Lower aft cargo heat comes from bleed air taken from the center section of the bleed air duct. This hot air is directed into the cargo area to raise its temperature as needed. Temperature is controlled automatically by a thermal switch that senses the cargo bay temperature and modulates a valve: when the bay is cool, the switch opens the valve to allow bleed air in; when the bay warms, the switch closes the valve to reduce or stop the flow. This automatic regulation maintains the desired temperature without using electric heaters or relying on passenger cabin air.

Auto-relight protection is tied to the engine’s monitoring of combustion health. The control logic triggers ignition to try to re-light when the Exhaust Gas Temperature reaches or exceeds its preset limit. This threshold-based signal ensures that, if flame is lost or combustion cannot be sustained (flameout or rollback), the igniters are energized to attempt a re-light and restore stable operation. It isn’t limited to water ingestion or maintenance tests, and it isn’t based on flameout detection alone without the EGT limit being reached.

The question is about how the AFDS stabilizes the airplane when an engine fails before the approach. In an engine-out condition, the airplane has a natural yaw and roll tendency from the asymmetric thrust. To keep the approach stable and keep the wings level, the AFDS is programmed to transition into a wings-level sideslip at a specific point in the descent. That transition occurs at about 1300 ft AGL. This timing gives enough vertical room and control authority to bleed off the asymmetry, align with the intended flight path, and maintain a stable, wings-level configuration as you continue the approach and prepare for the final descent. Beginning the sideslip too low would risk getting to the runway with insufficient margin to reconfigure the flight path safely; starting too high would delay stabilization and could require more aggressive control inputs closer to the runway. So, when an engine fails prior to the approach, the aircraft’s AFDS will introduce a sideslip to wings level at 1300 ft AGL to promote a safe, stable approach configuration.

Approach data for the ISFD comes from the left approach receiver. This channel decodes the localizer and glideslope signals (and handles GLS data when applicable) and supplies the ISFD with the approach course, deviation, and glide-path information it needs to display approach cues. The right approach receiver acts as a backup or serves other systems, but the ISFD’s primary source for ILS/GLS data is the left receiver. The ISFD does not generate this data itself; it relies on the approach receiver network for the information.