[stackj]

It does sound to me that the hose you are talking about is for avionics cooling. As was stated in an earlier response, there is an AD to put a Y fitting in that line and run a piece of tubing to the engine gage cluster for cooling of the fuel gauges... (They had a tendancy to turn into smoke). A number of 337s have had a different gauge cluster installed which is manufactured by Mitchell Instruments. If your aircraft has the revides gauge cluster (each gauge an individual instrument which plugs into an installed rack), there was no need to keep the cooling tubing and nozzle in place. Most of the aircraft modified has the added cooling equipment removed when the modification was installed. There is no STC for the mod, but several have been installed via field approval.