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Piper Aztec Right Nacelle Vent

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Well-known member
Sep 18, 2003
Anyone know what the purpose of the upper right nacelle fish gill type vent is on most 70-80's era Aztecs? They're usually hinged and cam'locked for, it looks like oil cooler access but the left engine has no such vent...
What differences are there between the right side and the left side? Could be to cool something off maybe? A picture might help if you have one.
It's only on the right side, the same on every one I fly. The oil coolers are the same on both sides. About the only differance is exhaust exit placememnt but that wouldn't change things. Someone thought it was to cool the turbo on turbo aztecs like in the Navajo but why not have one on the left cowl? It did save my ass one night when I cought the begining of a big fire back there...
If the Aztec is like some other Piper twins, the extra louvre on the RH cowling is probably to allow more cooling because the RH engine is the one that drives the air conditioning compressor. I don't have the number handy, but Piper issued a SB to modify RH cowlings by adding additional louvres on Navajo's for this reason.
R/H Vent

The louvered panel adjacent to the poil cooler on the right engine of later model Aztecs was an attempt at a bandaid fix to those engines running high oil temperatures. I flew a lot of Aztecs without the vent and on hot days at high weights it was necessary to trail the right cowl flap to control oil temperature. The lovers do help. There is a Piper modification to install a larger cooler. The root cause of the problem is too small a cooler. Charlie Melot Zephyr Aircraft Engines
Awsome, that makes sense. I have the modified oil coolers on both sides and the right one runs cooler now. Thank's for the input. Sure wish I had AC last week coming home from OSH with five smelley guys.

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