Intermittent Switches on JET Yaw Damper Computers

July 2017

Over the years, operators have sent Duncan Aviation's Avionics & Instrument Shop a number of inoperable JET Yaw Damper (YD) Computers for repair. They are quick to blame the PWR/TEST or Engage buttons as the culprits, but what they really should be looking at is the OFF switches.

The four OFF switches on these YD units are well known for becoming intermittent and stuck, causing the YD to not function.

If the PWR/TEST or ENG light won’t come on when pushed, the corresponding OFF switch has probably gone bad. Snapping this OFF switch a few times may help the unit to re-engage.

The FAA requires two functioning Yaw Damper (YD) Computers during all flights. If one suddenly quits, your aircraft is grounded. A potential temporary fix is to cycle through all of the OFF buttons by snapping them. This may cause them to re-engage so your flight can continue.

Once you get back home, send this unit to Duncan Aviation for repair. We have loaner units available while it is being fixed.

Years of JET Experience

At Duncan Aviation, we have been working on JET Components for more than 45 years. On average, we repair around 700 JET components each year with Current Manual data.

In addition to the Yaw Damper Computers, Duncan Aviation's Avionics & Instruments Shop has repair capabilities on the following units:

FC-110                                     Flight Control System

AD-101()                                  Air Data Computer

AV-500()                                  Accelerometer

AD-102()                                  Air Data Sensor

CA-260()/CA-261()                  Dual Fuel Monitoring System

IA-201B                                   Interface Adapter

CA-200()                                  Autopilot Computer

MT-101()                                 Mach Trim Computer

SP-101()                                   Spoileron Computer

YD-202()                                  Yaw Damper Computer

SA-500()/SA-501()                   Servo Actuator

SA-400()                                  Nose Wheel Steering Actuator

MW-701                                  Malfunction Warning

SA-200()                                  Servo Actuator

GL-100()/GL-200()                   G-Limiter

AC-200()                                  Controller

SA-460()                                  Servo Actuator

SA-461()                                  Servo Actuator

VG-206A                                  Vertical Gyro

VG-206B                                  Vertical Gyro

VG-206C                                  Vertical Gyro

VG-206E/L                               Vertical Gyro

VG-206F/L                               Vertical Gyro

VG-206G/L                              Vertical Gyro