DIY - Replacing stall warning horn (G1000 DA40)

[Chris B]

Replacing the stall warning horn in the G1000-equipped DA40 is fairly straightforward. The only tricky bit is re-aligning the two flat-heat screws with the mounting bracket, but good lighting and an extra pair of hands will help a lot.

The relevant section of the AMM is 27-39, but the diagrams are not shown - or accurate - for the G1000 aircraft. Rather than mounting horizontally ("pointing" towards the aft section), the horn is directly over the pilot's left knee and mounted near-vertically.

The horn itself is apparently identical to the standard Cessna part. My local Diamond service center recommended using the Cessna part.

Chris

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Tools

• #2 Phillips screwdriver (to remove the instrument panel cover and stall warning horn)
• Optional Hair dryer (to make clear tubing more flexible)

Parts

• Replacement horn: Cessna P/N 0713348-1, ~$26 (link)
• Small zip-tie (to clamp hose onto horn)

Basic steps

1. Remove instrument cover (~12 flat-head screws)
2. Remove two flat-head screws holding horn to lower instrument panel
3. Lift horn assembly out from top of instrument panel
   • Note direction of circular mounting bracket (IOW, which side is "up")
   • Note small nylon check-ball in hose. Do *NOT* lose this!
4. Remove old horn from clear tubing. Heating the tubing with a hair dryer makes this easier.
5. Place bracket IN CORRECT ORIENTATION on new horn, and slide base into clear tubing
   • Be sure that the nylon check-ball is in the hose prior to insertion
6. Zip-tie clear hose onto base of horn
7. Place horn & bracket in position inside the instrument panel.
   • A helper and good lighting really helps here
8. Align the flat-head screws in the bracket and hand-tighten. Don't go crazy.
9. Test the new horn. I use calibrated lips
10. Re-install instrument cover
11. Make appropriate logbook entry

Here are some relevant pics:

The two missing flat-head screws are what hold the horn in-place. Do not remove the third flat-head screw in the upper left of this photo.

This side of the bracket faces inside the instrument panel.

This side of the bracket faces towards the face of the instrument panel.

Note zip-tie and nylon check-ball.

Note hole alignment.

[Chris B]

FYI, here is a comparison between the old horn in my aircraft and the new Cessna equivalent.

Chris

[TangoDelta]

Thank you for the incredible tutorial. This hasn't come up here yet but will I'm sure.

[rwtucker]

I'm in the clouds. What goes wrong with these horns?

[Rick]

I'm in the clouds. What goes wrong with these horns?

Robert, you should NOT be posting to the forum while in IMC!

There have been several threads about broken stall horns, although I'm not sure causes of failure have been identified. Blowing into the hole would probably not do it much good, and I would suspect getting water into the horn through the tubing would be bad (especially if below freezing!). But it seems like such a simple device...

[rwtucker]

Rick: Thanks. I'm going to take a closer look at mine. I could see the ground . . . I swear!

[Chris B]

What goes wrong with these horns?

The little reed stops vibrating properly. I have no idea exactly why the reed fails. But it is not a precision part (basically an "expensive" kazoo). In my case it suddenly failed without warning.

I first noticed when I could not demonstrate the horn sound for a passenger during a pre-flight briefing. And the horn is part of the minimum equipment list. So that was a short flight.

Chris

[carym]

I certainly enjoy reading this thread. Note that I had a stall horn go out in my DA42, and as indicated in a previous thread (http://www.diamondaviators.net/forum/#p44775) the reduced cost for this item was $2000!

[Rick]

My stall horn quit working a couple of weeks ago, so I ordered a new one from Sportys. As noted in this thread (and in the Diamond Parts catalog), it's a standard Cessna part. When I removed the old one, however, there was no check ball in the line. The pin was there to keep it from disappearing down the line, but no ball! And, of course, the new kazoo doesn't come with a new check ball...

So, my question - for those of you who have done this replacement before: what is it made of? I would appear that it's only purpose is to block the horn from any incoming air pressure, but then lift out of the way under enough suction to allow the kazoo to play. Any ideas where one would find a replacement for this little check ball?

[rwtucker]

But . . . where is the ball!