ELKO, NV, USA
N99G
HAYES DICKEY E-RACER
IN CRUISE, THE PROPELLER SEPARATED FROM THE AIRCRAFT. THE PILOT ATTEMPTED TO LAND ON A DIRT ROAD, BUT HAD INSUFFICIENT ALTITUDE AND COLLIDED WITH HIGH VEGETATION AND ROUGH TERRAIN. POST ACCIDENT INSPECTION REVEALED THAT THE PROPELLER SEPARATED FROM THE PROPELLER EXTENSION ASSEMBLY AT THE PROPELLER FLANGE. THE PROPELLER AND THE ATTACHED FLANGE WERE NOT RECOVERED. THE PROPELLER EXTENSION ASSEMBLY IS A BARREL-SHAPED MACHINED ALUMINUM PART WITH FLANGES ON EACH END OF THE BARREL, ONE FOR CONNECTION TO THE ENGINE CRANKSHAFT AND ONE FOR CONNECTION TO THE PROPELLER. THE PROPELLER FLANGE FRACTURED AWAY FROM THE BARREL AT A RADIUS FORMED BETWEEN THE BARREL AND THE FLANGE. BEACH MARKINGS WERE OBSERVED EMANATING FROM A POINT ON THE SURFACE AT THE RADIUS WITH BEACH MARKS ABOUT 1/2 ACROSS THE BARREL WALL. A REPORT SUBMITTED BY THE AIRCRAFT OWNER NOTED THAT THE RADIUS BETWEEN THE BARREL AND THE FLANGE WAS MEASURED AT BETWEEN 1/8 AND 3/32 OF AN INCH, WITH FLAT SPOTS AND SCORING NOTED. THE PROPELLER EXTENSION ASSEMBLY WAS NOT MANUFACTURED IN ACCORDANCE WITH A PARTS MANUFACTURING OR TYPE CERTIFICATE APPROVAL.
On July 3, 1994, at 1216 Pacific daylight time, an experimental homebuilt Hays Dickey E-Racer, N99G, collided with ground obstructions and collapsed the landing gear during a forced landing near Elko, Nevada. The forced landing was precipitated by an in-flight loss of the propeller during cruise. The aircraft was owned and operated by the pilot and was on a cross- country personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed for the operation. The aircraft incurred substantial damage. Neither the certificated commercial pilot nor the one passenger were injured. The flight originated at Jackpot, Nevada, on the day of the accident at 1145 hours as a flight to Elko. The pilot reported that he had retorqued the propeller bolts about 5 hours prior to the accident. The pilot stated that while in cruise the propeller separated from the aircraft. The pilot attempted to land on a dirt road, but had insufficient altitude. The pilot landed in the desert and collided with high vegetation and rough terrain. Postaccident inspection of the aircraft revealed that the propeller separated from the propeller extension assembly at the propeller flange. The propeller and the attached flange were not recovered. The propeller extension assembly is a barrel-shaped, machined aluminum part overall measuring 15.5 cm in length by 8.8 cm in diameter. Flanges measuring 15.2 cm in diameter by 2.2 cm in thickness are on each end of the barrel, one for connection to the engine crankshaft and one for connection to the propeller. A 4.4 cm diameter bore is machined longitudinally in the barrel. The propeller flange fractured away from the barrel at a radius formed between the barrel and the flange. The fracture plane was observed to occur at a point about 1/3 to 1/2 of the radius. Beech markings were observed emanating from a point on the surface at the aforementioned radii. The beech marks proceed 17 mm across the 22 mm thick barrel wall, then change to a flat plane fracture with a granular characteristic. Directly opposite the beech marks, a pie-shaped wedge was noted to be fractured into the barrel comprising an 88-degree arc around the circumference of the barrel and tapering longitudinally to a near point 7.9 cm from the fracture plane. A report submitted by the aircraft owner noted that the radius between the barrel and the flange was measured at between 1/8 and 3/32 of an inch, with flat spots and scoring noted. The propeller extension assembly was not manufactured in accordance with a Parts Manufacturing or Type Certificate Approval.
a fatigue fracture and separation of the propeller flange from an improperly machined propeller extension assembly. Inadequate design, substantiation, and approval of the part design was a factor in the accident.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
