Samuel,
Any time the pitot and/or static system is opened, it must be checked for leakage.
The guidance for this check in in FAR 25.1325:
Any time either the pitot system or the static system is opened, and it would have to be opened to the install the AV-30, the system must be checked to determine if it’s still within tolerances. The FARs that apply are appendix E of Part 43.
The following is intact from the appendix:
(a) Static pressure system:
(1) Ensure freedom from entrapped moisture and restrictions.
(2) Perform a proof test to demonstrate the integrity of the static pressure system in a manner acceptable to the Administrator. For airplanes certificated under part 25 of this chapter, determine that leakage is within the tolerances established by §25.1325.
(3) Determine that the static port heater, if installed, is operative.
FAR 25.1325 describes how to do the test and what tolerances are permitted:
It is airtight except for the port into the atmosphere. A proof test must be conducted to demonstrate the integrity of the static pressure system in the following manner:
(i) Unpressurized airplanes. Evacuate the static pressure system to a pressure differential of approximately 1 inch of mercury or to a reading on the altimeter, 1,000 feet above the airplane elevation at the time of the test. Without additional pumping for a period of 1 minute, the loss of indicated altitude must not exceed 100 feet on the altimeter
e) Each system must be designed and installed so that the error in indicated pressure altitude, at sea level, with a standard atmosphere, excluding instrument calibration error, does not result in an error of more than ±30 feet per 100 knots speed for the appropriate configuration in the speed range between 1.23 VSRO with flaps extended and 1.7 VSR1 , with flaps retracted. However, the error need not be less than ±30 feet.
