Albuquerque, NM, USA
N16WF
Forbes Rutan Long EZE
On final approach to the runway, the pilot lowered the landing gear and visually inspected it through the sight glass to make sure it was down and locked. About 20 seconds later, there was a sudden and total electrical failure and the engine lost power. The pilot switched from the MAIN battery to the AUX battery in an attempt to restore electrical and engine power, but left it selected for only about 2 to 3 seconds. He then switched back to the MAIN battery and concentrated on the emergency forced landing. He could not recall if the propeller was windmilling at the time (a windmilling propeller would be necessary to start the engine using AUX battery power). The pilot made a forced landing on an access road and collided with a wall causing substantial damage. The airplane was equipped with a dual electronic ignition system, not magnetos. A constant source of electrical power was required for ignition. In the event of an electrical power loss, the engine would lose power. An FAA avionics inspector said the 5-amp main fuse had opened, probably due to a shorted wire inside the master relay, resulting in an over-current condition. This caused the master relay to de-energize and cut power to the bus. The alternator, which was tested to 10.5 volt output, has a nominal output of 13.8 volts. Minimal output to charge the battery is 12.5 volts. The FAA inspector's statement noted that the cockpit-mounted master switch activated the positive side of the master relay solenoid. Standard industry practice was to wire the positive side of the master relay to the unfused input from the battery, and then switch the negative side using the master switch. Some commercially available solenoids have the positive terminal wired to the battery input.
On August 7, 2005, approximately 1110 mountain daylight time, a Forbes' Rutan Long EZE, N16WF, piloted by a commercial pilot, was substantially damaged during a forced landing at Albuquerque International Sunport (ABQ), Albuquerque, New Mexico. Visual meteorological conditions prevailed at the time of the accident. The personal cross-country flight was being conducted under Title 14 Code of Federal Regulations Part 91, and a VFR flight plan had been filed. The pilot was not injured. The flight originated at Henderson Executive Airport (HND), Las Vegas, Nevada, approximately 0720 Pacific daylight time. According to the pilot, the airplane was serviced with 24 gallons of 100LL fuel, for a total of 45 gallons, before departing Las Vegas. He said the planned flight would consume approximately 26 gallons of fuel. He departed HND approximately 0720 and climbed to his VFR cruising altitude of 9,500 feet msl. Approximately 8 miles from ABQ, he began a descent to traffic pattern altitude. Approximately 3 miles from ABQ, he slowed from 140 knots to less than 100 knots in order to complete the BEFORE LANDING checklist and lower the landing gear. When the airplane was on a 1 mile final approach to runway 08, he lowered the landing gear and visually inspected it through the sight glass to make sure it was down and locked. About 20 seconds later, there was a sudden and total electrical failure and the engine lost power. The pilot switched from the MAIN battery to the AUX battery in an attempt to restore electrical and engine power, but left it selected for only about 2 to 3 seconds. He then switched back to the MAIN battery and concentrated on the emergency forced landing. He could not recall if the propeller was windmilling at the time (a windmilling propeller would be necessary to start the engine using AUX battery power). Concerned that he might hit a fence at the approach end of the runway, the pilot elected to land on a nearby access road. After touching down, the left wing struck a cement retaining wall. The airplane pivoted to the left and the main landing was gear torn off. The airplane then collided with the curb and gutter. Postaccident inspection revealed the nose gear structural spars were buckled, the bottom fuselage skin and winglets were scraped and ground down, and the fuselage was buckled. The airplane was equipped with a dual electronic ignition system, not magnetos. A constant source of electrical power was required for ignition. In the event of an electrical power loss, the engine would lose power. According to an FAA avionics inspector who examined the electrical system, the 5-amp main fuse had opened, probably due to a shorted wire inside the master relay, resulting in an over-current condition. This caused the master relay to de-energize, and cut power to the bus. The alternator, which tested to 10.5 volt output, has a nominal output of 13.8 volts. Minimal output to charge the battery is 12.5 volts. The FAA inspector's statement noted that the cockpit-mounted master switch activated the positive side of the master relay solenoid. Standard industry practice was to wire the positive side of the master relay to the unfused input from the battery, and then switch the negative side using the master switch. Some commercially available solenoids internally wire the positive terminal to the battery input.
a total electrical failure due to a short in the master relay, causing the main fuse to open. Contributing factors included an inadequate electrical design by the airplane's builder, a low-output alternator, a cement wall, and unsuitable terrain on which to make a forced landing.
Source: NTSB Aviation Accident Database
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