HAWK21M From India, joined Jan 2001, 31775 posts, RR: 55 Posted (7 years 4 months 2 weeks 5 days 9 hours ago) and read 3130 times:
Its that same type of Question which AMMs can't answer & the ones that can are the Manufacturers or people that know about the development stages of the Aircraft type.
On the P8 panel of a B757,any version,not sure how its on the B767s.
The Fire test panel on P8 has a test button for "ENG" & "ENG/APU/CARGO"
Why is the ENG test button duplicated.Was there a reason for Boeing to do that.As both Tests test the ENG Fire/Overheat Elements.
Or was it to isolate a Fault.
TristarSteve From Sweden, joined Nov 2005, 4161 posts, RR: 33
Reply 1, posted (7 years 4 months 2 weeks 5 days 9 hours ago) and read 3125 times:
Quick answer without reading but
Eng APU Cargo tests the fire warning circuits.
ENG tests the overheat system for the internal cooling air. 4 thermocouples that measure that the internal cooling air is too hot. The effect to the flight crew is the same, they get a fire warning, but the warning comes from a totally different place, and the separate test switches help you to find which one it is..
A/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 3
Reply 4, posted (7 years 4 months 1 week 5 days 4 hours ago) and read 2843 times:
isnt the ENG/APU/CARGO test switch the AFOLTS system where as the ENG just does the Turbine OVHT detectors ? the turb detectors on the L/H side of the turbine case around 9 o clk ALF. The ENG switch is seperate in some way im sure but ive slept since working on 757's last.