I've circled an intake in red on the images below. I am working on a 737 NG and I don't know what it's for. I am thinking it's a pressure probe for APU control but I am not sure.

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Front view: comparing location to aft door confirms it's the same "device." (Full image.)

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    $\begingroup$ When you say "working on" a 737NG, are you actually performing maintenance on it? If so, have you opened the maintenance manual for that aircraft? Further that point, why are you not asking the senior 737 A&P mechanic at your company? If you are building a model, this question makes more sense. $\endgroup$ Oct 6, 2016 at 17:31
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    $\begingroup$ Please provide in image source $\endgroup$
    – TomMcW
    Oct 6, 2016 at 18:01
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    $\begingroup$ No, it is not a probe, it is called APU AIR INLET SCOOP and it's purpose is to cool/vent the area between the APU insulation blanket and the bulkhead. See AMM 49-10 (SDS) and AMM 49-17 (PP). $\endgroup$
    – Radu
    Oct 6, 2016 at 21:18

1 Answer 1


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The APU insulation panels are not easily damaged, however, it the panels are punctured, you should repair the damaged panel as soon as possible. If you do not repair a puncture immediately, the panel can store fluids in the insulation. If fluids get into the insulation material, you must replace the panel. The air inlet scoop replaces the foam and support insulation (egg crate) that were installed between the APU insulation panels and the bulkhead. During an airplane operation, the air inlet scoop supplies forced outside air through the empty space between the APU insulation panels and the bulkhead for ventilation and for the removal of flammable or unwanted fluids. The location of the air inlet coop is behind the forward insulation panel and adjacent to the forward right side of the APU cowl door.

Source: Boeing training manual

  • $\begingroup$ Sorry, my dear... friend, that item it is as simple at it looks-just a simple scoop doing a very basic job: venting. It is very clear in the text posted above. That's it, nothing else (ah, a last thing, the source of these informations is the B737 Technical Training Manual-if you want one, talk to Boeing). $\endgroup$
    – user17371
    Oct 7, 2016 at 23:09

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