Five Points, CA, USA
N8598H
GRUMMAN ACFT ENG COR-SCHWEIZER G 164A
The pilot reported that, shortly after takeoff for the aerial application flight, the engine lost power. The pilot subsequently initiated a forced landing to a field. The airplane impacted the ground and flipped over. The engine manufacturer's table of limits specified that the minimum side clearance/tolerance between a starter shaft circumference and a starter shaft bushing should be 0.002 inch. However, during postaccident examination, there was no measurable clearance between the starter shaft circumference and the starter shaft bushing, which impeded oil flow to the impeller shaft and bearings and resulted in the failure of the supercharger-blower due to a lack of lubrication. The engine had accumulated 2.0 hours since its last major overhaul, and it is likely that maintenance personnel improperly reassembled the engine during the overhaul.
On June 21, 2015, about 0600 Pacific daylight time, a Grumman Aircraft ENG COR-Schweizer G 164A, N8598H, sustained substantial damage following a loss of engine power and subsequent emergency landing near Fresno, California. The airplane was registered to, and operated by, Kenny's Crop Dusting, Inc., under the provisions of 14 Code of Federal Regulations (CFR) Part 137 as an aerial application flight. The pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed for the flight, which operated without a flight plan. The local flight was departing a private airstrip at the time of the accident. The pilot reported that shortly after takeoff, about 50 feet above ground level, the engine lost power. The pilot initiated a forced landing to a field. The airplane impacted the ground and came to rest inverted. On August 5, 2015, the engine was examined at the facilities of Tulsa Aircraft Engines, Tulsa, Oklahoma. A complete report on the examination is part of the public docket for this accident. The starter drive gear was locked, and unable to rotate by hand inside the blower assembly. The starter drive gear exhibited heat bluing. The starter shaft circumference measured the same dimensions as the starter shaft bushing; there was zero (0) side clearance/tolerance. To lubricate the shaft and the bearings, oil was directed from a hole inside the starter shaft bushing. The Pratt & Whitney R-1340 engine table of limits indicated that the minimum required side clearance/tolerance between the starter shaft and the starter shaft bushing was 0.002 inches. The examination revealed that the engine's blower had failed due to lack of lubrication to the impeller shaft and bearings. At the time of the accident, the engine had accumulated 2.0 hours since its last major overhaul. A review of maintenance records showed that the last major overhaul was dated February 21, 2013, at a total aircraft time of 3,952.76 hours. The engine was installed on the airplane on June 4, 2015.
Maintenance personnel’s improper reassembly of the engine during overhaul, which led to the failure of the supercharger-blower due to a lack of lubrication and the subsequent total loss of engine power during takeoff.
Source: NTSB Aviation Accident Database
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