Peter wrote:
rapid pressure change test
Never seen that either, but nice precaution to disconnect the VSI before doing that.
Peter wrote:
Interesting paragraph in AC43-6D:Static System and Pitot System. Damage can occur to instruments that are connected to
both the static system and pitot system when only the static system is evacuated. These
instruments may exceed the maximum design differential pressure. One method to
prevent this type of damage is to tie both the pitot and static systems together when
conducting static system checks. This should result in zero differential pressure
regardless of the degree of static system evacuation. Note that a leak in either system will
affect the test process.
This was the usual way to test the static system before the advent of automatic test sets. We still have an old manual test rig affectionately known as “coffee grinder” – a cubic box with a hand crank on top. The crank drives a leadscrew, which moves a piston in a cylinder.
I asked one of the top US instrument shops and this was the reply:
