NTSB Identification: CHI08FA027
14 CFR Part 91: General Aviation
Accident occurred Tuesday, October 23, 2007 in Browerville, MN
Probable Cause Approval Date: 12/28/2008
Aircraft: PIPER PA-44-180, registration: N327ND
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The accident flight was the third of a three-leg dual instructional night cross-country flight. The airplane was established in normal cruise flight at 4,500 feet mean sea level (msl) when the airplane abruptly departed controlled flight and impacted a bog. The bog was about 15 to 20 feet deep, with a thin layer of vegetation floating on the surface. The airplane came to rest inverted, and damage to the airframe was consistent with an inverted impact to the surface of the bog. Data recovered from the airplane's flight display system indicated that the airplane was in stable flight on a 320-degree magnetic heading, at 4,500 feet msl, and approximately 160 knots true airspeed prior to the accident, when it abruptly departed from controlled flight. The airplane rolled approximately 20 degrees left wing down, yawed to the left about 30 degrees, and simultaneously pitched nose-down about 40 degrees. It then reversed and immediately entered a descending, right roll for the duration of the flight. The airplane impacted the bog within 30 seconds of the upset. The post accident examination noted that the left half of the horizontal stabilator was bent upward approximately 90 degrees, inconsistent with the damage to the remainder of the airframe. This damage was consistent with the initial left yaw and nose down pitch recorded during the upset. In addition, a depression and tear were observed on the upper wing skin near the left wing tip. Microscopic examination and DNA testing of material on the inside surface of the wing skin was identified as remains of a Canada goose. The natural history of this species was consistent with the location, time, and date of the accident.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

An in-flight collision with at least one Canada goose, and the resulting damage to the left stabilator that caused the airplane to become uncontrollable. Contributing to the accident was the night lighting condition, which precluded any possibility of the flight crew seeing the bird(s) prior to impact.

Full narrative available

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