I need an answer in reference to 14 CFR 23.207. I looked there and couldn't say 100% if it was a yes or a no.
2 Answers
No, many aircraft don't have them, like the Cherokee since it uses a gear warning horn. The horn signifies that the gear isn't down and you don't want to confuse that with the stall warning, so they don't have one.
23.207 says that an audible or visual indication is not required as long as the aircraft exhibits a "warning" 5 knots before the stall, in the case of the Piper Comanche the warning that satisfies the requirement is the stall buffet.
The relevant section of 23.207 is part (b):
(b) The stall warning may be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the crew within the cockpit is not acceptable by itself.
So the stall buffet, as long as it is pronounced, is adequate indication of a stall to satisfy 23.207.
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$\begingroup$ At least some Cherokees also have a red light on the instrument panel as a stall warning. $\endgroup$ Oct 25, 2019 at 7:53
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2$\begingroup$ @Bianfable The one I flew did not. Either way the regulation says that a "visual stall warning device ... is not acceptable by itself". $\endgroup$ Oct 25, 2019 at 11:29
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1$\begingroup$ Most, perhaps all, Cherokees have fixed gear. (The PA-28R models are usually called the Arrow, I think.) Mine (1965) does have the red light on the panel as the stall warning, but it's very easy to feel the onset of a stall without it. $\endgroup$– jamesqfOct 26, 2019 at 4:33
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$\begingroup$ @jamesqf You're right, I was thinking of the Comanche, not sure why I said Cherokee. $\endgroup$ Oct 26, 2019 at 15:33
The answer above is just flat-out wrong. It makes no difference whether or not certain airplanes have them or not when it comes to airworthiness.
The real answer is it depends...
91.205 does not include a stall horning but that doesn’t mean the Type Certificate Data Sheet for the plane you are piloting contains something different.
For example, a Cessna 172’s TDC (3A12) explicitly states that a stall warning horn is REQUIRED for the plane to be, well, a Cessna 172. Therefore if you are about to take off in a 172, you technically need an operational stall horn to be airworthy.
Generally speaking, you need to consult 91.205, the TDC for the plane, any STCs (supplemental), and then the MEL from the POH and probably in that order.
I highly recommend listening to the Max Trescott’s Aviation News Podcast episode 151 on airworthiness where they go through how to determine if a piece of equipment is required or not (hint: they talk about the stall horn!).
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1$\begingroup$ I fail to see where the contradiction in your answer relative to the one of Ron is. Yes, a stall warning horn is required for the 172, but not for the Arrow. Since the question is about 23.207 (and not the 172), Ron's answer is correct. $\endgroup$ Nov 24, 2020 at 3:10
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$\begingroup$ I guess I’m confused - where does the original question specify a Piper anything? Ron’s question is correct for the plane he mentioned. But you MUST MUST look at the type data certificate sheet as part of your SOP when dealing with inoperative or missing equipment. I gave the 172 as just one example where applying the original logic would yield the wrong answer. The person asking this question may switch planes, apply Ron’s logic, and be 100% illegal. I kind of find it funny i got downvoted for the correct answer. $\endgroup$– pisymbolFeb 7, 2021 at 13:18
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$\begingroup$ First, I did not downvote your answer. Second, Ron's answer is correct, apart from the Comanche - Cherokee mixup. Buffeting is considered sufficient if it satisfies 23.205. Yes, the plane requires a horn (and not a 'horning') when the type certificate says it needs one. But that is only a consequence of 23.205. Basically, Ron's answer is the engineer's answer and yours the lawyer's answer. And guess which one is more helpful! $\endgroup$ Feb 7, 2021 at 15:19
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$\begingroup$ I didn’t say you did btw (downvote). I agree about buffeting but If it’s on the type data certificate sheet it’s required regardless how useful the horn actually is or isn’t or this plane doesn’t need it cause of this or that. I DO agree with the fact that Ron’s answer is useful as practical knowledge goes if ultimately not complete from a reg standpoint. $\endgroup$– pisymbolFeb 8, 2021 at 20:42
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$\begingroup$ OK, last attempt. The stall horn has been added in order to certify the 172. Without it the 172 would not comply with 23.207 (not 205). As a consequence of that, it is listed in the MEL. Without the horn the 172 cannot not be operated legally. The question asks whether every airplane needs a stall horn, and buffeting on the Comanche is sufficient to not require one. Ron's answer addresses this point directly and your explanation only explains how to find out whether one is required when certification made one necessary, but not why it has been added in the first place. $\endgroup$ Feb 8, 2021 at 22:36