Sunday, July 2, 2017

Air Tractor AT-502, N9185G, Air Assault LLC: Accident occurred July 07, 2014 in Carthage, Hancock County, Illinois




The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Springfield, Illinois

Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

Aviation Accident Data Summary - National Transportation Safety Board: https://app.ntsb.gov/pdf

http://registry.faa.gov/N9185G

NTSB Identification: CEN14LA349
14 CFR Part 137: Agricultural
Accident occurred Monday, July 07, 2014 in Carthage, IL
Probable Cause Approval Date: 09/14/2016
Aircraft: AIR TRACTOR INC AT-502, registration: N9185G
Injuries: 1 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The commercial pilot was taking off for an agricultural application flight. The pilot stated that, during the takeoff, the engine did not lose power but that the airplane was unable to gain sufficient speed to climb. After realizing the airplane was not accelerating or climbing as expected, the pilot dumped the chemical load in an attempt to gain altitude. The airplane became airborne and cleared a pond at the end of the airstrip, but it then contacted a dirt bank and nosed over on the far side of the pond. 

A postaccident examination of the airplane revealed that the engine torque gauge, which a mechanic had installed in the airplane about 3.5 months before the accident, was for a lower powered engine. The installation of the wrong gauge resulted in the redline on the gauge being lower than it should have been and likely resulted in the pilot not having an accurate torque indication and using a lower power setting than needed for the takeoff. 

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The airplane’s inability to climb out of ground effect, which resulted from the pilot using a lower power setting than needed for takeoff due to the mechanic’s installation of the wrong engine torque gauge. 

On July 7, 2014, about 1615 central daylight time, an Air Tractor AT-502 airplane, N9185G, collided with a pond at the end of a private airstrip during takeoff in Carthage, Illinois. The pilot received minor injuries, and the airplane was substantially damaged. The airplane was registered to and operated by Air Assault LLC as a 14 Code of Federal Regulations Part 137 aerial application flight. Visual meteorological conditions prevailed for the flight, which not operated on a flight plan. The local flight was originating at the time of the accident. 

The pilot reported the airplane was loaded with 364 gallons of chemical and both fuel tanks were ¾ full. He stated the wind was calm and the outside temperature was 88 degrees Fahrenheit. The takeoff was being made with 10 to 15 degrees of flaps extended. The pilot taxied to the end of the runway and applied the brakes while advancing the engine power. He released the brakes and the torque increased to 1,550 foot-pounds within 3 seconds. He noted the propeller rpm was above 2,200 and the first third of the takeoff was normal. The tail lifted off the airstrip about 2/3 the way down the runway and not at the half-way point as the pilot expected, nor did the aircraft accelerate as the pilot expected. The pilot stated that at this point he was committed to the takeoff so he dumped the load and attempted to fly the airplane. The airplane became airborne and cleared a pond, but contacted a bank on the far side of the pond, and the airplane flipped inverted. 

The pilot stated the engine did not lose power during the takeoff and given the conditions of the day, it should have flown. A postaccident examination of the aircraft by a Federal Aviation Administration inspector revealed that the Pratt & Whitney PT6-27 engine had been replaced with a higher powered -34 engine. On March 21, 2014, a new torque gauge was installed in the aircraft. The torque gauge installed was for the lower powered -27 engine which resulted in the redline on the gauge being lower than it should have been.

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