Incident Overview
A dual instructional flight was conducted in ambient temperatures ranging from 91 to 103 degrees Fahrenheit. The aircraft landed without incident. After clearing the runway, the pilot-in-command (PIC) did not follow the required procedure specified in the flight manual to turn off the anti-skid switch. Instead, the PIC used an outdated checklist card that contained the former procedure, leaving the anti-skid switch in the on position.
Sequence of Events
As the PIC maneuvered the aircraft to park, the anti-skid control unit malfunctioned. This malfunction caused the release of brake pressure. The PIC was able to regain control only after activating the emergency pneumatic brake system. By that time, the aircraft had collided with two other aircraft: a Cessna 500 and an Aero Commander 500S.
Background Factors
Two years prior to the incident, a service letter had been issued warning that the anti-skid control unit could malfunction at temperatures exceeding 100 degrees Fahrenheit. The operator of the aircraft had failed to comply with this service letter and had not submitted the unit for the required modification.
Recent Training
Within the month preceding the incident, the PIC and the company chief pilot had obtained type ratings in the aircraft from a designated pilot examiner.