Tuesday, May 12, 2009
Should You Reset A Circuit Breaker?
Revisiting and revising old ways of doing things
|The NTSB says it’s time to rethink something most GA pilots learned early in their training: If a circuit breaker trips while you’re flying, it’s okay to reset it after allowing a minute or two for it to cool, even if you have no idea what caused it to trip and cut off electrical power to a particular circuit. |
The subject of leaving a tripped circuit breaker alone came up in the NTSB’s investigation of the July 10, 2007, in-flight fire and crash of a Cessna 310R operated by NASCAR (the National Association for Stock Car Auto Racing). The plane crashed en route to Orlando Sanford International Airport (SFB) in Orlando, Fla. The commercial pilot, an ATP-rated pilot and three people on the ground were killed. The Part 91 flight was on an IFR flight plan in visual meteorological conditions.
The commercial pilot was acting as pilot in command (PIC) for the personal flight, with the ATP-rated pilot acting as a “safety pilot.” NASCAR normally required an ATP-rated PIC, and an ATP-rated “safety pilot” allowed the commercial pilot to act as PIC. The plane departed Florida’s Daytona Beach International Airport (DAB) at 8:22 a.m., destined for Lakeland Linder Regional Airport in Lakeland, Fla.
At 8:32:49, shortly after reaching a cruise altitude of 6,000 feet MSL, the ATP-rated pilot contacted air traffic control to declare an emergency: “Smoke in the cockpit we need…to land at Sanford.” The flight was cleared to proceed directly to SFB and descend to 2,000 feet. The last radio transmission from the plane was received at 8:33:15. It ended abruptly and seemed to include the phrase, “Shut off all radios, elec[trical].” Investigators said this phrase was consistent with the checklist guidance for an in-flight fire or smoke emergency in the Cessna 310R’s POH
, which stated, “Electrical load—REDUCE to minimum required.” The last transponder reply was received at the time of the last radio transmission.
Primary radar returns that were recorded for another 90 seconds showed the plane maintaining a heading of about 150 degrees toward SFB. The last of these returns was recorded at 8:34:45. At that time, the Cessna was three miles northwest of SFB and descending through 1,200 feet AGL. The residential area in which the airplane crashed was about 0.7 nm west of the last primary radar return.
According to several witnesses, the plane was traveling “extremely fast,” was “very low,” and its wings were “rocking” as it descended. Just before impact, the 310R entered a “steep bank” and made a sharp turn to the west. Witnesses reported seeing smoke trailing from the airplane, and one person stated, “Smoke was trailing from the port side.”
Although much of the airplane was destroyed in the postimpact fire, investigators saw discolorations and soot deposits on parts that weren’t directly exposed to the postcrash fire. For example, the instrument panel’s deck skin showed signs of thermal damage. Localized areas of the underside of this component had discolored primer paint, patches of charred/bubbling paint and soot deposits. Also, the instrument panel’s glare shield, which is normally attached to the upper surface of the instrument panel’s deck skin, had thermal damage at the attachment point.
The cabin door was found 60 feet away from the main wreckage. It wasn’t burned, and its latching pins weren’t damaged. Numerous soot deposits, however, were noted on the door’s interior side. These deposits trailed across the door’s lower portion from an area that would have been near the instrument panel’s lower edge. The undamaged latching pins and the location and existence of a trailing soot deposit are consistent with the pilots having opened the cabin door to vent smoke during an in-flight fire.
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