NTSB Identification: DEN06GA128.
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Accident occurred Thursday, September 14, 2006 in Fort Meade, FL
Probable Cause Approval Date: 05/29/2007
Aircraft: Piper PA-23-250, registration: N5941Y
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 public aircraft accident report.

The airplane was being used for mosquito control and was carrying Scourge insecticide (Bayer), a mixture of resmethrin, piperonyl butoxide, and naphtalene. A witness said the airplane passed overhead at low altitude. He heard the engines "throttle back, then rev up and sputter." He said he could tell the right engine was sputtering because "the propeller was turning slowly." He saw the airplane pitch up, roll to the right, and descend into the ground. The airplane immediately caught fire. The on-scene investigation revealed one blade on the left propeller assembly was curled aft and the other blade was curled forward. One blade on the right propeller assembly was curled aft and the other blade was straight. Both engines later were disassembled and inspected. Crankshaft rotation produced camshaft, valve, and accessory drive continuity on both engines. No anomalies were noted with either engine's lubrication, induction, fuel injector, exhaust, and ignition systems. Examination of the spark plugs and cylinders revealed normal burn patterns and color. All cylinders produced compression except the right engine's number 6 cylinder. According to the manufacturer, its intake and exhaust valve springs had lost tension as a result of having been exposed to the fire. Both the left and right propeller governor controls were in the high rpm position.

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

A loss of power in the right engine while manuevering for reasons undetermined, and failure to maintain aircraft control which resulted in an inadvertent stall. Contributing factors were the airspeed below Vmc, and an altitude too low to afford a safe recovery..

Full narrative available

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