Overhead Light Air

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dant
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Overhead Light Air

Post by dant »

Flying back from Mountain High on Friday I noticed a cool breeze over my shoulder. With both of the overhead air vents closed, it seems that there's a decent amount of air that leaks around the switches for the overhead lights. Is this a known thing, or something I should investigate?
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Chris
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Re: Overhead Light Air

Post by Chris »

It's a known problem. There are a few older topics on the forum about air leaks from the overhead vent area:

Overhead vents leak air
Overhead light repair
Maximum cabin heat output
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dant
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Re: Overhead Light Air

Post by dant »

apparently I searched the exact wrong phrase, thanks!
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Chris
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Re: Overhead Light Air

Post by Chris »

dant wrote: Mon Jan 17, 2022 8:57 pm apparently I searched the exact wrong phrase, thanks!
The forum search box is hit-or-miss. I often have better luck using google by adding site:diamondaviators.net to the search terms.
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blsewardjr
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Re: Overhead Light Air

Post by blsewardjr »

Diamond has on OSB for improved map lights and sealing - 40-092 -- http://support.diamond-air.at/fileadmin ... lights.pdf
Bernie Seward, IR, AGI
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Rick
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Re: Overhead Light Air

Post by Rick »

blsewardjr wrote: Mon Jan 17, 2022 11:58 pmDiamond has on OSB for improved map lights and sealing - 40-092 -- http://support.diamond-air.at/fileadmin ... lights.pdf
Before I ask Diamond, does anyone have a copy of this Work Instruction (WI-OSB-40-092) for this service bulletin already?

Thanks!
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dant
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Re: Overhead Light Air

Post by dant »

Crazy that they weigh almost a pound more!
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Rich
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Re: Overhead Light Air

Post by Rich »

dant wrote: Tue Jan 18, 2022 8:08 pm Crazy that they weigh almost a pound more!
Are you looking at something else? The original light fixtures are superseded and the new part (I have one) is heavier, though I don't know how much. But the covers for the original ones only weigh 1 oz. ea. In fact the fixtures combined with the cover weigh in at 3 oz. each.

Installing the covers is not hard EXCEPT for the removal of the fixtures. I have really struggled with releasing the retainer spring (shown below) and in fact have broken one of these fixtures trying to get it out.
Interior Light Fixture.jpg
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Re: Overhead Light Air

Post by mhoran »

There is a winterization kit for the DA40. This includes two baffles; one for the engine, which I've never found the need to install. The other installs under the pilots side wing and blocks the air vent that feeds in above the map lights and into the passenger overhead vents. The latter is incredibly important in the winter months where it gets cold; otherwise the air will seep through no matter what you do. The recommendation is to install these baffles below 59 degrees.

As mentioned there is a seal around the lights themselves. This seal does eventually deteriorate and allows air in through the light fixture itself. It's also possible that the silicon or sealant around the light has been removed over time due to maintenance; that is the case in my airplane. However, despite the deterioration of the seal, installing the baffle keeps my cockpit nice and warm in the cold winter months. Without that baffle, though, it's quite brutal.
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dant
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Re: Overhead Light Air

Post by dant »

In fact the fixtures combined with the cover weigh in at 3 oz. each.
I just read the OSB, and mentally ballparked 333g as a little under a pound.
I.10 Mass (Weight) and CG
This installation results in a mass increase of approximately 333 g
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