On July 23, 1997, about 1330 eastern daylight time, a DeHavilland DHC-6-200, N491AL, operated by Skys the Limit, Montgomery, New York, was substantially damaged during a forced landing near Sussex, New Jersey. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed for the positioning flight which departed from Orange County Airport, Montgomery, about 1315. No flight plan was filed for the flight which was conducted under 14 CFR Part 91. The pilot reported that the airplane had previously been operated in South America under foreign registry. It was bought and ferried to Kansas City, Missouri, where it was registered in the United States, given a fresh annual inspection, and converted to a jump airplane. The pilot reported that although he had flown the DHC-6 about 140 hours, he had only flown this particular airplane about 6 hours. This included a positioning flight from Kansas City Missouri, to Orange Airport, Montgomery, New York, and then the flight to Sussex, during which the accident occurred. In the NTSB Pilot/Operator Aircraft Accident Report, the pilot stated: "...Upon arrival over the N.E. side of the Sussex area I radioed the Sussex UNICOM that I was presently at the ski hill area requesting the airport location and [was] informed it was 8 mi west. I came out of a slow 180 degree turn to stay on the 196 degree radial and approximately 10-15 seconds after the engines quit. I cycled the fuel selectors checked pumps on and set flaps and landed in the only available field in the area." On scene examination revealed that the pilot landed on an uphill slope and ground rolled into a line of trees. A tree limb penetrated the spar of the left wing about 4 feet from the tip. The investigation revealed that the airplane was equipped with low fuel quantity lights for the front and rear tanks, which were designed to illuminate when the fuel level reached 100 pounds in their respective tanks. The fuel selector was a 3 position switch with AFT TANK (Both engines fed from aft tank), NORMAL (Left engine fed from aft tank, right engine fed from forward tank), FWD TANK (Both engines fed from forward tank). In an interview, the pilot reported that he departed with a total of 800 pounds of fuel onboard, but he did not remember the spread between the front and rear tanks. He did not remember the fuel tank selected at the time of the power loss. He thought the gauges read about 200 pounds on the front tank, and 100 pounds on the rear tank when the double power loss occurred. He remembered his altitude as being about 2,000 feet MSL (Sussex Airport elevation 421 feet MSL). When the battery switch was turned on, both engine low fuel pressure lights illuminated. The forward tank indicated 210 pounds of fuel, and the low fuel quantity light was not illuminated. When the boost pump was turned on, the low fuel pressure light was extinguished. The aft tank indicated 30 pounds of fuel, and the low fuel quantity light was not illuminated. When the boost pump was turned on, the low fuel pressure lights would momentarily flicker off, and return to steady illumination on. Examination of the electrical wiring to the low fuel quantity light in the belly of the airplane revealed that when it was touched, it fell from the electrical connection. Corrosion was found on the end of the wire. When cleaned and reattached, the low fuel quantity light illuminated. At the request of the Safety Board Investigator-In-Charge, the rear fuel tank was drained and then fuel was added at known increments to check the fuel tank indication readings. With no fuel the gauge read 0; with 43.5 pounds of fuel on board it read 50 pounds; with 84 pounds of fuel on board, it read 110 pounds; and with 124 pounds of fuel on board, it read 140 pounds.