09 — Humidity, water and fluids: qualify the exposed assembly
DO-160 Display Qualification | A-P02 — Draft / Not Released
Learning objective: Select exposure faces and acceptance criteria for Sections 6, 10 and 11.
Photo: Cjp24 · Environmental chambers · CC BY-SA 3.0. Original image, displayed at reduced size.
Three different questions
Humidity evaluates moisture exposure over a prescribed cycle. Waterproofness addresses selected liquid-water exposures. Fluids susceptibility assesses specified chemical contacts and their consequences. Passing one does not establish the others. A front-sealed touch display can still have vulnerable rear connectors, a hygroscopic optical bond or a coating attacked by cleaners.
Numerical reference points
DO-160G Section 6 high-humidity phases use 95 ±4% relative humidity. Category A uses a 50 ±2 °C high phase and two 24-hour cycles; B uses 65 ±2 °C and ten cycles; C uses 55 ±2 °C and six cycles. The complete cycles contain changes in conditions: describing them as a constant high-temperature soak misstates the method. Use the applicable cycle figure, conditioning and timing in the standard.
Follow the moisture path
Identify the surfaces actually exposed after installation. Record display angle, drainage, seals, connector backshells and any covers or barriers. If a fixture blocks an opening that is exposed in service, it can invalidate the representation. Where a face-only requirement is intentional, state the excluded surfaces in the claim and installation instructions.
For fluids, identify the chemical, concentration, temperature, contact method, duration, cleaning or drying procedure and subsequent checks required by the selected method. If the operator uses a particular disinfectant, determine whether it is within the contracted fluid set. A vague claim of cleaning-fluid resistance does not address every formulation.
Display-specific checks
Look for haze, delamination, coating damage, discoloration, label loss, touch false activations, leakage and corrosion. Define when optical measurements occur: a wet surface can behave differently from a recovered dry surface. Record both required in-exposure behavior and the prescribed post-exposure evaluation; neither substitutes for the other.
Exercise
A water test used a protective rear cap absent from the proposed aircraft installation. Worked response: either substantiate an equivalent installed protection, revise the installation to include the qualified protection, or test the affected configuration. Do not remove the cap from the report's equipment list and continue using the original claim.
Humidity conditions: nominal cycle and required tolerances
| Item | A | B | C |
|---|---|---|---|
| Initial stabilization | 38 ±2 °C; 85 ±4% RH | 38 ±2 °C; 85 ±4% RH | 38 ±2 °C; 85 ±4% RH |
| Rise | 2 h ±10 min | 2 h ±10 min | 2 h ±10 min |
| High-temperature phase | 50 ±2 °C | 65 ±2 °C | 55 ±2 °C |
| High-humidity hold | 95 ±4% RH; ≥6 h | 95 ±4% RH; ≥6 h | 95 ±4% RH; ≥6 h |
| Return phase | 16 h ±15 min | 16 h ±15 min | 16 h ±15 min |
| Return conditions | Gradual decrease to 38 ±2 °C or lower; keep RH high and ≥85% | Same | Same |
| Cycles / nominal exposure | 2 / 48 h | 10 / 240 h | 6 / 144 h |
| Final powered evaluation | Drain moisture, do not wipe; apply power within 1 h; warm-up ≤15 min; then required checks | Same | Same |
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