NTSB Identification: CHI04FA198.
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Accident occurred Wednesday, July 28, 2004 in Fox Lake, IL
Probable Cause Approval Date: 12/20/2005
Aircraft: Mooney M20J, registration: N91381
Injuries: 2 Fatal,1 Serious.
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 when it impacted a road following an uncontrolled descent. Examination of the airplane revealed no anomalies existed prior to impact. The pilot seated in the left seat had recently purchased the airplane. The pilot seated in the right seat was a certified flight instructor. According to the CFI's logbook, he had 2,401.4 hours total flight experience and 62.6 hours experience as a flight instructor. Radar track data showed the aircraft departed Palwaukee Airport, Wheeling, Illinois, and proceeded toward Fox Lake, Illinois. The last recorded radar return coincided with the time and location of the accident site. The radar data showed that during the 3 minutes prior to the last return, the airplane's groundspeed slowed from 158 knots to 70 knots while the altitude returns remained between 2,300 and 2,500 feet. The last two radar returns show the airplane descending through 2,200 feet and 1,700 feet pressure altitudes, respectively. The calculated ground speed during these last two radar returns was 63 knots and 42 knots, respectively. The Pilot's Operating Handbook for the airplane lists stall speeds with 0-degree bank angle between 48.5 knots and 59 knots calibrated airspeed (CAS) depending on weight and configuration. The gear-up, flaps-up stall speed at 2,300 pounds and 0-degree bank angle was listed at 54 knots CAS. The gear-down, flaps 33-degree stall speed for the same weight and bank angle was listed as 48.5 knots CAS.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The flight crew's failure to maintain airspeed which led to an inadvertent stall/spin. An additional cause was the flight instructor's unsuccessful remedial action during the course of the accident sequence. The slow flight performed was a factor. Full narrative available
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