What happened
The flight originated at Boca Raton Airport in Florida around 1130 EST on April 17, 1985. N711WJ, a De Havilland DH-125 registered to Rynes Aviation, Inc., was operating under an IFR flight plan with Ronald F. Rynes as the pilot. While preparing for descent into Chicago with the intention of landing at Meigs Field, the crew detected a total loss of hydraulic system pressure in the normal system.
Due to the severity of the malfunction and the need for enhanced emergency response capabilities, the decision was made to divert to Chicago O'Hare International Airport. Upon arrival, visual meteorological conditions prevailed. However, the loss of hydraulic pressure rendered the aircraft's brakes inoperative. As a result, N711WJ was unable to stop on the runway and collided with a fence and a movable passenger loading stairs.
Despite the collision, there was no fire, and the occupants were not injured. The aircraft sustained minor damage. The accident occurred at 1319 CST on April 17, 1985.
The investigation
The investigation focused on the mechanical failure that led to the loss of braking capability. Examination revealed a total loss of hydraulic pressure within the normal system of the DH-125. This systemic failure directly resulted in the inoperability of the wheel brakes during the landing roll at O'Hare International Airport.
Findings
The primary factor contributing to the incident was the total loss of hydraulic pressure which rendered the brakes inoperative. The crew's decision to divert to a facility with greater crash fire rescue capability was appropriate given the circumstances, but the mechanical failure ultimately led to the runway excursion and subsequent collision with ground infrastructure.