Ki 256 Installation Manual Link

The BendixKing KI 256 Go to product viewer dialog for this item.

is a critical flight command indicator that integrates a self-contained vertical gyro to provide pilots with essential pitch and roll attitude data. Because it serves as the primary attitude source for various BendixKing Flight Control Systems—including the KFC-150, KFC-200, and KFC-250—following its installation and maintenance protocols is vital for flight safety and autopilot reliability. Core Technical Overview

is designed to be more than a simple display; it is a complex electro-mechanical unit that supplies real-time data to the aircraft's flight computer.

Gyro Functionality: It contains a vertical gyro that drives the horizon mask and provides attitude signals to the autopilot system.

Command Bars: A single-cue command bar displays computed flight director commands, helping the pilot follow the autopilot's intended path. ki 256 installation manual

Panel Compatibility: Units are specifically calibrated for either zero-degree or eight-degree instrument panels to ensure accurate visual alignment during flight. Installation and Modification Protocol Proper handling of the

is mandatory to prevent internal damage and ensure system precision.

Static Protection: All disassembly and assembly must occur at a static-safe workstation. Components removed from the unit should be stored in static-safe bags to prevent electrostatic discharge damage.

Alignment Procedures: For systems like the KFC 200, a full system alignment may be required during installation. This involves using specialized tools like a regulated 4.5 in. Hg. air source and connecting the gyro to the airplane harness via an extender cable to verify operation. The BendixKing KI 256 Go to product viewer

Component Replacement: When updating internal parts, such as the Command Bar Board, technicians must verify that wire connection points match the original layout, though specific pin locations (like E114) may shift between board revisions. Verification and Compliance

After any installation or internal modification, the unit must undergo rigorous validation.

Functional Testing: Technicians must perform a complete functional test as outlined in Section VI of the KI 256 Maintenance Manual to ensure the indicator responds correctly to pitch and roll inputs.

Identification: Completed modifications must be documented by marking the Unit Serial Tag. If space is unavailable, a new Mod Tag must be applied nearby to maintain a clear service history. Part 6: Common Installation Errors (From Actual Field

Operational Checks: During initial power-up, a distinct "whine" from the gyro's power supply should be audible, indicating the internal motor is spinning up to operational speed.

⚠️ Note: Always consult the most current version of the official BendixKing Downloads & Manuals or professional aviation documentation sites like Scribd before performing any work.

If you are looking for specific details, I can help you find: The pinout diagram for the rear connector. Specific troubleshooting steps for a "tumbled" gyro. Information on vacuum vs. electric versions. KI 256 Flight Command Indicator

Part 6: Common Installation Errors (From Actual Field Reports)

Based on service bulletins and the ki 256 installation manual supplementary sheets, these are the top 5 mistakes:

1. Reversing Roll and Pitch Wires: This causes the HSI to show pitch when the aircraft rolls. Symptom: in a left turn, the attitude indicator shows nose up.
2. Ignoring the 400Hz Frequency Tolerance: The gyro spin motor requires 115V ±5V at 400Hz ±10Hz. Standard 60Hz inverter will destroy the KI 256 in minutes. Use a dedicated 400Hz alternator or solid-state converter (e.g., PS Engineering).
3. Using Unshielded Lighting Wires: The 28V dimmer circuit (pin 14) must be shielded. Unshielded wires inject flicker noise into the syncro outputs.
4. Forgetting the “Gyro Run” Flag: If pin 11 (Flag Out) is not connected to the HSI’s warning input, the pilot will have no failure indication when the gyro topples.
5. Mounting on an Unstable Panel: Thin aluminum panels flex during turbulence. The manual specifies a minimum 0.063” thick mounting plate.

4. Section 4: Preflight and Operational Check

• 4.1 Uncage Check: Ensure the attitude gyroscope is uncaged (pulling the knob out) after engine start and vacuum is established.
• 4.2 Erection Time: The gyro should erect to the correct vertical position within approximately 2 to 3 minutes.
• 4.3 VSI Calibration: During engine run-up, the VSI needle should indicate zero on the ground. If it reads non-zero, a zero-adjustment screw (typically on the lower left or right of the bezel) allows for mechanical adjustment.
  • Adjustment Text: "Use a small screwdriver to adjust the zero-set screw until the VSI needle aligns with the zero mark. Do not force the adjustment beyond its stops."

Network / Communication (if applicable)

• Connect Ethernet to the RJ45 port; default IP: 192.168.1.100 (change per network).
• For serial: use RS-485 A/B to the corresponding terminals; set termination jumper if at line end.

7. Common Installation Errors & Troubleshooting

Even experienced techs fall into these traps. The KI 256 installation manual lists them, but here’s the real-world summary:

| Symptom | Likely Cause | Solution | |---------|--------------|----------| | No attitude display, but power on | Missing 400Hz AC reference from remote gyro | Check continuity on pins 4 & 6 | | Erratic flight director bars | Shield not grounded at source | Terminate shield at remote gyro case | | Slow gyro spin-up | Low voltage drop across circuit breaker | Measure voltage at pin 1 under load (min 11.5V for 14V system) | | Flag “GYRO” visible after warm-up | Remote gyro failure or disconnected | Verify KG 258 or KG 102 power & wiring | | Roll indicates opposite direction | Synchro stator leads swapped | Swap any two of pins 12/13/14 |