Gear Motor & Light

[Kevin McDonnell]

Dave,

I got a chance to read the maintenance manual this evening. From what I understand of the schematic, it looks like you cannot get an "up light” indication if the pressure switch has not tripped (it's "open" when there's 1500 PSI present). If this pressure is not sensed, then it grounds the voltage that otherwise would have illuminated the up or down lights.

Since the symptom involves the motor running continuously, I think the pressure switch is the first place to look (vs. the uplock switches). It can be disassembled, cleaned, and adjusted (with shims) to set it to trigger at the desired pressure. The bottom line is that you need to figure out if the correct pressure is being achieved and not sensed, or it’s not being achieved.

The book also points out that the gear system is very current hungry (30 amps starting & 20 amps running) and somewhat sensitive to low voltage. You may find that running it on the ground off of a healthy mule gives you good voltage, but due to dirty connections/corrosion etc., in flight the plane’s electrical system may not be providing the same voltage.

Let us know what your mechanic finds.