Felton, DE, USA
N5495
Grumman G-164A
While returning to a private airstrip, the pilot heard a loud explosion from the engine. The engine lost all power, and the pilot performed a forced landing to a soybean field. During the landing, the right wing contacted the ground and the airplane came to rest inverted. The airplane was equipped with a Honeywell (Garrett) TPE331-43A turboprop engine. Examination of the engine revealed that the second stage turbine rotor was fractured, separated, and lodged in the back of the engine. The second stage turbine stator seal plate assembly exhibited warpage. The evidence was consistent with the warped second stage turbine stator seal plate contacting the second stage turbine rotor, causing the rotor to separate. Airworthiness directive (AD) 86-08-06 R1 pertained to the accident engine, and required an x-ray inspection of the second stage turbine stator seal plate assembly. The purpose of the AD was to detect and repair engines with second stage turbine stator seal plate assemblies that exhibited warpage. The last annual inspection of the airplane was performed about 4 months prior to the accident. According to the aircraft logbooks, the airframe and powerplant mechanic with an inspection authorization (IA) noted the AD as not applicable due to engine model number. However, the subject engine model number did require completion of the AD.
On August 1, 2005, about 0940 eastern daylight time, a Grumman G-164A, N5495, was substantially damaged during a forced landing, following a total loss of engine power while maneuvering near Felton, Delaware. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local aerial application flight conducted under 14 CFR Part 137. The pilot stated that he was returning to a private airstrip after a 25-minute aerial application flight. The airplane was about 500 feet agl, when the pilot heard a loud explosion from the engine. The pilot immediately began looking for a suitable field to perform an emergency landing. He then observed a soybean field, and initiated a right turn in an attempt to glide to the field. The airplane was descending rapidly, and before the pilot could level the wings, the right wing contacted the ground. The airplane subsequently bounced hard on the main gear and came to rest inverted. The airplane was equipped with a Honeywell (Garrett) TPE331-43A turboprop engine. Initial examination of the engine by a Federal Aviation Administration (FAA) inspector revealed that the second stage turbine rotor had separated. The engine was subsequently disassembled and inspected at the manufacturer's facility, under the supervision of an FAA inspector. The inspector noted that the second stage turbine rotor was fractured, separated, and lodged in the back of the engine. The second stage turbine stator seal plate assembly exhibited warpage. In addition, the forward face of the second stage turbine rotor exhibited a cut groove, consistent with contact between the second stage turbine stator seal plate and the second stage turbine rotor. The FAA inspector stated that airworthiness directive (AD) 86-08-06 R1 pertained to the accident engine, and required an x-ray inspection of the second stage turbine stator seal plate assembly. The purpose of the AD was to detect and repair engines with second stage turbine stator seal plate assemblies that exhibited warpage. The last annual inspection of the airplane was performed in April 2005, by an airframe and powerplant mechanic with an inspection authorization (IA). According to the aircraft logbooks, the IA noted the AD as "N/A by model #." However, the subject engine model number did require completion of the AD.
The mechanic's inadequate annual inspection, and failure to comply with an airworthiness directive, which resulted in a total failure of the second stage turbine rotor.
Source: NTSB Aviation Accident Database
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