Ensure adequate spacing behind the unit for the rear electrical mating connector and pneumatic hose fittings [1.12].
Air-driven internal gyro requiring a vacuum/pressure source delivering 4.5 to 5.2 inches of mercury (in. Hg) .
Note: This piece is a technical excerpt for documentation purposes. Always consult the complete OEM manual and current aircraft maintenance data before performing installation.
Before beginning installation, ensure the unit matches your aircraft's electrical and physical configuration.
Turn on the 400 Hz inverter. The Gyro Warning Flag must retract from view within 3 minutes as the gyro reaches operational RPM. ki 256 installation manual
Use flexible, instrument-grade rubber hoses secured with approved hose clamps.
I can provide specific wiring schematics or troubleshooting steps for your exact configuration. Share public link
Forced air cooling via a dedicated avionics fan duct is highly recommended.
| Pin | Function | Wire Gauge | |-----|----------|-------------| | 1 | +14V/28V DC | 22 AWG | | 2 | Ground | 22 AWG | | 3 | Gyro motor power (from KA 51B pin 6) | 22 AWG | | 4 | Synchro rotor R1 | Shielded 24 AWG | | 5 | Synchro rotor R2 | Shielded 24 AWG | | 6 | Synchro rotor R3 | Shielded 24 AWG | | 7 | Flag drive (to KI 525A) | 24 AWG | | 8 | Panel light hot (5V AC/DC or 14V/28V per dimmer) | 22 AWG | | 9 | Panel light ground | 22 AWG | | 10 | Not used | – | | 11 | Not used | – | | 12 | Shield drain (case ground) | – | Ensure adequate spacing behind the unit for the
This guide provides a technical overview of the procedures, wiring, and maintenance standards. Disclaimer
The KI 256 is a TSO-certified instrument. Installation must be performed by qualified personnel in accordance with the aircraft manufacturer’s maintenance manual and applicable airworthiness regulations (e.g., FAR 43). A logbook entry and updated weight & balance may be required.
: Many installations require this modification to reduce loading effects on pitch and roll outputs, particularly when paired with the KC-192 autopilot computer. This involves replacing the internal PC board. Handling Precautions
Leave a comment below or consult a Honeywell-authorized repair station. Note: This piece is a technical excerpt for
Mount the aircraft (or use a gyro tilt stand) to a level flight attitude.
Mount the unit using non-magnetic brass screws to avoid affecting nearby magnetic compasses. 2. Wiring Harness Construction
After alignment, perform a “gyro caging” via the KCS 55 controller (if equipped) before first power-up. The manual’s Section 3.2 covers the 2-minute warm-up period.