grumman aa-5 stall warning delay

On Jan 5, 11:45*pm, wrote:
H@mst3r wrote:
no, it moves freely and has just been rebuilt by our AMO.

Brand new case for someone to investigate

The stall warning on Grummans is a spring loaded vane screwed to a switch..

When the airflow where the vane is mounted starts flowing up, the
switch closes and the alarm sounds.

It is impossible for there to be a delay between the switch closing
and the alarm sounding.

That leaves either the vane being bent, positioned incorrectly or a
too stiff of a spring, thus requiring being deeper into the stall before
the switch closes.

I would question how the switch could be "rebuilt" locally as the switch
is proprietary and not generally available as a part.

--
Jim Pennino

Remove .spam.sux to reply.

Most likely it's the buzzer. Some of those were a small
electromechanical horn, which uses a small coil, a diaphragm and a
switch on the diaphragm that opens the coil's supply when it's
displaced. The resulting oscillation makes lots of noise. When that
switch gets dirty, it might be a few seconds before the diaphragm gets
around to moving enough to start the oscillation. Probably need a new
horn. The other possibility is a bad connection somewhere in the
circuit, most likely the ground connection at the horn.

Dan

wrote:
On Jan 5, 11:45Â*pm, wrote:
H@mst3r wrote:
no, it moves freely and has just been rebuilt by our AMO.

Brand new case for someone to investigate

The stall warning on Grummans is a spring loaded vane screwed to a switch.

When the airflow where the vane is mounted starts flowing up, the
switch closes and the alarm sounds.

It is impossible for there to be a delay between the switch closing
and the alarm sounding.

That leaves either the vane being bent, positioned incorrectly or a
too stiff of a spring, thus requiring being deeper into the stall before
the switch closes.

I would question how the switch could be "rebuilt" locally as the switch
is proprietary and not generally available as a part.

--
Jim Pennino

Remove .spam.sux to reply.

Most likely it's the buzzer. Some of those were a small
electromechanical horn, which uses a small coil, a diaphragm and a
switch on the diaphragm that opens the coil's supply when it's
displaced. The resulting oscillation makes lots of noise. When that
switch gets dirty, it might be a few seconds before the diaphragm gets
around to moving enough to start the oscillation. Probably need a new
horn. The other possibility is a bad connection somewhere in the
circuit, most likely the ground connection at the horn.

Dan

If it were a bad connection somewhere, it would likely not work at all.

This is easy to test:

1. Turn on master switch.

2. Press on vane with finger.

If the horn sounds, everything is electrically OK.

As to what the noise maker is, I would have to look in the maintenance
manual, which is at the hanger.

According to the AYA Maintenance Compendium, the switch in the assembly
is only available from the assembly manufacturer and can only be
"rebuilt" by the manufacturer, which leads me to believe if the assembly
was "rebuilt" locally, then a switch was used that happens to fit
mechanically but has the wrong spring tension, thus delaying switch
closure.


--
Jim Pennino

Remove .spam.sux to reply.

I know someone who told me about someone who repaired an intermittent
electrical stall horn by resoldering a cold connection. It's worked fine
ever since -- so I hear. g

wrote in message
...
On Jan 5, 11:45 pm, wrote:
H@mst3r wrote:
no, it moves freely and has just been rebuilt by our AMO.

Brand new case for someone to investigate

The stall warning on Grummans is a spring loaded vane screwed to a switch.

When the airflow where the vane is mounted starts flowing up, the
switch closes and the alarm sounds.

It is impossible for there to be a delay between the switch closing
and the alarm sounding.

That leaves either the vane being bent, positioned incorrectly or a
too stiff of a spring, thus requiring being deeper into the stall before
the switch closes.

I would question how the switch could be "rebuilt" locally as the switch
is proprietary and not generally available as a part.

--
Jim Pennino

Remove .spam.sux to reply.

Most likely it's the buzzer. Some of those were a small
electromechanical horn, which uses a small coil, a diaphragm and a
switch on the diaphragm that opens the coil's supply when it's
displaced. The resulting oscillation makes lots of noise. When that
switch gets dirty, it might be a few seconds before the diaphragm gets
around to moving enough to start the oscillation. Probably need a new
horn. The other possibility is a bad connection somewhere in the
circuit, most likely the ground connection at the horn.

Dan