Voyant ambre OFF — Equipment Cooling (non-EFIS / EFIS SUPPLY·EXHAUST).Amber OFF light — Equipment Cooling (non-EFIS / EFIS SUPPLY·EXHAUST).
ObjectifObjective
Comprendre les configurations non-EFIS vs EFIS, les bus d’alimentation, et pourquoi un capteur sale allume OFF autant qu’un fan en panne.Understand non-EFIS vs EFIS configurations, power buses, and why a dirty sensor illuminates OFF as much as a failed fan.
Panneaux Equipment Cooling — non-EFIS (un switch) vs EFIS (Supply + Exhaust).
Trois causes d’allumage du voyant OFF.Three causes of OFF light illumination.
(*) Le débit massique d’air peut chuter pour plusieurs raisons :(*) Mass airflow can drop for several reasons:
panne du ventilateur de refroidissement ;
filtre à air colmaté ;clogged air filter;
capteur de débit sale (détection low flow intempestive / spurious) ;dirty flow sensor (nuisance / spurious low-flow detection);
décompression (ΔP inlet/outlet qui chute).decompression (inlet/outlet ΔP collapsing).
Exhaust Fan (normal) fail peut venir d’un Ground Service Bus 115 v ac unpowered.Exhaust Fan (normal) fail can come from an unpowered Ground Service Bus 115 v ac.
Supply Fan Normal + low flow detect (as wired) sur Battery Bus 28 v dc — BAT BUS fail = cooling perdu sans voyant OFF ; SG overheat → Supply Alternate.Supply Fan Normal + low flow detect (as wired) on Battery Bus 28 v dc — BAT BUS fail = cooling lost with no OFF light; monitor temperatures.
In FLT
WX-Radar OFF auto — WXR DSPLY / EXCESS DATA
IRS : 180 min sans cooling — ne pas couper IRU
TR max sans forced air : 50 A — monitorer
Cargo : land nearest suitable (Cargo Smoke Detection)
NNC : si voyants restent — pas d’autre action exigée ; note MEL 21-27NNC: if lights remain — no further action required; note MEL 21-27
(EFIS) both supply ou both exhaust INOP : > 90 min → perte avionics essentielles
MAIN SMOKE NO FLOW (as installed) : low flow upper cargo → nearest suitable
NORMAL MODE
GND / FLT ΔP < 2.5 PSI : exhaust belly. Prévol AC ON : vérifier airflow dessous. Valve coincée : quelques coups juste devant le trou d’échappement.GND / FLT ΔP < 2.5 PSI: exhaust belly. Preflight AC ON: check airflow underneath. Stuck valve: a few taps just aft of the nose gear.
ΔP ↑ → Flow Control Valve ferme ; air E&E chauffe fwd cargo. Rouvre à 2.0 PSI idle descent. Vibrations légères ≠ elevator tab / flap LED.ΔP ↑ → Flow Control Valve closes; E&E air heats the fwd cargo. Reopens at 2.0 PSI idle descent. Light vibrations ≠ electrical fault.
Fwd cargo ≥ 5 °C / 40 °F ; aft ≥ 0 °C / 32 °F (hors portes). AVI warm-blooded : bay 1, loin de la porte.Fwd cargo ≥ 5 °C / 40 °F; aft ≥ 0 °C / 32 °F (doors closed). Warm-blooded AVI: bay 1, away from the door.