TEST PORT AIR BOX PRESSURE
Air box pressure should be recorded in inches of mercury using U-tube
When using air box drain as source for this pressure test, be sure drain is clean
and clear of obstructions.
To check air box pressure on engines with drain tubes or hoses, use air box
covers with a tapped hole and hose fitting.
The following procedure is typical for both port and starboard engines.
Remove air box drain hose (Figure 3, Item 2) from air box check valve (Figure 3, Item 1).
Figure 3. Air Box Drain Hose.