Learjet Fall 1997

• Simulate Your Learjet Steering System
• Accessory Expansion Underway
• Autopilot Heading Problems In Your 30 Series? Don't Overlook the SIU
• Engine Shop Begins First Carbon Seal Inspection
• Cockpit Floor Warmer STC

Simulate Your Learjet Steering System

Duncan’s new dynamic nose wheel steering closed loop test panel can simulate the Learjet steering system. Designed and built by Duncan, this new piece of test equipment utilizes all actual aircraft followups to place the servo and nose wheel steering computer together in one interactive circuit. This test panel can simulate pilot commands, actual nose strut follow-up feedback, load the servo (to simulate aircraft weight), simulate aircraft speed, measure nose turning degrees and test circuitry in the steering computer that the OEM’s test equipment didn’t check.

For more information about this exciting new test panel, please contact Chris Gress at 1.800.228.4277.

Accessory Expansion Underway

Duncan’s Accessory Shop is being expanded. This added space will allow us to more efficiently process workloads, speed up turntimes and allow for additional test equipment and exchange unit storage. Our time & material exchange program includes advantages like:

• Exchange price = Overhaul your core unit + a small exchange fee
• Only one removal and installation
• A minimum of downtime

For more information about our accessory capabilities, please contact Chris Gress at 1800.2284277.

Autopilot Heading Problems In Your 30 Series? Don't Overlook the SIU

Because so many LRN Systems are being retrofitted, there is a potential for failures that cause symptoms apparently unrelated to the FMS. Installations incorporating a “steering interface unit” (SIU) could exhibit these problems.

The FC-200 autopilot was not designed to receive roll steer information; earlier FMS installations provided the autopilot with information comparable to VOR signals.

Since roll steer information provides better system operations, an SIU was developed to allow the FC-200 autopilot to accept this information. The SIU does this by interrupting the normal heading error from the heading BUG on the HSI and substituting roll steer information from the FMS.

If you select NAV on the autopilot mode selector to track the FMS, the SIU intercepts the signal and tells the autopilot it is in heading, but the mode selector indicates NAV capture.

So, if your autopilot is INOP in heading and you’ve changed the autopilot computer and the HSI and it’s still INOP; check that SIU!

To find out more about your SIU, call Rick Whitesell at Duncan Avionics, 1.800.228.4277 or our Tech Reps at 800.LOANERS.

Engine Shop Begins First Carbon Seal Inspection

The first industry inspection of the new style #l and #3 carbon seals and runners was recently performed at Duncan. These seals were installed 1400 hours ago and made it through the entire MPI interval without any problems. The carbon seals appeared to be in excellent condition, showing little wear or carbon buildup. The seal runners were in the same excellent condition. They showed even wear patterns and no signs of seal skipping. The #l carbon seal and rotor were reinstalled. Although the #3 carbon seal was also in excellent condition, it was removed and sent to Phoenix for further testing. The seal runner was reinstalled with a new #3 carbon seal.

For more information about SB 72-3613, please contact Cecil Sloan or Jon Dodson at 1.800.228.4277.

Cockpit Floor Warmer STC

Duncan has received an STC for installation of cockpit floor warmers in 20/30 series aircraft. The company also received PMA, allowing Duncan to create kits that operators may purchase to install the warmers.

The system is easy to operate, provides individual controls for pilot and co-pilot floorboards and includes three different temperature settings.

For more information, please contact Skip Laney at 1.800.228.4277.

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