NTSB Factual Report

HISTORY OF FLIGHT

On October 11, 1993, at 1337 central daylight time, a Cessna R182 airplane, N6422S, struck trees while maneuvering and fell to ground near Herbster, Wisconsin. The commercial pilot and passenger were fatally injured. The airplane was destroyed by collision with trees, a power pole and ground. Visual meteorological conditions existed for the personal flight. The airplane departed Eden Prairie, Minnesota about 1130 to stop at La Pointe, Wisconsin, then return. No flight plan was on file; the flight operated under 14 CFR 91.

The flight purpose was to view and photograph fall colors while flying to and from Madeline Island (La Pointe). The wife of the pilot stated he and the passenger took sandwiches for a picnic on the island runway, two 35mm cameras and a video camera. A brother stated the pilot was interested in purchasing land or a cabin in the vicinity.

No one was found during the investigation who had seen the airplane at the island.

Witnesses observed the airplane flying west at low altitude. Witnesses east of the site reported loud, even engine sound. One of 3 witnesses at the western-most vantage point recalled uneven engine noise, then no apparent sound as the airplane approached with wings rocking from side to side. The airplane arrived about 1000 feet from the latter 3 witnesses, and about 40 feet above trees, when the engine accelerated and the airplane turned sharply right. The turn continued to the north-northeast, accompanied by continuous engine sound. The airplane flew away toward forested, rising terrain. The sole witness above recounted smoke from the airplane as it turned and flew out of his view, but he did not otherwise characterize it.

Witnesses recounted the sound of impact or explosion, and saw smoke above trees in the direction the airplane had flown.

PERSONNEL INFORMATION

The pilot held a commercial pilot certificate with instrument and multi-engine airplane ratings, issued in September 1989. An instructor pilot certificate (single-engine airplane) issued in August 1989 had expired. The pilot's logbook number 2, dating from August 1989, was available for the investigation. It recorded no instruction given and 1182 total flight hours. The pilot had 866 hours in single-engine airplanes, about 56 in the accident model. The flight log recorded a biennial flight review June 26, 1991 and an instrument competency check October 6, 1992. His last preceding flight recorded was August 17, in the accident airplane.

AIRCRAFT INFORMATION

The airplane was manufactured in 1980. The owner/operator, an aero club, purchased the airplane in 1991 and offered it for rental to club members. Fuel cost was included in the rental.

The nominal cruise speed for the model is 156 knots with 75 percent power at 7500 feet above mean sea level (MSL).

Fuel capacity was 92 gallons, with 4 gallons unusable. The airplane was fueled to capacity October 6 and flew 1.6 hours before the pilot's departure on the accident date. The operator estimated the airplane had 68 to 70 gallons of fuel at the pilot's departure.

A club member reported a nonspecific vibration in flight on August 25, 1993. Two test flights were flown to identify a vibration, which did not recur. There were no like reports on subsequent flights.

An annual inspection was accomplished October 6, 1993, at 3615.2 hours on the tachometer. The airplane operated 3.1 hours from inspection to the pilot's departure on October 11.

The engine had 1486 hours since overhaul, 3165 hours since new.

COMMUNICATIONS

No record was found of the pilot or aircraft N6422S contacting FAA flight service or control facilities before or during flight.

AIRPORT INFORMATION

The La Pointe airport on Madeline Island is an unattended field with no services available. The airport is 20 miles east of the accident site and 150 miles northeast of Eden Prairie.

WRECKAGE AND IMPACT INFORMATION

The accident site was on the east face of a low ridge covered by hardwood forest and extending northeast into Lake Superior. Site elevation was 712 feet MSL. Terrain rose in the direction of flight to a crest at 790 feet about a quarter mile northeast of the site. Wreckage scattered on all corners at the intersection of two unpaved roads.

The airplane entered treetops 50 feet above ground and travelled about 240 feet before ground impact on Lefty's Road, south of the intersection of Bark Bay Road. The wreckage cast 150 feet further, heading 035 degrees. Fragments of both wingtips and of plexiglass lay between tree entry and ground collision. Tree limbs were found obliquely cut, with traces of black paint on the hewn surface.

The left wing lay 50 feet beyond ground impact. The tail sat 75 feet from impact. The right wing lay in two pieces 100 feet from impact. Both wings bulged in the area of the integral fuel tanks and burned. The cabin doors and fragments of door frame lay among the wreckage and hung from trees. The lower fuselage lay inverted and heading southwest over the remains of the cabin; main landing gear appeared retracted and their downlock hooks undamaged. The cabin interior, controls, switches and indicators were consumed by fire. The nose gear actuator piston rod bent in a position between up and down. Flaps and actuator were retracted.

The engine lay forward and right of the cabin wreckage, with control cables pulled and parted. The carburetor separated from the engine and showed impact and fire damage. One propeller blade remained loosely in the hub. The opposite blade lay beside the road east of impact; the blade bent and twisted over a large radius, and had chordwise marks on its front face. Engine cowling thrown clear of the burn area had no oil wetting, soot deposit or heat damage.

The tachometer was found outside the burn area. Its rpm needle was at maximum scale clockwise (3500 rpm), and the hour window read 3620.0 hours. The landing gear selector was found separated from the wreckage, in the down position.

The airplane extremities and all flight control surfaces were accounted for in the wreckage. There was no evidence of birdstrike, in-flight collision or breakup before entry into the trees.

MEDICAL AND PATHOLOGICAL INFORMATION

The pilot held an FAA second class medical certificate with limitation for corrective lenses. He had been issued a waiver by FAA for defective distant vision on the basis of demonstrated ability. The FAA airman medical record contained no other remarkable medical history. The report of autopsy remarked no preexisting disease. Toxicological test results were negative for all tests conducted.

The autopsy was performed by the Office of the Medical Examiner, Ramsey County, Minnesota, on October 12, 1993. FIRE

Fire was confined to the wreckage vicinity. A fan-shaped area radiating from ground impact appeared singed. Within the fan, forest humus ignited in spots. The cabin and airplane fragments near the severed wings were damaged or consumed by fuel-fed ground fire. Aircraft fragments outside the area wetted by fuel showed no soot deposit or heat damage.

TESTS AND RESEARCH

The engine was removed and partially disassembled. The dual magneto was destroyed; leads to top spark plugs were burned and impact damaged. The engine driven fuel pump was separated at its mount and fire damaged. The engine was turned by hand and mechanical continuity demonstrated through the crankshaft to all valves and the accessory drives. Compression was generated at each cylinder. The oil suction screen contained a quarter teaspoon of carbon. The oil filter element was found charred on disassembly. Metal particles were not apparent in the oil screen or filter. Spark plugs were uniformly grey, without combustion deposit or mechanical damage. Exhaust baffles remained intact.

A separated mixture control shaft from the carburetor was examined to determine the nature of the apparent fracture. The fracture characteristics indicated overstress under bending load. The metallurgist's report of examination is appended.

A video tape found in the wreckage was placed in a substitute cartridge and viewed. It showed nothing of the airplane or the flight.

A partial roll of 35mm film found in the wreckage was developed. The leader and first dozen frames were missing. The remnant in the damaged film canister showed nothing when developed.

ADDITIONAL INFORMATION

Parties to the investigation participated in a discussion of findings before adjourning from the accident scene.

Wreckage was released to the owner's agent in Washburn, Wisconsin. The video tape and 35mm film were returned to the pilot's wife. The carburetor was returned to the owner's agent.

NTSB Probable Cause

FAILURE OF THE PILOT TO MAINTAIN CLEARANCE FROM TREES.