# SDR 2026FA0000254

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: April 6, 2026
- Submitted: April 6, 2026
- Operation: General aviation
- Aircraft: [N787LP](https://openairdocs.org/aircraft/N787LP), registered now
- Make and model: Bombdr BD1001A10
- Aircraft serial: 20835
- Aircraft time: 972 hours, 616 cycles
- System (JASC): [2210 · Autopilot System](https://openairdocs.org/jasc/2210)
- Part: Flight Dir
- Part number: 8221574001
- Part serial: ALL
- Condition: Defective
- Location: Cockpit
- Part time: 972 hours, 616 cycles
- Stage of operation: DE
- How discovered: O
- Nature of condition: F
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2026FA0000254

## Discrepancy

FLIGHT GUIDANCE PANEL ON GOING SAFETY OF FLIGHT ISSUE CONCERNING INADEQUATE DESIGN/DURABILITY OF CERTAIN COMPONENTS. FLIGHT GUIDANCE PANEL(FGP) EQUIPPED AIRCRAFT.OUR AIRCRAFT.  OUR ORIGINAL FGP, ELECTRONIC ROTARY HDG,/SPEED/ALT. PRESELECT SWITCHES STARTED HAVING ISSUES JULY 2024 AS AN OEM UNIT, IT WAS REPLACED WITH A REPAIRED UNIT FROM THE MANUFACTURER SEPT. 2024, THEN AGAIN IN SEPT. 2025 WITH REPAIRED UNIT FROM THE MANUFACTURER DUE TO THE SAME CONDITION.
THE PROBLEM WE EXPERIENCED WAS SHIFT LOWER IN ALTITUDE PRESELECTED ALTITUDE FROM A SET FL370 TO FL360.  SECOND UNIT PRESELECT PRIOR TO DEPARTURE, AFTER RECEIVING IFR CLEARANCE TO 2000', WHILE WAITING FOR THE PASSENGERS WE WERE SEATED IN THE CABIN AND HEARD THE ALTITUDE ALERT WARNING CHIME.  UPON CHECKING IT OUT WE FOUND THE PRESELECT HAD SHIFTED TO 1000' BY ITSELF SETTING OFF THE "ONE TO GO" DECENT WARNING.  THE NEWER CHALLENGER 3500 ARE EQUIPPED WITH AUTO-THROTTLES WHICH ARE CONTROLLED BY THE SPEED CONTROL KNOB WHICH IS OF THE SAME DESIGN.    CUSTOMER REPLACED FGP WITHIN LAST YEAR AND IS HAVING ISSUES WITH HIS HDG AND ALT SELECT KNOB AGAIN CAUSING ISSUES IN FLIGHT CONTROLLING THE AP. IS THERE ANY RELIABILITY IMPROVEMENT FOR THESE PANELS?  IS IS A KNOWN ISSUE THAT COLLINS HAS BEEN WORKING WITH ROTARY SWITCH SUPPLIER. IN ADDITION, THIS IS A TOPIC ON BOMBARDIER EXECUTIVE MEETING. IMPLEMENTED PREVENTATIVE MAINTENANCE? TO REPLACE ALL 3 ROTARY SWITCHES? AT EACH REPAIR TO ELIMINATE NFF’S?.

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