Accident Overview
On February 21, 2018, about 1015 Pacific standard time, an experimental, amateur-built G-2 airplane (registration N90SR) was involved in an accident near Elko, Nevada. The pilot sustained serious injuries. The airplane was operating under 14 Code of Federal Regulations Part 91 as a personal flight.
Events Leading to the Accident
According to the pilot, upon landing, the airplane's left brake was inoperative. He performed a go-around and set up for a single-brake landing. The subsequent landing was uneventful, but the left brake remained inoperative. With about 1,500 ft of runway remaining, the pilot chose to veer to the right off the runway surface to avoid running off the end. Subsequently, the airplane struck a drainage ditch berm.
Brake System Description
The wheel brake system was hydraulically driven, with each brake operating independently from the front or rear cockpit and from the right or left side. A hydraulic fluid reservoir was located in the front cockpit, with a fluid quantity window.
Examination Findings
Examination revealed substantial damage to the fuselage and separation of the nose and left main landing gear struts. When the left brake pedal was depressed, hydraulic fluid expelled from a severed portion of lines under the left wing. The reservoir contained a normal quantity of fluid, between the maximum and minimum levels. No leaks were noted in the cockpit area or on the left wing interior or exterior. Hydraulic fluid was observed on the left main landing wheel area; it was clear and red. Three separated brake pucks were found in the left wheel area.
Examination of the left brake assembly showed that the separated ends of the hydraulic lines were still secured and safety wired. Two brake rotors were loose, and the No. 2 brake cylinder worn pin indicator was recessed. The other three brake cylinders’ wear pins were in the normal position.
Findings on the No. 2 Brake Cylinder
Disassembly of the No. 2 brake cylinder revealed it was not properly installed, allowing the brake pucks to move. This movement resulted in three pucks separating from the brake assembly. The separation of the brake pucks could allow the No. 2 cylinder's piston to move to its full-scale inward position. The full-scale deflection of the piston could result in a hydraulic leak and cause insufficient hydraulic pressure to the other brake cylinders, rendering the brake inoperative.
Accident Site Details
According to the airport manager’s report and a review of photographs, during the landing, the airplane exited the runway with about 1,675 ft of runway remaining.