Fix elevator trim not working in FS2004 by checking Num Lock, bindings, joystick axes, autopilot conflicts and aircraft-specific faults.
Elevator trim in FS2004 usually stops responding because Num Lock is set incorrectly, the trim commands have lost their assignments, a joystick trim axis is overriding keyboard inputs, or the autopilot is controlling pitch. Test the default keys in a stock aircraft, then isolate controller and aircraft-specific conflicts.
Which keys control elevator trim in FS2004?
With the default FS2004 keyboard layout, the elevator-trim commands use the numeric keypad and normally require Num Lock to be off.
| Command | Default input | Result |
|---|---|---|
| Elevator trim up | Numeric keypad 1 | Nose-up trim |
| Elevator trim down | Numeric keypad 7 | Nose-down trim |
The number keys across the top of the keyboard are not substitutes for the keypad keys. On a laptop without a dedicated numeric keypad, use its Fn keypad combination or assign different keys. Our guide to the default FS2004 control layout covers the other keyboard commands, while the printable FS2004 command reference is useful for checking keypad shortcuts.
How do I fix FS2004 elevator trim controls?
- Establish a clean test. Load the stock Cessna 172 in flight, switch off the autopilot and altitude hold, leave slew mode, unpause the simulator and click the main flight view so that no menu or dialogue has keyboard focus.
- Test the default keypad commands. Turn Num Lock off and press numeric keypad 1 or 7 several times while watching the cockpit trim wheel or indicator. One trim increment can be too subtle to detect, but avoid holding the key until the trim runs to its limit.
- Check the command assignments. Open FS2004's Controls/Assignments screen and find the elevator-trim up and down commands. Restore or replace any missing bindings. Laptop users can assign ordinary keys that are not already used elsewhere; our instructions for reassigning FS2004 keyboard and joystick controls cover this process.
- Remove unwanted trim-axis assignments. Check every connected yoke, joystick, throttle quadrant, gamepad and trim wheel. Clear the elevator trim axis from devices that should not control it. If you use a physical trim wheel, make it the sole trim-axis source; if you use keys or buttons, an absolute trim axis is usually best left unassigned.
- Disconnect extra controllers. Close FS2004, temporarily disconnect non-essential devices, restart the simulator and retest. If trim begins working, reconnect devices one at a time until the conflicting assignment appears.
- Regenerate the control configuration only as a last resort. If several unrelated controls are corrupt, close FS2004, back up and rename
fs9.cfgin the per-user application-data folder, then restart. FS2004 will create a fresh file, but graphics, sound and controller preferences will also need resetting.
Why does elevator trim move and then jump back?
A physical trim axis is the usual cause when keyboard or button trim moves briefly and immediately returns. The key changes the trim setting, then the next signal from the absolute hardware axis forces it back to the wheel's physical position.
Either use the hardware wheel and stop using incremental trim buttons, or delete that axis assignment and retain the buttons. Duplicate assignments in controller software can produce the same symptom.
The autopilot is the other common cause. Pitch or altitude-hold logic may move or counter the trim, particularly in aircraft with custom autopilot gauges. Disconnect the entire autopilot for the test rather than switching off only one mode.
Why does trim work in default aircraft but not an add-on?
If elevator trim works in the stock Cessna but not in one add-on aircraft, the FS2004 control system is functioning and the fault is aircraft-specific. Custom panels may implement electric trim through gauges, require aircraft power, intercept standard commands or depend on files that were not installed correctly.
Check the aircraft's included instructions and test both its panel control and the standard FS2004 command. Reinstalling a clean copy is safer than randomly changing trim-effectiveness values in aircraft.cfg, which can alter the flight model without repairing a missing gauge or control script.
Is trim broken if the aircraft will not hold altitude?
No. Elevator trim balances pitch for a particular speed and power setting; it does not hold an assigned altitude like an autopilot. Changes in airspeed, power, flap position or centre of gravity will require retrimming.
With a spring-centred desktop joystick, you cannot feel the reduction in control force that a real pilot would feel. Judge FS2004 trim by stabilising the aircraft, releasing pitch input and checking whether repeated nose-up or nose-down trim changes both the indicator and the aircraft's pitch tendency. A noisy elevator axis or constant pressure on the yoke can mask that effect even when trim itself is working.