19980909022849A

(.4) The float equipped airplane was attempting to cross a mountain pass, following two other company airplanes. The first two pilots, and passengers, described five to seven miles visibility, 700 feet ceilings, clouds hanging on the mountainsides, and misty rain. The route of flight required several turns in the pass. The pilot had not flown through the pass in marginal visual flight rules (VFR) weather before this flight. After the first two airplanes went through the pass, they lost radio contact with the accident pilot, and did not see or hear from him again. The wreckage was later located at the head of an intersecting canyon, two miles before the correct pass. The airplane had been modified with a short take off and landing (stol) kit. Canadian certification flight tests had determined that this modification eliminated aerodynamic warning of impending stalls, and therefore required an audible stall warning. Company pilots indicated it was common for the stall warning system to activate at an airspeed 10-15 miles per hour above the actual stall. At the time of the accident, the airplane did not have the ventral fin installed, and a takeoff flaps setting was selected. The audible stall warning circuit breaker was found in the pulled (disabled) position. (-23) on September 9, 1998, at approximately 1045 Alaska daylight time, N1433Z serial number 595, a Dehavilland DHC-2 float equipped airplane sustained substantial damage when it impacted the ground in mountainous terrain at about the 3,600 foot MSL elevation. The accident occurred approximately 58 statute miles NE of port alsworth, Alaska near telequana pass, in the neacola mountains. The pilot and four passengers received fatal injuries. Rust's flying service conducted the flight, based at lake Hood seaplane base at Anchorage, Alaska. Operating under 14 CFR part 135 as an on demand air taxi, transporting hunting clients to a camp located on the hoholitna river, approximately 190 statute miles west of Anchorage, Alaska. The pilot filed a company VFR flight plan and visual meteorological conditions prevailed at the time of departure from lake Hood. The aircraft impacted the ground in a nose down attitude in a boxed canyon about 2 miles north of telequan pass. Statements from two other company pilots flying ahead of N1433Z indicated ra dio contact among the aircraft. The lead aircraft lost radio contact with the pilot of N1433Z as they transited through telequana pass. The pilot of N1433Z followed the other aircraft approximately four miles back. The two lead pilots stated weather as 4,500 foot ceiling and visibility of five miles and mist while transiting telequana pass.