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N747TW accident description

Minnesota map... Minnesota list
Crash location Unknown
Nearest city St. Bonifacius, MN
44.905954°N, 93.744974°W
Tail number N747TW
Accident date 19 Sep 2001
Aircraft type Cirrus Design Corp. SR-20
Additional details: None

NTSB Factual Report

On September 19, 2001, at 0830 central daylight time, a Cirrus SR-20, N747TW, piloted by a private pilot, sustained substantial damage during a forced landing to a corn field near St. Bonifacius, Minnesota. Instrument meteorological conditions prevailed at the time of the accident. The personal flight was being conducted on an instrument flight rules plan under the provisions of 14 CFR Part 91. The pilot and passenger on board the airplane sustained serious injuries. The cross-country flight originated at Minneapolis, Minnesota, at 0755, and was en route to Rapid City, South Dakota.

In his written statement, the pilot said that 3-5 minutes after leveling off at 3,000 feet, a red oil light appeared on the instrument panel. The pilot said he looked over at the oil pressure gauge. It read zero pressure. The pilot said that the engine started missing. He contacted departure control and informed them he had an emergency with no oil pressure. The pilot said, "Departure asked if I wanted [the] ILS for Flying Cloud [Airport], which was 12-13 mile[s] away." The pilot said it was too far and decided to go for Waconia. The pilot said he set up for best glide airspeed and informed departure that he was still in the weather. The pilot said that at 2,000 feet, he noticed smoke begin to appear from the cowling. The pilot said he broke out of the clouds approximately 800 feet agl. He informed departure that he was looking for a landing area. The pilot said he set the airplane down in a cornfield, slid approximately 70 feet, and came to a stop.

Federal Aviation Administration inspectors examined the airplane at the accident site. The airplane was resting upright on its belly in a cornfield. A ground scar and broken cornstalks preceded the airplane wreckage for approximately 50 feet. The airplane's engine was broken aft at the mounts and resting inverted behind the trailing edge of the airplane's right wing. The nose gear was broken aft. The cowling was broken off at the firewall. The bottom right side of the cowling was broken aft. The bottom right side of the firewall was bent aft and upward 90 degrees. The bottom of the forward fuselage beneath the right front seat floor was crushed upward. The bottom right side of the forward fuselage was broken aft and inward beginning at the firewall and running aft 26 inches. Both main landing gear were broken aft. A hole was punctured in the left wing at the fuel tank. The propeller remained attached at the flange. One of the three propeller blades was bent aft. Flight control continuity was confirmed. The wing flaps were up.

An examination of the engine revealed 3 punctures in the top of the crankcase at cylinder numbers 1, 2, and 4. A 2-inch diameter piece of the crankcase rested on top of the engine. The oil drain plug was absent. The threads at the oil drain port showed no damage or evidence of safety wiring. The oil dip stick and oil filter showed heat damage. A film of oil was observed on the firewall. There was no evidence of oil in the engine.

An examination of the remaining airplane systems revealed no anomalies.

In his written statement, a mechanic at Crystal Airport, Minneapolis, Minnesota, said on September 12, 2001, he started an oil change on the airplane. The mechanic said that while the oil was draining, he noticed "missing and disintegrated nose gear vibration isolators". The mechanic said that he called the airplane's owner and informed him of the problem. The mechanic said, "Meanwhile, I abandoned all work, as I had no safety wire with me. And I didn't have a new crush washer for the drain plug. I then closed and locked the hanger. That's the last time I saw the aircraft."

A second mechanic stated that on September 18, 2001, he and his partner traveled to the Crystal Airport to repair the airplane's nose gear. He said that on his arrival, he noticed the engine was uncowled and was told that an oil change was being done by the owner's mechanic. The mechanic said that as he repaired the airplane's nose gear, his partner noticed that the oil filter safety wire was cut. The partner brought this to the attention of the owner. His partner was told that the filter was new and did not need replacing. The mechanic’s partner got some safety wire, safetied the filter, and added oil. The mechanic said, "I vividly remember checking the safety on the oil filter. I cannot remember the condition of the oil drain plug. We cowled the powerplant and conducted a leak check." The mechanic said that the pilot ran the engine for approximately one minute. It was then inspected for leaks. No leaks were found.

In the Pilot's Operating Handbook (POH) for the Cirrus Design SR20, under Landing Emergencies, Forced Landing, the text reads, "A suitable field should be chosen as early as possible so that maximum time will be available to plan and execute the forced landing. For forced landings on unprepared surfaces, use full flaps if possible." No reference to flap position is cited in the checklist steps. Figure 3-1 of the POH states the best glide speed (flaps up) for the airplane at 2,900 pounds (maximum certified weight) is 95 KIAS. Under Airspeed Indicator Markings in Section 2, Limitations, of the POH, it provides a marking entitled "White Arc" with an airspeed value of 56-100 KIAS and remarks, "Full Flap Operating Range. Lower limit is the most adverse stall speed in the landing confguration. Upper limit is the maximum speed permissible with flaps extended."

Parties to the investigation were the FAA and Cirrus Design Corporation.

NTSB Probable Cause

Improper servicing of the airplane by other maintenance personnel, inadequate inspection of the airplane by the other maintenance personnel prior to the airplane's flight, and the unsuitable terrain encountered during the forced landing. Factors relating to the accident were the oil exhaustion, the low ceiling providing the pilot little time to select a field once the airplane was beneath the clouds, the pilot not following proper emergency procedures requiring use of full flaps for the forced landing, and the corn crop.

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