HYDRAULIC CONSUMERS AND COMPOUND FAILURE EFFECTS
The distribution drawing matters as much as the pump drawing. Flight-control surfaces use actuators supplied by selected circuits, while landing gear, braking, steering, reversers and cargo-door functions have their own dependencies. A system loss should therefore be translated into retained functions, not simply into a missing colour on HYD. The same broad failure label can leave different operational consequences when a configured steering source or alternate braking path changes the surviving arrangement. [71, PDF p. 7] [87, PDF pp. 44–47, 88–92]
Normal braking and the gear system do not share every supply with alternate/parking braking. The reference architecture separates Green normal braking from Yellow alternate/accumulator paths. This is why a hydraulic loss can degrade stopping functions without producing the same result as a loss of all brakes. A functioning hydraulic source also does not guarantee anti-skid or autobrake, whose electronic control and sensing must remain available. Preserve the distinction between actuator power, controller function and the commanded mode. [87, PDF pp. 87–92] [89, PDF pp. 2–6]
A control surface may retain one hydraulic actuator while losing another, or continue to move under different computer/law authority. An apparently normal short control movement does not establish unchanged redundancy, rate capability or protection. The F/CTL page and the remaining failure/status information have to be interpreted together. Multiple hydraulic-system losses can also produce control-law reconfiguration; the exact mapping belongs to the applicable aircraft standard. Do not extrapolate a single-system training result into a dual-system emergency without reviewing that specific combination. [73, PDF pp. 6–18, 27–33] [71, PDF pp. 6–7]
Cargo-door use is another example of a local demand influencing a common resource. In the reference architecture the Yellow electric/manual provision permits door operation with engines stopped, with associated hydraulic logic. An audible pump during servicing therefore does not necessarily mean the main airborne configuration was selected. Establish the active ground operation before diagnosing a pump sound or changed pressure. Fenix documents selected hydraulic/steering options, but this chapter does not assert that every maintenance isolation, hand-pump function or priority-valve failure is independently implemented in the simulator. [71, PDF pp. 2, 8–10] [70, Available Options: hydraulic pump and steering-source settings]