Replace stall warn unit?

[DaveF]

It would be nice to find CAR3 justification for making the change, but just the fact that Cessna switched helps make the case. I've had good luck in the past getting FSDO approval for modifying systems to later-model designs. I changed my 210 from a voltage regulator to an alternator control unit, which required some non-trivial wiring changes. It went smoothly because the supporting documentation consisted of pages from the later model parts and maintenance manuals. It also helps that my IA has a good working relationship with the FSDO.

[GAHorn]

I think I'll channel my inner blueldr and say, "Who's going to know the difference?"

You get ramp checked by the fuzz, are they going to have the information readily available regarding the SWH cockpit notification device to be able to ground your airplane right there? These airplanes have all been so heavily modified over the years that unless they are as in tuned with the airplanes as we as a group are, there are things that could very well slide. If your airplane is spotless (like many on here are), I don't think there will be enough suspicion raised to warrant further investigation. Rather simplistic, I know, and I have seen what can get an airplane grounded and in many cases, it's ridiculous.

Does anybody care to tackle the question as to why the SWH is not required equipment for seaplane?

I was ramp checked by FSDO at Houston not too long ago. When the inspector asked to see my registration and airworthiness certs I handed them to him and the folded, AFM with them fell out of his hands. He picked it up and looked at it...and asked if I had the REST of the "document". (He expected a pamphlet of some sort, not realizing the single/double-sided document was not the entire flight manual.)

The B-model airplane had such benign stall buffet and such slow speed due to it's flaps that the stall warning was required. The seaplane gives lots of "shudder" and "buffet" thereby meeting the rule. < my guess.

[n2582d]

The TCDS for the 170B calls for "Stall warning kit in accordance with Cessna dwg. 0511062" The part number for the early stall warning on the early 170B is 0511062-2. The later 170B has the stall warning hidden behind the glovebox. It is part number 0511062-10.

170B Stall Warning.jpg

As far as I could find CAR 3 doesn't mention anything about a visual stall warning requirement. CAR 3.120 (f) states:

Stall Warning.jpg

As an IA I wouldn't have any problem updating my '52 panel to have the stall warning mounted as on the later 170s behind the glove box. See if your IA and/or FSDO agrees. An alternative would be to do a minor alteration by mounting the buzzer on the back of the glovebox wired to a panel-mounted red light.

[GAHorn]

That's a good catch, Gary. I'd forgotten about the later mounting.

[Bruce Fenstermacher]

Well well well. Love it when the brain trust talks things through and comes up with a pretty iron clad answer. Cessna themselves complied with the rule with "a clear and distinct warning" which obviously did not include a light.

[DaveF]

Thanks for doing the research, Gary. That's a better result than I'd hoped for.

Thanks to all for the discussion!

[n2582d]

You're quite welcome. It was a surprise to me to find that buzzer relocated behind the glove box on s/n 26996 and on 170s. Curious too that they didn't keep the buzzer sans light in the same location. Since Cessna replaced the light/buzzer with a cover they didn't move it for more instrument panel space. Guess they were annoyed by not only the light but also by the noise and decided to mute it by relocating the buzzer.

Covered Hole.jpg