Abstract: An adapter to test the static vent of aircraft instrumentation is provided. The test adapter comprises an adapter assembly and a seal holder. The adapter assembly comprises a plurality of prongs adapted to be inserted in the vent's holes. The assembly further comprises a locking mechanism cooperating with the prongs to secure the adapter assembly in place. A seal holder, adapted to be mounted on and over the adapter assembly comprises a seal and a hose connector to connect the adapter to the gas or pressure source. The adapter can also be provided with a blanking port which acts as a pre-test device and also as a storage unit for protecting the adapter assembly when not in use.