ERA09IA326

An electrical fire due to the lack of a positive locking mechanism for the fuse retainer in the main fuse block, which resulted in voltage fluctuations that caused thermal damage to the avionics cooling fan. Contributing to the incident was the student pilot's inadvertent shutdown of the engine at low altitude.

Shortly after takeoff, when the special light sport airplane was climbing through an altitude of approximately 1,000 feet above ground level (agl), the certificated flight instructor (CFI) and the student smelled and saw electrical smoke in the cockpit. The CFI began a turn back to the departure airport, and declared an emergency to the air traffic control tower. The CFI, in the rear seat, and without access to the electrical switches or circuit breakers, asked the student in the front seat to "turn everything off except the radio." After they received clearance to return to the airport, the CFI asked the student to turn off the radio; the student turned off the radio and the master switch. Shortly thereafter, the CFI instructed the student to turn on the master switch and radio, but "they would not work," and when the student cycled the master switch, the engine ceased operation. The CFI stated that due to the low altitude at the time of the power loss, he focused on landing safely, and did not attempt to troubleshoot the situation or verify the student pilot's actions. The airplane landed uneventfully on a road. Post-incident examination and testing revealed that the main fuse block for the airplane's electrical system exhibited intermittent contact, which, due to the architecture of the electrical system, caused the airplane system voltage to peak at values 5 to 8 volts above the normal value of 12 volts. The over-voltage condition resulted in overheating and thermal damage to an avionics cooling fan. The fuse block was not intended for aviation applications, and was installed without a positive locking mechanism for the fuse retainer. After the incident, the airplane manufacturer issued a service bulletin that recommended safety-wiring the main fuse block fuse retainer in the closed position, and also incorporated that change into the production line. No electrical or mechanical mechanism that related the fuse block malfunction or the over-voltage condition to engine operation or failure was identified. After the fuse block and damaged cooling fan were replaced with new units, the incident airplane and engine functioned normally. It was likely that the student inadvertently and unknowingly shut down the engine when he attempted to comply with the CFI's instructions.

HISTORY OF FLIGHT On June 8, 2009, about 1143 eastern daylight time, an Iniziative Industrali Italian Sky Arrow 600 Sport special light sport airplane, N445SA, was undamaged following an in-flight electrical smoke event and complete loss of engine power, and a subsequent forced landing near Marietta, Georgia. The certificated flight instructor (CFI) and student pilot were uninjured. The instructional flight was operated under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed for the flight, and no flight plan was filed. According to the CFI, he and the student departed from runway 27 at Cobb County Airport-McCollum Field (RYY), Marietta, Georgia, on a cross-country check flight for the student. When the airplane was climbing through approximately 2,000 feet above mean sea level, which was approximately 1,000 feet above ground level (agl), both he and the student noticed the smell and appearance of electrical smoke in the cockpit. The smoke was described as being visually "light but perceptible" by the CFI. The CFI took control of the airplane, executed a 180 degree turn back to RYY, notified the RYY air traffic control tower (ATCT) of the situation, and of his intentions to return immediately. ATCT personnel queried whether he was declaring an emergency, and the CFI responded in the affirmative. ATCT personnel then cleared the airplane to land on runway 9, and began rerouting local air traffic that was operating on runway 27. According to the student pilot, the CFI, seated in the rear seat, and without access to the airplane ignition switch, electrical switches or circuit breakers, asked the student in the front seat to "turn everything off except the radio," which he did. After receiving the ATCT clearance to return to RYY, the CFI asked the student to turn off the radio. The student turned off the radio, and also turned off the master switch. Shortly thereafter, the CFI instructed the student to turn on the master switch and radio, but "they would not work." When the student cycled the master switch to the "OFF" position, and then back to the "ON" position, the engine ceased operation. According to the CFI, the power loss occurred at an altitude of approximately 800 feet agl. He determined that the airplane would be not be able to reach RYY, and opted to land on a road instead. In his written account, the CFI stated that after "considering emergency landing area options, I elected to exercise PIC [pilot in command] emergency authority and land on Hwy 41 South in the vicinity of Loring Road, Cobb County GA - with only 700 to 800 feet AGL to work with, this seemed the most appropriate course of action. In prioritizing my attention and actions from the point of engine failure to touchdown, and given our low altitude, precarious nature of the emergency landing area, and concern associated with a potential electrical fire, I did not engage in the application of any ancillary emergency procedures outside of managing aircraft energy state and flight path." The landing was uneventful, there was no ensuing fire, and neither the airplane nor any ground objects were damaged. PERSONNEL INFORMATION Federal Aviation Administration (FAA) records indicated that the CFI held airline transport pilot, commercial pilot, and flight instructor certificates. His flight instructor certificate had airplane single engine, multiengine, and instrument airplane ratings. He also held a ground instructor certificate with an advanced ground instructor rating. His most recent FAA first-class medical certificate was issued in December 2008, at which time he reported 10,000 total hours of flight experience. The CFI indicated that he had 100 hours of flight experience in the incident airplane make and model, and that his most recent flight review was accomplished in June 2009. According to the student pilot, he had accumulated approximately 24 total hours of flight experience, all of which were in the incident airplane make and model. The student pilot did not hold an FAA medical certificate; instead he used his valid state-issued driver's license in lieu of a medical certificate, as permitted by 14 CFR 61.303. AIRCRAFT INFORMATION According to FAA and operator information, the airplane was manufactured in 2007, and was equipped with a Rotax 912 ULS 100 horsepower engine. It had accumulated approximately 339 hours total time in service, and approximately 24 hours since its most recent conditional inspection in April 2009. The incident airplane was designed, manufactured and operated in accordance with the regulations and standards of the Light Sport Aircraft (LSA) category. LSA category aircraft were not certificated to Federal Aviation Regulations (FAR) Part 23 Airworthiness Standards, but were instead designed and manufactured in accordance with an industry consensus standard. Manufacturers of aircraft slated for airworthiness certification in the LSA category must manufacture the aircraft to the design requirements and quality system of the applicable consensus standard that have been accepted by the FAA, and published through a notice of availability in the Federal Register. To meet the intent of FAR 21.190, and to be eligible for a special airworthiness certificate for LSA category, applicants must present satisfactory evidence that the aircraft was manufactured and was found acceptable to the provisions of the applicable consensus standard. Evidence of acceptability was provided by the LSA manufacturer's statement of compliance, FAA Form 8130-15, attesting to compliance with the requirements of 21.190 of the FAR. METEOROLOGICAL INFORMATION The automated weather observation at the departure airport, about the time of the incident, included variable-direction winds at 4 knots, visibility 10 miles, scattered clouds at 2,800 feet agl, broken cloud layer at 5,000 feet agl, temperature 28 degrees C, dew point 17 degrees C, and an altimeter setting of 30.04 inches of mercury. WRECKAGE AND IMPACT INFORMATION According to information provided by the FAA inspector who responded to the incident, the landing location was approximately 3.6 miles west-northwest of the departure airport. An FAA airworthiness inspector was also present to examine the airplane. When the master switch was turned "ON", the sound of the battery relay activation was heard as expected, but no power was available to the airplane electrical systems. The master switch was cycled three more times, and the same results were obtained. The cover for the forward electrical compartment was removed to gain access to the airplane battery and circuit components located forward of the instrument panel. The primary circuit components in this area included relays, terminal junctions, and fuse blocks. A fuse block was an insulated housing which held a removable fuse, and was equipped with terminal accommodations for the associated airplane wiring. The "main bus line fuse," which was electrically situated between the battery and the main bus bar, was located in this compartment, just below the battery relay. The FAA inspector "reset" the fuse by opening and re-closing the cover on the fuse block, and when the master switch was placed in the "ON" position, electrical power was observed on the airplane. The engine was then started; start-up and operation were normal. The magnetos were checked, and they functioned and grounded out normally, which resulted in shutdown of the engine. The engine was re-started, but an over-voltage condition was noted when the fuse block was disturbed by hand, and the engine was then intentionally shut down using the ignition switch. With the master switch still "ON," it was observed that slight finger pressure on the fuse block cover resulted in voltage variations, including a complete electrical power interruption, in the airplane electrical system. The airplane was recovered from the