILL WARNING
Warning about the use of cordless electric tools during aircraft maintenance.
This follows a US Federal Aviation Administration report of a fatal hanger accident involving a brush-type cordless drill. An explosion and fire erupted when an aircraft maintainer loosened a fuel panel on a Cessna 414 from which the fuel had not been drained. It was not clear whether the explosion and fire occurred when fuel began to escape, or when the maintainer attempted to replace the panel screws. An FAA presentation says: "We can only speculate that maybe he was distracted and attempted to remove the fuel panel by mistake; all the underwing panels look the same on this aircraft and the fuel panels are not placarded." Brush-type electric motors make and break electrical connections mechanically, which can produce sparks and electrical 'noise'. The FAA stresses the need to use brushless tools certified as suitable for use in hazardous environments such as aviation. Brushless motors use electronic rather than mechanical switching, and thus avoid the risk of sparking.