Fire under the radar dome!
Our pilots were "getting back in the saddle," so we had FCLPs scheduled for the entire day. Topcat 705 returned from the first round of touch-and-go landings, and another aircrew was ready for a crew swap. The PC taxied the S-3B into spot and requested permission from the pilot to open the hatch. The new crew successfully completed the swap and started their preflight checklist. At that point, the COTAC signaled for an AME troubleshooter.
As the flight-line chief, I sent AME3 Nicolas Griess to find out what was wrong. The No. 1 engine was on line, and AE3 Eric Barber, a conscientious troubleshooter, was doing a pre-final check. As he bent down to verify that the forward avionics fan was operating properly, he quickly signaled a figure eight to the PC and to me, meaning the aircraft had a fire. I entered the cockpit and, calmly as possible, said, "Sir, secure electrical power and shut down; we have a fire under the radome!"
The acrid smell of an electrical fire filled the cockpit, but we still could not see smoke. Petty Officer Griess had been troubleshooting a forward avionics circuit breaker that would not reset. After properly securing the engine and APU, everyone quickly exited the aircraft.
Once clear of the aircraft, smoke was visible around the radome. The groundcrew quickly released the radome latches, moved to the windward side of the aircraft, and got ready to raise the dome. Airman Juan Tapia was standing next to the aircraft with a Halon fire bottle. It was charged and ready to go should flames be visible. When we opened the radome, oxygen was introduced to the fire triangle, and the fire erupted. Airman Tapia was ready, and he put out the fire with a two-second burst of Halon. This entire incident lasted only 60 seconds, from start to finish.
The culprit was the Kapton wire that led to the forward avionics fan. The wire had chafed and shorted on an Add clamp. When the troubleshooter tried to reset the circuit breaker, the wire arced and ignited the radar absorption blankets. We initiated a subsequent inspection of all other aircraft but didn't find any more discrepancies.
Looking back on the events of that day, I'm proud our training helped to prevent a more serious mishap. We were lucky, though, that the fire took place during a crew swap and not while the aircraft was in the air or taxiing. Had the short occurred while airborne, we could have lost the aircraft and possibly the crew. Airman Tapia did a great job, but he was injured slightly when a small Halon leak from the bail fitting burned his hand.
Everyone involved in this incident acted in a professional manner, didn't miss a beat, and prevented a potentially disastrous situation. Because of our team's quick reaction, the aircraft was damaged only slightly. We repaired Topcat 705, and it was flying again just a few days after the incident.
AMC(AW/SW) Rick Boswell, VS-31
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|Date:||Sep 22, 2005|
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