NTSB Identification: CHI05FA016.
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Accident occurred Tuesday, October 26, 2004 in Wautoma, WI
Probable Cause Approval Date: 07/07/2005
Aircraft: Cessna P210N, registration: N5485W
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 airplane was destroyed during an in-flight break-up and subsequent impact with terrain. The pilot advised the controller that the airplane was losing its gyros and that he needed to descend. The pilot then reported that the gyros appeared to be working. The controller advised the pilot that the airplane was on a southwest heading and that the pilot could fly whatever altitude he was able to maintain. The controller was looking for an airport with visual meteorological conditions present and asked the pilot if the airplane was in the clouds. The pilot reported affirmative. The pilot's last transmission was that it was going into a spin. Radar contact was lost about that time. In a Sheriff's report, two witnesses indicated that they heard thunder or jets flying. The report showed that they heard a "high winding noise from [the] plane engine." The noise was directly above their position and they heard a loud bang. They reported seeing a plane at about 1,500 to 2,000 feet above ground level. The airplane was observed spinning straight down without its wings. The witnesses indicated that they observed something hanging from its tail section. A Meteorological Factual Report was compiled and the flight's plotted radar track showed that the airplane was in layered clouds and that there was visual flight rules weather conditions below the clouds. Recorded groundspeed varied between 130 to 160 knots. Winds aloft were headwind and quartering winds. The airplane's information manual's limitations section stated, in part, "Maneuvering Speed:4000 pounds-130 Knots Indicated Air Speed (KIAS), 3350 pounds-119 KIAS, 2700 pounds-106 KIAS Remarks: Do not make full or abrupt control movements above this speed." A flapper valve in the vacuum manifold exhibited deterioration and a crack. General observation of the manifold revealed that it had been disassembled and reassembled with non-manufacturer specified rivets. No further airframe of engine preimpact anomalies were detected with the recovered wreckage. Examination of instrument gyro rotors revealed rotational scoring.
Post-accident toxicology evaluation of specimens from the pilot was consistent with the intermittent use of fluoxetine (a prescription antidepressant often known by the trade name Prozac). The pilot did not indicate any mental conditions or the use of any psychiatric medications on applications for airman medical certificate.

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

The pilot not maintaining airplane control during cruise flight in instrument meteorological conditions after reporting a loss of gyros leading to his exceeding the design load limits of the wings. Factors were the clouds, the deteriorated vacuum manifold flapper valve, and the non-factory modification of that manifold by an unknown party.

Full narrative available

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