Originally Posted by
Pilot DAR
Easy thing first, replace the vacuum system filter, and check the air supply side of the system for obstructions. If the air source is obstructed/limited, the vacuum pump will pull, and the indicator indicate an adequate vacuum, but the flow of air at that pressure (vacuum) may not be adequate to run the two gyros.
When reading for my AGK exam, I noticed that the Pooley's book suggests that a blocked inlet filter would result in reduced vacuum reading. That does not seem right, I would expect an increased vacuum reading (unless the relief valve opens well within the green?) with a reduced airflow. What is typically seen ?