The whole point of a Constant Speed Drive is to do just that.... hold the frequency within a set tolerance. Without looking, 400Hz +/- 10 Hz.

If the frequency drifts higher or lower that 390/410Hz. The Generator Control Unit will take it off line.

These units a pretty damn reliable. 397-403 is usually seen as a frequency.

If you're reading low freq's, the CSD is NOT doing its job.

If the frequency is showing low, but generator is "not" dropping off line, you need to be verifying the indication system.

I have never seen an indication that was wrong when the generator is staying online.

You would be looking at a bunch of areas of possible faults, not just grounds.

Do you have any idea on what may cause frequent low frequency indication of constant speed drive? Can it be also be a false indication which is attributed to improper grounding/bonding?

They want to deactivate it while doing as little work as possible, the switch being there won't affect any operations. Agian also easier to reactivate if that is the desire of the operator.

Do you have any idea on why Boeing doesn't ask removing switch per service bulletin for airstair removal?

Was getting sick of digging through the bag of pins in the door for the gear pins, so I created a 3d print model of a gear pin holder to make them easier to find. Made like the ones that come on the 650 not sure if this originally came with the aircraft and was lost or they never had one. Either way this fits the pins quite well, will have to see how it holds after time may need to change material after all the hot and cold cycles.

Printed : PLA
Print Time : 1:45
Print Cost : .25 

 
 

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I cannot answer your question. That is a engineering and quality control issue.

I am a mechanic. I choose to be a mechanic because I don't want to ever have to deal with these types of problems. Higher-ups deal with this..... not me.

The problem is that for some components such as "forward airstair assy", neither of tabulated part numbers apply to current fleet. Does it mean the airstair assy should not be removed to accomplish the SB??!!!