Page 29 - Volume 13 Number 9

on each side, between the inboard and outboard flap segments. (If the flaps are inspected while they are down, the switches are rather easily located and seen.)
As long as the two – inboard and outboard – flap’s leading edges remain closely side-by-side, as they should, then that side’s split flap switch remains closed. But if one segment fails to move while its neighbor moves correctly, the leading edges are no longer side-by- side and the switch opens. As soon as this occurs, the absence of control circuit power causes the Dynamic Brake Relay to instantaneously stop the motor and the still-operating segments. The POH tells us that the stopping action will take place by the time the flaps are 3°- 6° out of sync. Since full flap extension is 35°, it means we never exceed a 20% differential.
educated guess of the proper speed, somewhere between the Full flap and No flap VREFs.
Before continuing, I need to clarify a minor item. The two split flap protections that I have been discussing did not become actual microswitches until 1979. All of the 300-series use the switches since they appeared later. But the 200-series, prior to serial number BB-425, use a surprisingly odd design. A standard 5-amp cylindrical fuse is mounted within a fuse holder, one with the springy metal clips that hold the fuse. A clamp connects a short wire to the fuse. When the 3°-6° separation occurs, the wire yanks the fuse out of the holding clips, shutting down the circuit. Who came up with that plan?! As funky as it seems, however, it works quite well!
How often do King Airs have split flaps? Almost never. Perhaps of more interest is how often does the Split Flap Protection system malfunction and leave us with inoperative flaps even though the flaps themselves are fine? I have been pleasantly surprised to find that this additional safety feature has proven to be almost 100% trouble-free. Nice!
How do we handle this split
flap condition? We cannot fix the
problem. Until maintenance takes
place, we are stuck with the flap
setting that we now have. The
obvious procedural change we need
to address is to determine and use
a new proper VREF landing speed.
Since the flap position indicator
gets its information from the
right inboard flap segment only,
realize that its position may not
be the best measure of the overall
average extension. “Eyeball” all
of the segments, then make an modified with all of the various
In 1985 I had the pleasure of flying with one of my recurrent training customers to attend the Paris Air Show. His model 200 was one of the first to be
SEPTEMBER 2019
KING AIR MAGAZINE • 27