16 — Electrostatic discharge and accessible display surfaces

DO-160 Display Qualification | A-P02 — Draft / Not Released

Learning objective: Define Section 25 locations and monitor display and control responses.

Start with what a person can touch

The display bezel, glass, controls and exposed conductive features can provide discharge paths. Define accessible locations under the installation assumptions. Touch sensing adds a second concern: the display may continue to show an image while issuing a false command or losing touch function. Monitor both the visual output and control outputs.

DO-160G Section 25 uses 15 kV air discharge, with ten positive and ten negative discharges at the selected accessible locations under its procedure. This is not a connector-pin injection test. The full method defines the setup, application and performance evaluation; use it for qualification rather than substituting an IEC contact-discharge procedure based on a similar headline voltage.

Representative construction

Include the production optical stack, coatings, bezel bonding, seals, cable interfaces and touch-controller firmware. A temporary grounded foil or bench earth lead may create a discharge path absent from the aircraft. Conversely, a fixture without the prescribed bond can create an artificial failure. Document both and assess their effects.

Define allowed consequences

If the required function must remain uninterrupted, a reset is not made acceptable by automatic recovery. If a requirement allows a defined temporary degradation, state its maximum duration, indication and recovery condition. Record image artifacts, false controls, link errors and latent effects as well as obvious resets.

Exercise

A display remains bright after discharge, but the touch output issues one unintended activation. Worked response: compare against the control-output and system-function criteria. The visual observation alone is insufficient. Preserve the stimulus timing and output event, investigate the path and retain both the original failure and any retest evidence.

Practical monitoring record

Map discharge locations to photographs or an identified drawing, record polarity and count, log operating mode, and retain functional observations with timing resolution. Document any location inaccessible in the installed state and the rationale for its treatment. Do not turn a test-location omission into an unstated limitation after the test.