Posts about: "RUN/CUTOFF" [Posts: 202 Page: 11 of 11]ΒΆ

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Pilot DAR
February 03, 2026, 17:57:00 GMT
permalink Post: 12031742
Oh look, we found a fuel cutoff switch problem on another one of our fleet
I read a report of a problem. I'm not sure that I actually see a report that there truly was a problem.

Preceding a "however" This was reported:

“Both left and right switches were checked and found satisfactory, with the locking tooth/pawl fully seated and not slipping from RUN to CUTOFF. When full force was applied parallel to the base plate, the switch remained secure.
If a "however" is written after that statement, it is either meaningless and to be ignored, or it has the effect of negating the statement. There is no "partly airworthy" for these switches. It can't be both statements. Thus, my doubt about the credibility/applicability of this whole situation in the context of the 171 crash, subject to these two statements being reconciled with each other.

Subjects Fuel (All)  Fuel Cutoff  Fuel Cutoff Switches  RUN/CUTOFF

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MechEngr
February 03, 2026, 21:24:00 GMT
permalink Post: 12031849
Originally Posted by Musician
I imagine one way for this to be true would be if the lever has some wiggle room, such that the teeth on it can move sideways past the teeth on the base, and then stick in that position where the lever is up and the flanks of the teeth are still touching. In that position, you could flip the switch back off without overcoming the detent. But if you operate the switch properly, with no sideways force, and seat the lever correctly in the ON position, then it'd be secure. That fits with the part of the press release about telling the pilots how to operate these switches properly.
There are two teeth on the switch body and two teeth on the plunger that is pulled up to unlatch the switch. There is not enough room for a tooth on the plunger to fit between the switch toggle and the mating tooth on the switch body. It would require the toggle axle pin to break to allow that, allowing the toggle to fall off and the plunger with it.

Clearly the design of the latch requires that it move from one position to another position with some applied forces. Absent some clarification of what the pilot(s) did or observed, their statement matches the way the switch is supposed to function.

" However, applying external force in an incorrect direction caused the switch to move easily from RUN to CUTOFF, due to the angular base plate allowing slip when pressed improperly with finger or thumb.\x94

The problematic part of the statement is that there is nothing that says what they think the incorrect direction is. But, if one wants it to move it must be pushed in a direction that is incorrect for it to remain locked in position. It is almost certain that if one pushes towards the opposite position from the current locked one and, at the same time uses the friction from that push, one can pull the plunger up and disengage the lock.

Is that what they meant by "incorrect direction"? Who, besides them, know what they meant?

Subjects Fuel (All)  Fuel Cutoff Switches  Fuel Cutoff Switches (detent)  RUN/CUTOFF

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