PPRuNe Forums - View Single Post - Police helicopter crashes onto Glasgow pub: final AAIB report
Old 21st Nov 2018, 18:18
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RVDT
 
Join Date: Nov 2006
Location: After all, what’s more important than proving to someone on the internet that they’re wrong? - Manson
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When the cavitate (they heat up) they show a warning.
Nope.

The standard practice seemingly being to select the offending pump OFF to extinguish the caution.
And nope again.

The logic in the CPDS is as follows:

Power is applied to the pump via the CB and the corresponding switch and the CPDS internals measure the current via a shunt. A functioning pump with fuel under load requires a certain current.

If after ~ 3 minutes the current is less than the required value the Caption will illuminate on the CAD. If the current value is restored the caption extinguishes immediately and the "watchdog" timer starts again.

You will notice this if you turn the pumps ON on the ground the caption will go out immediately and when you turn the pumps OFF it takes ~ 3 minutes.

The only way to extinguish the caption on the CAD is to have an operating pump transferring fuel. Every time the caption illuminates you will get a Master CAUTION which can be reset but the corresponding caption
on the CAD remains until the situation meets the logic. Doesn't matter what you do with the switch. If the logic is not met the CAD caption is active.

All Master CAUTIONS should be acknowledged and reset so they do not mask the subsequent ones.
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